Central Cross Island Road Upgrading Project: Design

DESIGN COMPLETION REPORT

Central Cross Island Road Upgrading Project (CCIRUP) – Design & Documentation Completion Services Contract dated 17 December 2018 Prepared for the Land Transport Authority 6 December 2019

PROJECT REFERENCE NO. 5040021

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DESIGN COMPLETION REPORT Central Cross Island Road Upgrading Project (CCIRUP) – Design & Documentation Completion Services Prepared for Land Transport Authority

SMEC Internal Ref. 5040021 6 December 2019

Table of Contents 1 INTRODUCTION ........................................................................................................................................................ 1

1.1 Report Purpose ............................................................................................................................................. 1 1.2 Report Structure & Content .......................................................................................................................... 1 1.3 TOR Deliverable Summary ............................................................................................................................ 2

2 DESIGN STANDARDS ................................................................................................................................................ 4

3 KEY DESIGN CONSTRAINTS ....................................................................................................................................... 5 3.1 Overview ....................................................................................................................................................... 5 3.2 Minimisation of Resettlement Impacts ........................................................................................................ 5 3.3 LTA Completed Road Sections ..................................................................................................................... 5 3.4 Design & Civil Works Packages ..................................................................................................................... 6 3.5 Summary Packages and Road Sections ......................................................................................................... 6

4 DESIGN CRITERIA ...................................................................................................................................................... 7

5 ROAD UPGRADE DESIGN FEATURES......................................................................................................................... 9 5.1 Typical Cross Sections ................................................................................................................................... 9 5.2 Road Pavement Design ............................................................................................................................... 10 5.3 Alignment Options ...................................................................................................................................... 11 5.4 Slow Vehicle Bays ....................................................................................................................................... 11

6 POSTED AND DESIGN SPEEDS ................................................................................................................................ 14 6.1 Posted Speed .............................................................................................................................................. 14 6.2 Design Speed Regime.................................................................................................................................. 15

7 ROAD SAFETY ......................................................................................................................................................... 17 7.1 Overview ..................................................................................................................................................... 17 7.2 Road Safety Report by iRAP Introduction ................................................................................................... 17 7.3 Vehicle Occupant ........................................................................................................................................ 18 7.3.1 Countermeasures .............................................................................................................................. 18 7.3.2 Roadside Hazards .............................................................................................................................. 18 7.3.3 Curve Delineation .............................................................................................................................. 20 7.3.4 Street Lighting ................................................................................................................................... 20 7.3.5 Wide Centreline ................................................................................................................................. 21 7.4 Pedestrian ................................................................................................................................................... 22 7.4.1 Countermeasures .............................................................................................................................. 22 7.4.2 New Footpaths .................................................................................................................................. 23 7.4.3 Pedestrian Fencing ............................................................................................................................ 25 7.4.4 Unsignalised Crossing ........................................................................................................................ 26 7.5 Guardrails.................................................................................................................................................... 27

8 DRAINAGE DESIGN ................................................................................................................................................. 28 8.1 Overview ..................................................................................................................................................... 28 8.2 Climate Change Adaptation Measures ....................................................................................................... 28 8.2.1 Risk Assessment ................................................................................................................................ 28 8.2.2 Current ERAP Design Inclusions ........................................................................................................ 28 8.2.3 Conclusion ......................................................................................................................................... 30 8.3 Detailed Drainage Design Update ............................................................................................................... 30

9 PAVEMENT DESIGN ................................................................................................................................................ 31

10 ALTERNATIVE MATERIAL TYPES ............................................................................................................................. 33 10.1 Overview ..................................................................................................................................................... 33 10.2 Nickel Slag – Le SlandTM ............................................................................................................................. 33 10.3 Waste Rubber & Plastic .............................................................................................................................. 33 10.4 Cement Stabilisation ................................................................................................................................... 35 10.5 Coldmix asphalt – CarboncorTM .................................................................................................................. 36

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10.6 Conclusion................................................................................................................................................... 38

11 INTEGRATION OF SOCIAL-RELATED ELEMENTS ..................................................................................................... 40 11.1 Background ................................................................................................................................................. 40 11.2 Dedicated bus bays ..................................................................................................................................... 40 11.3 Bus Bay Shelters .......................................................................................................................................... 41 11.4 Street Lighting ............................................................................................................................................. 42 11.5 Dedicated Footpaths ................................................................................................................................... 43 11.6 Speed Humps .............................................................................................................................................. 44 11.7 Myna’s Supermarket realignment .............................................................................................................. 44 11.8 Papapapaitai Falls Carpark .......................................................................................................................... 45

12 CONCLUSION .......................................................................................................................................................... 46

13 PENDING ITEMS ..................................................................................................................................................... 48

14 APPENDIX 1: DESIGN CERTIFICATES ....................................................................................................................... 51

15 APPENDIX 2: REALIGNMENT OPTIONS ................................................................................................................... 53 15.1 KM 5+450 .................................................................................................................................................... 54 15.2 KM 6+000 .................................................................................................................................................... 56 15.3 KM 6+700 .................................................................................................................................................... 58 15.4 KM 14+900 .................................................................................................................................................. 60 15.5 KM 15+300 .................................................................................................................................................. 62

16 APPENDIX 3: SLOW VEHICLE BAY (SVB) ASSESSMENT ........................................................................................... 64 16.1 Index Plan ................................................................................................................................................... 64 16.2 SVB No. 1: KM 5+490 to KM 5+865............................................................................................................. 65 16.3 SVB No. 2: KM 6+155 to KM 6+500............................................................................................................. 66 16.4 SVB No. 3: KM 7+600 to KM 7+930............................................................................................................. 68 16.5 SVB No. 4: KM 8+900 to KM 9+185............................................................................................................. 69 16.6 Conclusion................................................................................................................................................... 70

17 APPENDIX 4: ROAD SAFETY STRIP PLAN ENGINEERING ASSESSMENT ................................................................... 71

18 APPENDIX 5: PAVEMENT DESIGN REVIEW – TRL OVERSEA ROAD NOTE 31 VS AUSTROADS ................................ 75 18.1 Purpose ....................................................................................................................................................... 75 18.2 Long-term behavior of subgrade CBR ......................................................................................................... 75 18.3 Pavement design validation from another acceptable method ................................................................. 75 18.3.1 Section 8. Design of Flexible Pavements – FLOW CHART .................................................................. 76 18.3.2 Section 5. Assessment of Design Subgrade CBR ................................................................................ 77 18.3.3 Section 7. Prediction of Design Traffic............................................................................................... 77 18.3.4 Section 8.3.1 Determination of Basic Pavement Thickness............................................................... 77 18.3.5 Section 8.3.2 Pavement Composition ............................................................................................... 79 18.3.6 Conclusion ......................................................................................................................................... 79 18.4 How TRL pavement design responds to increased rainfall ......................................................................... 79 18.5 Has CBR 8% been confirmed, will it change, and what is the risk to cut-and-fill slopes? ........................... 80

19 APPENDIX 6: PAVEMENT DESIGN REVIEW – UPDATE FOR NEW TRAFFIC COUNT DATA & FORECASTING ............ 81 19.1 Purpose ....................................................................................................................................................... 81 19.2 Background ................................................................................................................................................. 81 19.3 New pavement design (RN31 2019) ........................................................................................................... 81 19.3.1 Traffic assessment sections ............................................................................................................... 81 19.3.2 ADT & % HCV per section .................................................................................................................. 82 19.3.3 New growth rates .............................................................................................................................. 82 19.3.4 New analysis period .......................................................................................................................... 82 19.3.5 New results ........................................................................................................................................ 82 19.4 New Austroads comparison ........................................................................................................................ 83 19.5 Conclusion................................................................................................................................................... 84

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List of Figures Figure 1: No Overtaking Double Lines, LTA Samoa National Road Code, 2010 ............................................................................. 4

Figure 2: Example LTA Completed Road Section ............................................................................................................................ 5

Figure 3: Typical Section Option 1 – Selected for urban area ...................................................................................................... 10

Figure 4: Typical Section Option 6 – Selected for rural area ........................................................................................................ 10

Figure 5: Right Turn Bay ............................................................................................................................................................... 11

Figure 6: Slow Vehicle Bay, KM 7+635 to KM 7+915 .................................................................................................................... 13

Figure 7: iRAP Star Rating Comparisons ....................................................................................................................................... 17

Figure 8: Roadside Hazard Zone 0 to 5m...................................................................................................................................... 19

Figure 9: Improve Curve Delineation Example (KM 6+000) ......................................................................................................... 20

Figure 10: Final Design reflected Street Lighting (KM 4+420) ...................................................................................................... 20

Figure 11: Example Wide Centrelines, New Zealand Transport Agency, February 2012 ............................................................. 21

Figure 12: 1.0m Wide Centreline Planned for Final Design .......................................................................................................... 22

Figure 13: Example Flush Median Strip, New Zealand Road Code, 2015 ..................................................................................... 22

Figure 14: Final Design Footpath (KM 3+604 to KM3+700) ......................................................................................................... 23

Figure 15: iRAP Identified Potential New Footpath – Plan View (KM 4+420 to KM 6+900)......................................................... 24

Figure 16: iRAP Identified Potential New Footpath – Cross Section (KM 4+420 to KM 6+900) ................................................... 25

Figure 17: Example Pedestrian Fence .......................................................................................................................................... 26

Figure 18: Example Pedestrian Fence Application to Crossing (KM 0+119) ................................................................................. 26

Figure 19: Typical Rock Weir and Drop Structure Details ............................................................................................................ 30

Figure 20: Transport of Le SlandTM Nickel Slag, New Caledonia to Vanuatu, May 2018 ............................................................ 33

Figure 21: Cement-stabilised Road Shoulder ............................................................................................................................... 36

Figure 22: Carboncor Laboratory Test Result, September 2018 .................................................................................................. 37

Figure 23: Bus Stops, KM 18+130, Siumu ..................................................................................................................................... 41

Figure 24: Sample Road Lighting Position (left or east side) ........................................................................................................ 42

Figure 25: Example Solar-Powered Light Pole .............................................................................................................................. 42

Figure 26: New Siumu Footpath – Plan View (KM 18+110 to KM 19+640) .................................................................................. 43

Figure 27: Example Slurry Seal Application .................................................................................................................................. 43

Figure 28: New Siumu Footpath – Details (KM 18+110 to KM 19+640) ....................................................................................... 43

Figure 29: Existing Speed Hump (US Embassy) ............................................................................................................................ 44

Figure 30: Myna's Realignment – Newly Erected Building Structure ........................................................................................... 44

Figure 31: Myna's Realignment – Horizontal Shift ....................................................................................................................... 44

Figure 32: Myna's Realignment – Final Layout and Resettlement Impacts ................................................................................. 45

Figure 33: Papapapaitai Falls Viewing Carpark (KM 12+100) ....................................................................................................... 45

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List of Tables Table 1: Deliverables Summary (TOR) ............................................................................................................................................ 2

Table 2: CCIR Packages & Road Sections ........................................................................................................................................ 6

Table 3: Design Criteria .................................................................................................................................................................. 7

Table 4: ROW typical cross section options ................................................................................................................................... 9

Table 5. Slow Vehicle Bays (SVBs) ................................................................................................................................................ 12

Table 6: Posted Speed Limits, LTA Samoa National Road Code, 2010 ......................................................................................... 14

Table 7: Design Speed Regime, ERAP, 2016 ................................................................................................................................. 15

Table 8: Design Speed Regime Review/Changes, LTA-GCF, 2019 ................................................................................................ 16

Table 9: Final Design Speed Regime, LTA-GCF, 2019 ................................................................................................................... 16

Table 10: Pedestrian Crossing Schedule ....................................................................................................................................... 25

Table 11: Guardrails ..................................................................................................................................................................... 27

Table 12: Drainage Vulnerability to Climate Risk ......................................................................................................................... 28

Table 13: ERAP Pavement Design Typical Sections ...................................................................................................................... 31

Table 14: Final Pavement Design Regime .................................................................................................................................... 32

Table 15: Bus Bays Locations ........................................................................................................................................................ 40

Table 16: Task Checklist ............................................................................................................................................................... 46

Table 17: Pending Items ............................................................................................................................................................... 48

Table 18: Appendix 4 – Road Safety Strip Plan Engineering Assessment ..................................................................................... 72

Introduction

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1 Introduction 1.1 Report Purpose The purpose of this report is to document the outcomes of updating the detailed design documents, as per Chapter 4.2.3 of the Terms of Reference (TOR). This is also TASK 4 Update Detailed Design of the Inception Report (January 2019).

It is issued as original draft of the FINAL Design Completion Report (FINAL-DRAFT00/deliverable D12), following submission of the DRAFT Design Completion Report (DRAFT00/deliverable D5) on 01-Jul-19, receipt of LTA review comments on 29-Jul-19, and reissuance of the DRAFT Design Completion Report (DRAFT01) on 31-Jul-19. This document is an update of the latter, along with separately provided Drainage Design Report.

1.2 Report Structure & Content This report is structured to cover the following topics:

• Design standards • Key design constraints • Design criteria • Road upgrade design options • Posted and design speeds • Road safety • Drainage design • Pavement design • Alternative material types • Integration of social-related elements

Collectively, they explain the background behind the design. These topics are followed by a conclusion chapter (Chapter 12). It includes a tabulated checklist of design and/or drafting tasks identified during the ADB-TA1, as documented in the CCIR Engineering Review Report, June 2019, and as appropriately modified to suit this report and final project context. The up-to-date final status of each task checklist line-item is reported on.

This chapter is followed by another entitled Pending Items (Chapter 13). Its purpose was to isolate out tasks that were, at time of DRAFT report submission (31-Jul-19), remaining to complete. This included tasks that were the sole responsibility of SMEC to complete, or tasks/matters that required feedback or action from the LTA. Utility relocation matters were covered in a separate report2, but are also briefly commented on in this chapter.

In order to maintain focus on design relevant topics, this report may mention but typically excludes commentary on:

• Technical specifications • Bill of Quantities (BOQ) • Engineer’s estimates • Bidding documents

These are all separate deliverables of the TOR, and have all been completed to draft final status (subject only to final client review, and if required, any agreed resultant changes). Design-relevant Schedules, and Drawings do however form part of the bidding documents. Draft final versions of these are provided separately along with all bidding document. Refer further to Chapter 1.3.

Design Certificates are provided in Appendix 1. They will be finalised and submitted following peer review of all completed design tasks and drawings (completed), and final review feedback of the client (pending).

1 Asian Development Bank (ADB) Technical Assistance (TA) Consultancy, delivered by SMEC from Aug-18 to Jun-19.

2 Utility Relocation Report, SMEC. 18-Sep-19.

Introduction

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1.3 TOR Deliverable Summary Table 1 includes verbatim TOR deliverables under “No.” and “Description”, submission dates, and remarks/explanations to each. Along with submission of this report, all deliverables required of the contract including terms of reference (TOR) are now submitted as DRAFT FINAL status for the final review of the LTA, including project funders UNDP-GCF and ADB. Following receipt of review comments and agreement to changes, relevant documents will then be resubmitted as FINAL status.

Table 1: Deliverables Summary (TOR)

NO. DESCRIPTION DATE REMARK

D0 Inception Report 21-Jan-19 25-Mar-19

Draft and final reports

D1, D2, D3

Survey Stage 1 Completion Report, including copy of DRAFT Surveying Processing Manual with checklists, and FINAL corrected cadastral model in drawing format.

22-Feb-19 09-Apr-19 25-Apr-19

22-Feb: Report with all as mentioned except the full manual (checklist only instead). 09-Apr: updated report 25-Apr: final report

D4 Utility Relocation Report 18-Sep-19 Three (3) months from commencement of the assignment

D5 DRAFT Design Completion Report, including summary of design, any outstanding issues and concerns, supporting documents including calculations, and DED & ROW Drawings (Packages 1 & 2)1 in PDF format.

15-May-19 01-Jul-19 31-Jul-19

15-May: ROW drawings (see further below) 01-Jul: DCR + DP2 drawings. 31-Jul: updated DCR following LTA meeting to discuss key outstanding issues, agree on changes, and provide review comments.

D6 FINAL Resettlement Plan (REV01), including site verified final Inventory of Losses Table/s.

15-May-19 02-Sep-19 10-Oct-19 22-Oct-19

15-May: IOL table 02-Sep: RP report + updated ROW drawings + updated IOL table 10-Oct: updated ROW drawings 22-Oct: updated IOL table

D7, D8

FINAL Design Drawings (IFC Drawings2) and FINAL BOQs for each CW Package, following LTA review and updates from D5.

06-Dec-19 As submitted same time as this report. Drawings are issued as detailed design status for final review and comment, as noted by UNDP-GCF. Issue For Construction (IFC) status drawings will be issued following the review and final revision process. Drawings are provided as 3 sets:

1. Design Package 1 (DP1): KM 0+000 to KM 3+127 2. Design Package 2 (DP2): KM 3+127 to KM 19+686 3. DP2-CW2 (civil works package 2): KM 15+500 to KM

19+686. DP1 & DP2 are relevant to civil works package 1 (CW1); up to KM 15+500 for DP2. DP2-CW2 includes all relevant generic drawings from DP2, and omits those are not specific to it (that only apply to CW1). Although DP2 will include some sheets that are not specific to CW1, the whole set will be issued so that there is always a complete version beyond this design phase of the project. This drawing arrangement is clarified in the bidding documents (Section 6 ERQ). BOQs are provided for CW1 & CW respectively. They are printed to PDF from the combined BOQ-Estimate MS Excel file.

D9 Full Bidding Document sets, including consolidation and minor updates of standard documents and forms from ADB-TA, supplementary information,

15-Oct-19 06-Dec-19

15-Oct: Draft final documents for CW2 were submitted at this time, but are now also submitted as of 06-Dec. Includes some minor updates, but consider that 06-Dec version now fully supersedes 15-Oct-19 submission.

Introduction

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NO. DESCRIPTION DATE REMARK and final technical specifications (drawings and BOQ separate, as per D7).

06-Dec: As submitted same time as this report. ADB format Standard – or commercial – bidding documents (SBDs) are provided as separated out for both CW1 and CW2. The latest versions with SMEC are provided, although some of these may have been updated/superseded by the LTA/ADB since previous submission of the same to both LTA & ADB on 17 & 19-Jun-19. New updates from SMEC include IFB, Section 4 BDF, and Section ERQ. Supplementary information includes several documents but most of these have been with the LTA/ADB for some time now. Aside from resending the Project Overview document previously submitted 14-Oct-19, SMEC has not for the remainder resubmitted latest versions in as doing so would likely create document control confusion. Tech specs for both CW1 & CW2 are provided in full, as 2 separate sets. Of the total 34 tech spec parts (separate MS Word documents), like-for-like parts of CW1 & CW2 are identical, with application to one or the other being clarified within the document, as applicable. All bidding documents are provided in separate CW1 & CW2 folders, irrespective of any content duplication. A separate Bidding Document Checklist is also provided, along with further comments. This is provided as a communication and coordination tool only (it does not form part of the bidding documents). Refer to this for further details.

D10 FINAL confidential Engineer’s Estimate, for each CW package, and for all CW packages combined.

31-Jul-19 04-Nov-19 06-Dec-19

The Engineer’s Estimate is provided in the BOQ-Estimate MS Excel file. In reflects CW1, CW2-A & CW2-B and total project values broken down into a Summary, 7 separate Bill items, Dayworks, and a Summary Provisional Sum table, as reflective of the BOQ breakdown. 31-Jul: original draft combined BOQ-Estimate submitted to LTA, followed only be the preliminary design stage estimate submitted by SMEC to LTA Sep-16. 04-Nov: updated estimate for CW2 (CW1 still needed to be completed). 06-Dec: final draft for both CW1 & CW2/total project, including minor updates to CW2.

D11 FINAL Design Completion Report 06-Dec-19 This report, and separate Drainage Design Report. As requested by UNDP-GCF, SMEC is additionally submitting drainage flow calculations for purposes of others (separate project) assessing stormwater runoff volumes to the Vaisigano River catchment area. These calculations are however provided for the entire CCIR.

D12 Survey Stage 2 Completion Report, including copy of FINAL Surveying Processing Manual with checklists (individual lot subdivision plans will be formally registered separately with the MNRE).

06-Dec-19 As submitted same time as this report. Includes 2 separate documents:

1. Survey Stage 2 Report 2. Samoan Road Survey Manual, Edition 1

D13 Technical procurement support documents including clarifications, addenda, and other relevant documents.

N/A No longer relevant.

Design Standards

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2 Design Standards The following documents were used for design purposes:

• Geometric Design: − Austroads Guide to Road Design, Part 3: Geometric Design, 2017 − Austroads Guide to Road Design, Part 4: Intersections and Crossings, 2017

• Pavement Design: − Transport Research Laboratory Overseas Road Note 31, A guide to the structural design of bitumen-surfaced roads

in tropical and sub-tropical countries (TRL ORN 31), 4th Edition, 1993 − Austroads Guide to Pavement Technology, Part 2: Pavement Structural Design, 2017

• Design of steep grades: AASHTO 2004, Part 2 • Drainage Design: Austroads Guide to Road Design, Part 5: Drainage, 2013 • Pavement Marking and Road Signs:

− New Zealand Manual of Traffic Signs and Markings (MOTSAM), Part 1 and Part 2, 2010 − LTA Samoa National Road Code, 2010

For the latter, the Samoan road code was referred to because of some unique to Samoa factors that included:

• Posted speed limits being stated and enforced in miles per hour (mph), as well as kilometres per hour (kph).

• Field observations from Samoa that solid white no overtaking lines (NOLs) are used instead of solid yellow, the latter of which is specified by MOTSAM. Whilst it was initially proposed to adopt the double white lines for no overtaking in both directions, as reflected in the code (Figure 1), upon further review and assessment, the designer has opted to adopt the MOTSAM instead. This is primarily because the road code only implies white lines by way of the image i.e. it is not a clear requirement. Furthermore, the design application of NOLs according to MOTSAM is not always for double lines, but in many instances, for one travel direction only. Additionally, advanced warning lines (AWLs - in advance of NOLs) and differing colour RRPMs are also applicable when following MOTSAM, the combination of which should, as a matter of best practise and in the interest of increased safety, only be applied when following MOTSAM in its entirety for such line markings. Yellow AWLs and NOLs have therefore been adopted and reflected in final drawings and bidding documents.

Figure 1: No Overtaking Double Lines, LTA Samoa National Road Code, 2010

Key Design Constraints

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3 Key Design Constraints 3.1 Overview In understanding the design intent of this road upgrade project – the Central Cross Island Road Upgrading Project (CCIRUP) – it is firstly important to understand some key constraints. These have fundamentally included the following primary objectives:

• Minimisation of resettlement impacts • No major civil works (and thus road design) for the previously upgraded road sections performed by the LTA in 2013.

Although not a design constraint, it is also important to note that there are 2 sets of design drawings that differ from the intended civil works construction packages.

These matters are further explained in the following sub-chapters.

3.2 Minimisation of Resettlement Impacts Under ERAP a target nominal road ROW width of 16.0m was approved to be pursued by the LTA from the project start point (KM 0+000) up to KM 11+014. From this point to the project end point (KM 19+686), a nominal 22.0m wide ROW width was approved, being a less physically constrained and predominately ‘borderless’ existing road corridor than for up to KM 11+014. 22.0m is consistent with Clause 41. Road Reserves of the Land Transport Authority Act 2007.

Subsequent discussions involving the project funder ADB however resolved to revise the 22.0m wide ROW down to 16.0m. This was approved by the LTA, and is a change that has now been generally reflected in the updated drawings. The ROW width is however for practical reasons wider than this in many locations. These reasons generally include: 1) logical tie-in to existing cadastral boundaries and non-land assets such as fence lines, 2) to provide sufficient width for road side drains and outer lying relocated utilities to be located, and 3) for road curves that require a wider footprint. In some instances, current CCIR ROW land areas have been identified for possible ‘return’ to adjacent private property land owners. Such details were captured in the ROW Drawings issued to the LTA on 15-May-19. The ROW Drawings were later reissued on 02-Sep-19 (REV01), 10-Oct-19 (REV02), and 4 sheets of the entire set on 22-Oct-19 (REV03). The revisions were made to capture updates to drainage outfall easements, and to capture the corrected impact on adjacent properties due to the localised realignment (Chapter 3.5).

3.3 LTA Completed Road Sections Following Tropical Cyclone Evan (TCE) in December 2012, about 4 km of heavily damaged road sections were repaired and improved by the LTA under emergency works. An example image of one of these road sections in provided in Figure 2. In order to preserve this asset investment of the LTA, these road sections were confirmed by the LTA to be excluded from this project’s major civil works scope i.e. full-width upgrading, including utility relocation. Rather, treatment objectives within these road sections were to include ‘surface’ road safety improvements only i.e. road edge maker posts, reflective raised pavement makers (RRPMs), and line marking. This has been reflected in the final drawings and bidding documents.

The LTA also confirmed that a new ROW corridor should be established for these road sections, as for the remainder of the alignment. Thus, the intent was to establish a completely new ROW corridor for the entire project road length. This new corridor is reflected in the ROW Drawings, and is likewise represented on many drawing series of the civil works drawings. The existing features series (EF Series) in particular refers, which for any given road section reflects the new ROW corridor in the top view port (proposed), and incumbent corridor in the bottom view port (existing).

Figure 2: Example LTA Completed Road Section

Key Design Constraints

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3.4 Design & Civil Works Packages The original World Bank funded stage of the project – the Enhanced Road Access Program (ERAP) – included civil works (CW) procurement targeted towards bidding two construction packages, with priority being to upgrade the 1st road section from project start point to the boundary of the 1st previously upgraded LTA road section. As a result, ERAP CW Package 1 was intended to be an urban design from KM 0+000 to KM 3+127, and CW Package 2 combined urban and rural from KM 3+127 to the end point at KM 19+686. In order to avoid major design and drafting rework and associated delays, maintaining reflection of these 2 distinct packages has been carried over to this, the second or ADB/GCF3 funded stage of the project. In order to avoid confusion with now newly intended civil works packages, these two distinct drawing sets are referred to as Design Package 1 - Drawings (DP-1) and Design Package 2 – Drawings (DP-2).

The new CW packages include CW-1 for international advertisement and CW-2 for national advertisement. CW-1 includes two “sections” and CW-2 includes two “lots”. The difference in terminology is because CW-1 will be tendered and contracted as one construction contract, while CW-2 will be tendered as two separate construction contracts, with the option for bidders to tender on either one or both together if they can prove compliance with eligibility criteria for implementing both.

3.5 Summary Packages and Road Sections A summary of the entire project alignment that reflects the various different road sections and packages is provided in Table 2.

Table 2: CCIR Packages & Road Sections

ITEM FROM (STA.) TO (STA.) SECTION LENGTH (KM) PROJECT TOTAL 0.000 19.686 19.686

DESIGN PACKAGE 1 0.000 3.127 3.127 DESIGN PACKAGE 2 3.127 19.686 16.559a

URBAN AREA 0.000 4.420 4.420 RURAL AREA 4.420 19.686 15.266a

COMPLETED SECTION A 3.127 3.604 0.477 TO CONSTRUCT (URBAN) SECTION 2.1 3.604 4.420 0.816 TO CONSTRUCT (RURAL) SECTION 2.2 4.420 6.512 2.092

COMPLETED SECTION B 6.512 6.997 0.485 TO CONSTRUCT (RURAL) SECTION 2.3 6.997 10.612 3.615a

COMPLETED SECTION C 10.612 11.014 0.402 TO CONSTRUCT (RURAL) SECTION 2.4 11.014 11.764 0.750

COMPLETED SECTION D 11.764 13.089 1.325 TO CONSTRUCT (RURAL) SECTION 2.5 13.089 13.239 0.150

COMPLETED SECTION E 13.239 14.220 0.981 TO CONSTRUCT (RURAL) SECTION 2.6 14.220 19.686 5.466

CONSTRUCTION PACKAGE CW-1 SECTION 1 0.000 4.420 4.420 CONSTRUCTION PACKAGE CW-1 SECTION 2 4.420 15.500 11.080

CONSTRUCTION PACKAGE CW-2 LOT 1 15.500 17.500 2.000 CONSTRUCTION PACKAGE CW-2 LOT 2 17.500 19.686 2.186

Note: a Additional 8.0m due to realignment from KM 7+312 to 7+968.5 (revised to KM 7+976.5). This realignment was required to an error found with the original topographic survey. It has since been corrected, and reflected as such in final drawings.

3 GCF – Green Climate Fund, administered by the United Nations Development Programme (UNDP).

Design Criteria

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4 Design Criteria Adopted road design criteria is reflected in Table 3. A 20-year design life was specified in the TOR and has been complied with, as-is typical for such road upgrade projects.

Table 3: Design Criteria

CRITERIA REMARK Urban (4.420 Km)

Design Speed / Posted Speed

40 kph / 40 kph (25 mph)

Austroads recommends adopting a design speed 10 kph higher than the posted speed for safer road geometry, but because of a highly constrained existing ROW, matching rather than exceeding has been adopted. mph (miles per hour) is the legal speed limit in Samoa, also expressed in kph (kilometres per hour).

Carriageway width 7 m

Lane widths 3.5 m 2-lane (1-lane in each direction)

Shoulders (both sides) Nominal 4.5 m wide (varies) including: - 1.5 m wide grassed drainage corridor (2 % crossfall) - 1.5 m wide concrete footpath (1 % crossfall) - 1.5 m wide grassed utility corridor (varies +/- to max. 1H:1V)

For grassed utility corridor see batter slopes comment below. H – horizontal V – vertical

Crossfall 3 % Superelevation 3 % maximum Was previously 5% under ERAP; now improved to

3% Grades Kerbed: 1 % desirable / 0.3 %

minimum / existing maximum The CCIR is an inherently steep road. Design intent has been to adopt no more than max. existing longitudinal grades in order to minimise adverse impacts on land acquisition.

Batter slopes (earth) Cut: 1:1 maximum Fill: 1:1 maximum

Slope varies from nearest rigid structure e.g. concrete footpath/kerb line to limit of works (LOW) line up to maximum stated slope.

Stopping Sight Distance 34 – 40 m Min. Crest Curve K Value under ERAP was range 2.5 – 3.5; now improved to 3.6 Reaction Time under ERAP was 1.5 (s)econds; now improved to 2.0 s

Min. Horizontal Curve

45 m Min. Crest Curve Length 20 – 30 m

Min. Crest Curve K Value 3.6

Reaction Time 2.0 s Coefficient of Deceleration 0.36

Rural (15.266 Km) Design Speed /

Posted Speed 60 kph maximum / 56 kph (35 mph)

Same comment as above re Austroads. Refer to Chapter 6 for further details.

Carriageway width 7 m Lane widths 3.5 m 2-lane (1-lane in each direction)

Shoulders (both sides) 2 m unsealed/cement stabilised (4 % crossfall)

Crossfall 3 %

Superelevation 7 % maximum Was previously 10% under ERAP; now improved to 7%

Design Criteria

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CRITERIA REMARK Grades Kerbed: 1 % desirable / 0.3 %

minimum / existing maximum Unkerbed: 1 % desirable / 0.5 % minimum / existing maximum

Same remark as for urban above.

Batter slopes (earth) Cut: 1:1 typical/maximum Fill: 1:1 typical/maximum

1:1 adopted based on site observations of similar/steeper stable slopes throughout the entire project alignment and in order to minimise land acquisition and resettlement impacts

Stopping Sight Distance 40 – 73 m Min. Horizontal Curve Length under ERAP was 100 m; now reduced to 75 m (still acceptable)

Min. Horizontal Curve Length

75 m Min. Crest Curve Length 40-50 m

Min. Crest Curve K Value 9.3 – 11.8 Reaction Time 1.5 s

Coefficient of Deceleration 0.36 Side Roads

Carriageway width Match existing to nearest 0.5m

Was to match to nearest 1.0m. All existing side roads vary in width. General approach has been to establish new side road tie-in to a uniform width similar/slightly wider than existing surveyed width of road

Shoulders (both sides) Urban: Kerbed Rural: 0.5 m unsealed (unstabilised)

Unsealed shoulders are a continuation of the basecourse layer outwards, hence no shoulder cement stabilisation applicable, or necessary.

Crossfall Varies Was 3% Superelevation Not applicable Was 5% maximum

Grades 0.3 % minimum / existing

Verges 0.5 m wide minimum

(2 % crossfall)

Batter slopes (earth) Cut: 1:1 typical/maximum Fill: 1:1 typical/maximum Fill:

Same remark as for rural above.

Road Upgrade Design Features

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5 Road Upgrade Design Features 5.1 Typical Cross Sections During the preliminary design stage under ERAP a total of 6 different typical full-width cross sections were considered for the road upgrade. These primarily considered varying width shoulders and drainage arrangements for both urban and rural areas of the CCIR. Alternate ROW widths were also considered for the rural area. A summary of each cross section considered is provided in Table 4.

Table 4: ROW typical cross section options

OPTION NO.

CCIR ROAD SECTION

KM4 (TO /

FROM)

ROW WIDTH

(M) DESCRIPTION

1

PACKAGE 1 & 2 URBAN

0+000 to

4+600

16.0

Kerbed 7.0 m wide carriageway (no shoulders) with std 4.5 m wide verge both sides that includes a 1.5 m wide piped drainage corridor LHS against kerb, 1.5 m wide footpath both sides, and 1.5 m wide utility in berm corridor against ROW boundary. Water utility proposed for RHS. Street lighting proposed for inside edge of footpath both sides.

2 16.0

Kerbed 8.2 m wide carriageway (including 0.6 m wide sealed shoulders both sides) with std 3.9 m wide verge both sides that includes a 0.90 m wide U-shaped RC lined (including cover slabs) drainage corridor against kerb, 1.5 m wide footpath both sides, and 1.5 m wide utility in berm corridor against ROW boundary. Water utility proposed for RHS. Street lighting proposed for outside edge of footpath both sides.

3 16.0

Unkerbed 11.0 m wide carriageway (including 2.0 m wide sealed shoulders both sides) with std 2.5 m wide verge each side that includes a 1.0 to 2.0 m wide* RC lined trapezoidal drainage corridor both sides, and a 0.5 to 1.5 m wide* shared utility in berm / footpath corridor both sides against ROW boundary. Water utility proposed for RHS. Street lighting proposed for outside edge of shoulders, although not ideal from a safety perspective. *Refer to the drawing note about variable drainage and shared utility in berm / footpath corridors.

4

PACKAGE 2 RURAL

4+600 to

19+673

16.0 (min.)

Unkerbed 10.0 m wide carriageway (including 1.5 m wide unsealed shoulders both sides) with std 3.0 m wide verge each side that includes a 1.0 to 2.5 m wide rip rap lined trapezoidal drainage corridor both sides, and a 0.5 to 2.0 m wide utility in berm corridor both sides against ROW boundary. Water utility and street lighting assumed not applicable.

5 16.0 (min.)

Unkerbed 10.0 m wide carriageway (including 1.5 m wide sealed shoulders both sides) with std 3.0 m wide verge each side that includes a 1.0 to 2.5 m wide RC lined trapezoidal drainage corridor both sides, and a 0.5 to 2.0 m wide utility in berm corridor both sides against ROW boundary. Water utility and street lighting assumed not applicable.

6 22.0 (max.)

Unkerbed 11.0 m wide carriageway (including 2.0 m wide unsealed shoulders both sides) with std 5.5 m wide verge each side that includes a 1.0 to 2.5 m wide rip rap lined trapezoidal drainage corridor both sides, and a 3.0 to 4.5 m wide utility in berm corridor both sides against ROW boundary. Water utility and street lighting assumed not applicable.

The LTA selected Option 1 for the urban area and Option 6 for the rural area. These are reflected in Figure 3 and Figure 4. As previously mentioned in Chapter 3.2, LTA confirmed that the previously planned nominal ROW width of 22.0m would be reduced to 16.0m. As such, Option 6 has been altered to suit, as now reflected in DP-2.

4 Previous ERAP project stage, now updated to KM 4+420 for urban/rural boundary and end point KM 19+686


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Figure 3: Typical Section Option 1 – Selected for urban area

Figure 4: Typical Section Option 6 – Selected for rural area

5.2 Road Pavement Design The road pavement design performed under ERAP was as per the TOR specified design standard Transport Research Laboratory (TRL) Overseas Road Note (ORN) 31: A guide to the Structural Design of Bitumen-surfaced Roads in Tropical and Sub-tropical Countries (TRL ORN 31). As pavement design inputs, it considered historical traffic count data provided by the LTA and inferred subgrade strength values (% CBR) based on field and laboratory studies performed by SMEC.

A parametric cost analysis of various pavement design profiles was also performed. This analysis considered urban and rural road sections separately, as well as a possible option of reusing existing road base material as a cost saving measure. Full details are documented in the ERAP Pavement Design Report, January 2017, but it ultimately concluded that there was no real benefit


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to project to reuse existing road base material in new subbase and base course pavement design layers. For further discussion on road pavement design refer to Chapter 9.

5.3 Alignment Options Being a road upgrade and due to highly limiting and complex constraints concerning land acquisition, alternative alignment options were not assessed under ERAP, either in a macro (entire alignment) or micro (per section of road or per curve) scale.

During the ADB fact-finding mission (FFM) in February 2019, a total of five conceptual realignment options were however presented to the LTA for consideration. These options are provided in Appendix 2, and were for the following locations:

• KM 5+450 • KM 6+000 • KM 6+700 • KM 14+900 • KM 15+300

Due mainly to additional land acquisition concerns, none of these were adopted, but a design modification for KM 5+450 was agreed to. This was to include a dedicated right turn bay for southbound CCIR traffic (from Apia) into the existing side road in this location. As such, the road design was widened in this location to accommodate it. The final right turn bay design is reflected in Figure 5.

5.4 Slow Vehicle Bays During the ADB FFM, the LTA CEO requested SMEC to look at incorporating passing lanes in the final design documents. As passing lanes are typically applied to high-speed road environments, SMEC focused on providing a more fit-for-purpose solution in the form of slow vehicle bays (SVBs). SVBs are commonplace in developed countries for low-speed environments, especially in winding, hilly terrain that is atypical to the CCIR, and for application to uphill directional traffic in typically steep terrain. This is because slow vehicles (typically heavy class vehicles or HCVs i.e. buses, trucks) take less time and require lower acceleration and overtaking speeds than for conventional use traffic (cars, motorbikes) to safely overtake on steeper grades.

New Zealand and Australia both comprehensively address SVBs in existing literature. From Australia, their design is well documented in Austroads, which New Zealand also adopt. New Zealand also specifically cover SVBs in MOTSAM, the adopted design standard for signs and lines (road marking).

Although SVBs are relatively short in length compared to passing lanes, identifying suitable locations along the CCIR for their inclusion was still highly constrained by topography, locations of side roads and private property access points, and would still need to achieve the overarching objective of minimising resettlement impacts. A further consideration was the likelihood of being effectively used and thus beneficial to road users. In this regard, it was determined that benefits for the south-side of the CCIR (from about KM10+000 onwards) would be largely ineffectual, for either direction of travel.

SMEC therefore proceeded with a rapid desktop analysis of the north-side CCIR (from Apia southwards). This study considered current road design alignment, topographical and cadastral survey features, anticipated traffic volumes, safety, and surrounding land use impacts based primarily off latest available satellite imagery. The result was identification of a total 4 feasible locations for SVBs, as follows:

• SVB No.1: KM 5+490 to KM 5+865 (375m length) • SVB No. 2: KM 6+155 to KM 6+500 (350m) • SVB No. 3: KM 7+600 to KM 7+930 (340m) • SVB No. 4: KM 8+900 to KM 9+185 (285m)

Their inter-relationship was also considered. For example, it was identified that SVB No. 1 & 2 would be too close in proximity to be effective overall (No. 1 would be used, but No. 2 too infrequently). In making this assessment it was determined that SVB No. 4 would experience low anticipated use because of low anticipated traffic volumes and already suitable sight lines/distances for safe overtaking in both directions.

The final recommendation and agreement by the LTA was to proceed with including SVBs No. 1 & 3. As a result, these are now fully integrated into the final road design.

Figure 5: Right Turn Bay


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A summary of each SVB as well as overall conclusion is provided in Table 5. A copy of adopted SVB No.3 from the SL Series (signs & lines) drawings showing associated road signs is provided in Figure 6. Further SVB details provided to the LTA are provided in Appendix 3.

Table 5. Slow Vehicle Bays (SVBs)

NO./LOCATION/DATA BENEFITS

SVB No.1: KM 5+510 to KM 5+840

Length = 330m Gradient = av. 9.0% (3 to 12%) Land use impacts: moderate Additional land acquisition: negligible Conclusion: Feasible, but not in isolation from SVB No. 2/ADOPTED

• Sharp curves @ end of SVB are more desirable/still acceptable from safety perspective than No. 2 (No. 2 unsafe due to sharp curve at KM 6+500).

• Closest to Apia (more beneficial to road users). • Steeper than No. 2, so better to have here. • No. 2 has 2 driveway entrances around KM6+500, hence undesirable/unsafe to

terminate here. • Skewed driveway near termination point at KM5+900 can be improved

(straightened) plus vegetation removed to improve sight distances. • Overall: safer than No. 2.

NOTE: Was assessed against No. 2 as they are in close proximity to each other.

SVB No. 2: KM 6+155 to KM 6+500

Length = 375m Gradient = av. 9.0% (3 to 12%) Land use impacts: moderate Additional land acquisition: negligible Conclusion: Feasible, but not in isolation from SVB No. 1

• Nil (compared to No. 1)

SVB No. 3: KM 7+635 to KM 7+915

Length = 280m Gradient = av. 7.0% (5 to 10.5%) Land use impacts: minimal Additional land acquisition: moderate Conclusion: Desirable/ADOPTED

• Desirable location • Less additional land to acquire than for No. 4

SVB No. 4: KM 8+900 to KM 9+185

Length = 285m Gradient = av. 3.5% Land use impacts: minimal Additional land acquisition: moderate Conclusion: See BENEFITS

• Desirable location BUT use is expected to be minimal given lower traffic volumes in this location, and that sight lines are already safe for overtaking in both directions, plus, it is near the road crest.


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Figure 6: Slow Vehicle Bay, KM 7+635 to KM 7+915

Posted and Design Speeds

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6 Posted and Design Speeds Austroads Guide to Road Design (AGRD)5 states that:

“the design speed is a speed fixed for the design and correlation to the geometric features of a carriageway that influence vehicle operation. It is selected during the design process and is related to either the intended operating speed or the posted speed limit of a road or section of road. Operating speed can be measured for an existing road. If the operating speed varies along the road, the design speed must vary accordingly. Identification of the operating speed is fundamental to the development of any roadway facility.”

Operating speeds were not specifically measured for this project, but in determining a suitable design speed regime, the posted speed combined with assumed operating speeds for topographically constrained road sections were taken into consideration i.e. those sections of road where operating speeds were either known or expected to be less than the posted speed.

The first consideration is posted speed, as explained in the following sub-chapter.

6.1 Posted Speed Posted speeds in Samoa are unique to Samoa in the sense that they are stated and enforced in both miles per hour (mph) and kilometres per hour (kph). Speed limits are sign posted throughout the islands, but are generally applied as reflected in the following Table 6.

Table 6: Posted Speed Limits, LTA Samoa National Road Code, 2010

For project design purposes:

• the 15 mph speed limit is not considered. • the 25 mph speed limit was agreed with LTA to be applied for the entire urban area, being beyond the mentioned 2-

mile boundary at the gates to the Robert Louis Stevenson (RLS) memorial. The RLS gates are about project chainage KM 1+720, whereas the newly defined urban/rural boundary is at KM 4+420. This means that a lower speed limit will now be enforceable for an additional 2.7 km length of the CCIR. This is seen as a positive road safety development, due to its urban setting and narrow corridor.

• Beyond KM 4+420: 35 mph.

In summary, a posted speed of 25 mph/40 kph has been adopted for the urban area and 35 mph/56 kph for the rural area. SMEC additionally updated/finalised LTA’s standard drawings for all speed limit signs, which can now be applied as the new standard throughout Samoa.

5 Austroads Guide to Road Design (AGRD), Part 3: Geometric Design, 2017, Chapter 2.2.5 Design Speed and Operating Speed.


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6.2 Design Speed Regime The design speed regime that was adopted under ERAP is provided in Table 7.

Table 7: Design Speed Regime, ERAP, 2016

STATION (FROM)

STATION (TO)

DESIGN SPEED (KPH)

0+000 4+606 40 4+606 5+218 60 5+218 5+486 50 5+486 5+843 60 5+843 5+933 50 5+933 6+163 40 6+163 6+551 50 6+551 6+682 40 6+682 7+107 60 7+107 8+062 50 8+062 11+853 60

11+853 11+975 50 11+975 13+629 60 13+629 14+176 40 14+176 15+017 50 15+017 19+686 60

As mentioned in the ERAP Preliminary Design Report, February 2017: “Adopting the abovementioned design speeds is a specific approach to the CCIR project, […] the purpose of it is to minimise land acquisition requirements.”

As a result, the reviewed design geometry was formulated on the basis of following the existing road centreline alignment with generally minor ‘tweaks’ made to ‘shape’ the road according to standardised curve radii, widening, transitions and superelevation. Given the generally steep, winding, and narrow topography of the existing road ROW, this was considered to be a generally acceptable approach, but in peer review performed under the ADB-TA (2018) it was further noted from Austroads that it is inappropriate to change the design speed for lengths as short as 500 m, of which there were found to be numerous such instances in the ERAP design. These short sections were flagged as being departures from the design standard. As such, their forward visibility and road safety were under the LTA-GCF6 (2019) assessed in further detail with a view towards a design speed regime change, and/or provision of specific additional signs. This assessment was made based on setting a moderated ‘desirable’ baseline of design speed 10 kph higher than the posted speed limit, with 10 kph higher being the generally recommended desirable outcome of Austroads. The ‘moderated’ baseline is because of 2 factors: 1) the important project objective of minimising resettlement impacts (road geometry suitable for higher design speeds requires additional road width), and 2) the fact that for the higher posted speed rural area, the mph speed limit converted to kph is 56 kph, being already 4 kph or 40% of the recommended desirable 10 kph higher from Austroads. The results of the peer review are summarised in Table 8 overleaf.

As can be seen from Table 8, a total of 3 design speed sections were changed as a result of the review. These were all increased by 10 kph, and have resulted in there now being a reduced total of 10 design speed zones (previously 16). Table 12 provides a final adopted summary of the design speed zones. As reflected, there are now 2 remaining zones with lengths of less than 500 m, but as noted from Table 8, these remain because they are within completed road sections i.e. they will not be upgraded/realigned as part of this project. In all instances, including these, sharp and very sharp curves were always planned under ERAP to have speed advisory warning signs installed, and have remained so.

As a final comment, no geometric realignment was required as a result of this review.

6 Land Transport Authority (LTA), Green Climate Fund (GCF) funded Consultancy, delivered by SMEC from Dec-18 to Dec-19.


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Table 8: Design Speed Regime Review/Changes, LTA-GCF, 2019

STATION (FROM)

STATION (TO)

LENGTH (M)

DESIGN SPEED (KPH) REMARK

ERAP LTA-GCF

0+000 4+606 4,606 40 no change

Matching 40 kph posted speed as opposed to exceeding by 10 kph (50 kph) considered appropriate for the entire urban area (up to KM 4+420) due to the highly-constrained width of existing ROW/objective of minimising resettlement impacts – OK

4+606 5+218 612 60 no change Exceeds 56 kph posted speed (same applies for other 60 kph zones) – OK

5+218 5+486 268 50 60 3 sharp curves. Now consistent speed zone so problem of < 500 m length has now been removed. 40 kph advisory speed signs (PW-25) were planned to be installed under ERAP, and still will be.

5+486 5+843 357 60 no change No longer issue of < 500 m length due to change made above.

5+843 5+933 90 50 no change Was very short in order to transition down from 60 to 40 kph leading up to very sharp curve (see next remark). Reduced design speed to remain as-is, but note the following changes.

5+933 6+163 230 40 50 1 very sharp curve (before Bahai Temple carpark entrance). Was 40 kph because of this. Now 50 kph in order to omit issue of < 500 m length. 40 kph advisory speed signs (PW-25) were planned to be installed under ERAP, and still will be.

6+163 6+551 388 50 no change

1 sharp curve @ end of section. Is centred on join to road section that will not be upgraded/realigned (KM 6+512 – see further below). 40 kph advisory speed signs (PW-25) were planned to be installed under ERAP, and still will be. Therefore, no change – OK

6+551 6+682 132 40 no change

1 very sharp curve. Was 40 kph because of this. Within Completed Section B (KM 6+512 – KM 6+997) so will not be upgraded/realigned. 40 kph advisory speed signs (PW-25) were planned to be installed under ERAP, and still will be. Therefore, no change – OK

6+682 7+107 425 60 no change 5 moderate to large curves. Issue of < 500 m length now omitted due to following change.

7+107 8+062 955 50 60

Was 50 kph due to 4 sharp to moderate curves and steep grade, but only 1 was substandard for 60 kph. Catered for by 40 kph advisory speed signs (PW-25) and steep gradient warning signs (PW-27/28) planned to be installed under ERAP, and still will be.

8+062 11+853 3,791 60 no change As-is – OK

11+853 11+975 121 50 no change

1 sharp curve. Was 50 kph because of this. Within Completed Section D (KM 11+764 – KM 13+089) so will not be upgraded/realigned. 40 kph advisory speed signs (PW-25) were planned to be installed under ERAP, and still will be. Therefore, no change – OK

11+975 13+629 1,654 60 no change As-is – OK

13+629 14+176 547 40 no change

3 very sharp curves and steep grade. Was 40 kph because of this. Within Completed Section E (KM 13+239 – KM 14+220) so will not be upgraded/realigned. 40 kph advisory speed signs (PW-25) and steep gradient warning signs (PW-27) were planned to be installed under ERAP, and still will be. Therefore, no change – OK

14+176 15+017 840 50 no change

2 sharp to moderate back-2-back (S) curves. Was 50 kph because of this, and to also transition back up to 60 kph (below). 40 kph advisory speed signs (PW-25) and steep gradient warning signs (PW-27) were planned to be installed under ERAP, and still will be. Therefore, no change – OK

15+017 19+686 4,670 60 no change As-is – OK PW = permanent warning (sign). Note: Highlighted cells reflect design speed road sections of less than 500 m in length.

Table 9: Final Design Speed Regime, LTA-GCF, 2019

STATION (FROM)

STATION (TO)

LENGTH (M)

DESIGN SPEED (KPH)

POSTED SPEED (KPH)

0+000 4+606 4,606 40 40 4+606 5+843 612 60 40/56 (KM 4+420) 5+843 6+551 708 50

56

6+551 6+682 132 40 6+682 11+853 5,171 60

11+853 11+975 121 50 11+975 13+629 1,654 60 13+629 14+176 547 40 14+176 15+017 840 50 15+017 19+686 4,670 60 Note: Highlighted cells reflect final design speed road sections of less than 500 m in length.

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7 Road Safety 7.1 Overview At time of independent road safety review, road safety features were already well addressed in design documentation. This is demonstrated by this following preliminary comment of independent road safety organisation iRAP (September 2018):

“A comparison of the baseline and design Star Rating results shows that the design greatly increases the 3-star road length for vehicle occupants from 23% to 73%. The road length achieving a 3-star or better rating for pedestrians (where present) remains the same at 77%, however the length rated at 5-stars has increased by 2.2km.”

Additional potential road safety measures were provided to the designer by iRAP. The following sub-chapters 7.2 to 7.4 cover these topics.

Guardrails are discussed in Chapter 7.5.

7.2 Road Safety Report by iRAP Introduction iRAP’s Road Safety Report, January 2019 (RSR) provided road safety Star Ratings7 of the existing CCIR alignment, as compared to the previous design prepared by SMEC under the World Bank funded ERAP stage of the project. It also provided a Star Rating of “Design + iRAP Recommendations” as a third comparator in order to demonstrate how the Star Ratings could be expected to improve if all iRAP recommendations were to be adopted. iRAP refer to this latter as a “Safer Road Investment Plan (SRIP)”. Copies of the comparable Star Rating results are providing in the following Figure 7.

Figure 7: iRAP Star Rating Comparisons

A. Maps - Baseline VS Design

7 http://irap.org/about-irap-3/methodology

http://irap.org/about-irap-3/methodology

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B. Bar Chart – Baseline VS Design VS Design + iRAP Recommendations

As can be observed, the iRAP recommendations or SRIP seek to achieve a rating of 3-stars or greater. These star ratings are separately reflected for “Vehicle Occupant” and “Pedestrian”. Each include an assessment of:

• Baseline – A desktop assessment of existing road safety. The designer provided iRAP with a BlackvueTM video file and operating program to make this assessment. Video recordings were from July 2018, for both directions of travel.

• Design – A desktop assessment of improved safety measures already accounted for in current design drawings, as also provided by the designer. These drawings were issued to the LTA during February 2018.

• Design + iRAP Recommendations – Includes iRAP proposed ‘countermeasures’ to improve the assessed road design.

Full road safety assessment details were provided in the RSR, February 2019. The following sub-chapters further analyse iRAP’s proposed countermeasures in order to determine whether or not they should be integrated into the final design, along with explanations.

7.3 Vehicle Occupant 7.3.1 Countermeasures

Further road safety improvement countermeasures for vehicle occupants included:

• Clearance of roadside hazards • Improved curve delineation • Street lighting (mid-block) provision • Wide centreline provision.

Examples of roadside hazards include hard-standing vertical objects such as trees and power poles. They present a risk to vehicle traffic, should a vehicle accidently drive off the carriageway and impact the object. Risk reduction measures include hazardous object removal, relocation further away from the carriageway, or installation of some kind of protection structure such as a guardrail.

Curve delineation improvements include additional or revised signs and lines (road markings). Some such examples include raised reflective pavement markings (RRPMs or ‘cat’s eyes’), edge marker guide posts, chevron boards, warning signs and advisory speed signs.

Street lighting improves safety through enhanced visibility at night time.

Providing a wide centreline increases separation distances between traffic travelling in opposite directions.

Further discussion of each follows.

7.3.2 Roadside Hazards

iRAP rate and report upon roadside hazards according to distance away from the edge of the carriageway. These are categorized into the following zones:

• 0 to <1 m away from edge of carriageway • 1 to <5 m • 5 to <10 m • >= 10 m.

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As there were a total of 173 numbers of 100m-long road segments containing such hazardous objects, and the iRAP provided data is a video-based visual assessment estimate only, it is not possible or practical for purposes of further risk analysis to know of and respond to each specific hazardous object on a case-by-case basis.

Instead, this iRAP reporting was noted and assessed against the typical road right-of-way (ROW) cross section of the project in order to estimate likelihood of any given hazardous object remaining within the zone of 0 to 5 m after road upgrade.

The nominal ROW width for the project is 16.0m, meaning that is it typically targeted to be 16.0m wide or 8.0m from the centreline of the carriageway. As the carriageway is 7.0m wide (two traffic lanes of 3.5m width each), a balance 4.5m remains (8.0m less 3.5m) available within the typical ROW width. This implies that all hazardous objects within the 0 to 5m zone would either need to be protected, completely removed, or relocated outside of the ROW. Using a power pole and guardrail as examples, this is visually demonstrated in Figure 8. Unlike trees which would need to be completely removed, power poles are still required to be within with the road ROW for transmission and distribution of electricity supply. The same applies for overhead communications services.

Figure 8: Roadside Hazard Zone 0 to 5m

Another consideration was that the typical 16.0m ROW is generally a minimum targeted width. It is required to be wider for horizontal curves, or may already be wider (> 16.0m) where existing ROW width already allows. In any event, all poles will wherever possible be relocated to the very edge of the ROW, which in itself can be considered a road safety risk-reduction measure. Given this, and the following other key points, it was assumed for road safety improvement implementation purposes that 1/3 (33%) of all hazardous objects will be removed or relocated outside of this 0 to 5m zone:

• Most poles will remain within the 0 to 5.0m zone, albeit on the outer-limit. • It is not practical or recommended to provide guardrails for each pole (or other hazardous object) within this zone. • As mentioned, the impracticality of conducting further detailed assessment for each potentially hazardous object.

LTA advise was additionally sort on the matter. Their conclusion was that importance of attempting to improve a sub-3-star rating to 3-stars or more should not be the driving rationale. Rather, that in consideration of these abovementioned factors, they would as a compromise be willing to accept sub-3-star ratings.

33% of the 173 iRAP identified 100m-long road segments is 58. This number of ‘adopted’ iRAP roadside hazard improvement recommendations has been back-calculated by the designer into the Strip Plan in order to provide a hypothetical demonstration of how the final design star rating now appears. This is provided in Appendix 4.

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7.3.3 Curve Delineation

iRAP identified the following 100m-long road segments for curve delineation improvements: Km 0.6 to 0.7, 5.7 to 5.8, 6.2 to 6.3, 6.8 to 6.9 & 14.6 to 14.7. All except Km 0.6 to 0.7 are sharp curves within the rural area of the CCIR8. Common to all of these in the rural area were some missing chevron signs (PW-67) for one direction of travel; being a by-product of incomplete design status. An example is reflected in Figure 9, for which iRAP identified that there were no PW-67’s reflected. The figure now reflects final design, which in this example now includes 2 chevron boards (PW-66). According to MOTSAM, PW-66’s are recommended where PW-67’s alone are considered to be insufficient. All curves (including others not necessarily identified by iRAP) have been checked and updated by the designer to reflect the MOTSAM standard recommended provision for all permanent warning (PW) sign types, for both directions of travel, and in consideration/combination of adjacent curves, straights, and sight distances.

Figure 9: Improve Curve Delineation Example (KM 6+000)

7.3.4 Street Lighting

iRAP reflected mid-block street lighting from Km 4.3 to 4.4, but as there is current design reflected street lighting up to the end of the urban area (KM 4+420), ‘mid-block’ is understood to refer to the intersection just outside of the urban area. As such, an additional luminaire (road light pole) was added to the design. This is reflected in Figure 10.

Figure 10: Final Design reflected Street Lighting (KM 4+420)

8 All rural curves are not reflected in the latest version of iRAP’s Strip Plan (refer separate Road Safety Report), but were in previous versions. They have remained accounted for in this report and as such, remain reflected in Appendix 4.

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7.3.5 Wide Centreline

iRAP reflected provision of a wide centreline for the entire urban area. This is due to the relatively higher expected traffic volumes than for the rural area. In the Strip Plan, this accounted for a total of 43 numbers of 100m-long segments identified as countermeasures.

Wide centrelines are a relatively new concept, but have been in practise in both New Zealand and Australia within this last decade. The idea is to provide wider separation distance between opposing directions of traffic, thus reducing the likelihood of cross-centreline crashes. Example images are reflected in Figure 11. These are from a February 2012 brochure of the New Zealand Transport Agency (NZTA)9 who were at the time conducting trials. They found that separation distances increased, but that there was no significant change in speed.

Figure 11: Example Wide Centrelines, New Zealand Transport Agency, February 2012

To include wide centrelines in current design would ideally, as mentioned in the RSR report, require making the carriageway wider (> current 7.0m wide) but total available ROW width is already highly optimised, and a substantial amount of detailed design and drafting rework would be required to effect this, so this was not considerable a favourable option.

Review of existing literature revealed that it is acceptable to make a wide centreline as narrow as 1.0m wide (as Figure 11 reflects). In comparing this to the typical cross section for the urban area, it was found to be possible to fit a 1.0m wide centreline and yet still have a 3.0m width available for each traffic lane (Figure 12).

9 https://www.nzta.govt.nz/assets/resources/wide-centreline-trial/docs/wide-centreline-trial-infosheet.pdf

https://www.nzta.govt.nz/assets/resources/wide-centreline-trial/docs/wide-centreline-trial-infosheet.pdf

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Figure 12: 1.0m Wide Centreline Planned for Final Design

While there is a perceived increased safety benefit of keeping opposing lanes of traffic further away from other, and additional costs to include additional line marking would be minimal, there is however concern that a wide centreline would be misunderstood by road users in the sense that they may think it is safe to pass a vehicle, or become confused about which of the 2 lines is the centreline they should stay to the left of. As a suitable alternative, a flush median strip was considered (Figure 13), but there are similar concerns with this, as road users may see it as a ‘safe haven’ for stopping in the middle of the road to make a turn, or to merge into traffic. The CCIR project road is not wide enough to falsely encourage this kind of driver behaviour, so default preference then falls back to a conventional broken white centreline. This is what is currently reflected in the drawings. Refer to Chapter 13 for further comment.

7.4 Pedestrian 7.4.1 Countermeasures

Further road safety improvement countermeasures for pedestrians included:

• New footpath provisions • Pedestrian fencing • Unsignalised pedestrian crossings

iRAP identified potential for new footpaths where they observed pedestrians to be, as viewed from the provided video files. It was a quick desktop conclusion from a ‘snap-shot’ in time, so needed to be further assessed by the designer and if recommended to include additional footpaths, ultimately decided upon by the LTA.

Pedestrian fencing was identified by iRAP as an additional safety measure for locations where pedestrians were considered likely to cross the road in an uncontrolled (and hence unsafe) manner i.e. without using a formalised pedestrian crossing. Fences discourage crossing the road. Similarly, unsignalised pedestrian crossings were identified for locations where there was considered to be potential merit in encouraging the safe road crossing of pedestrians.

Further discussion of each follows.

Figure 13: Example Flush Median Strip, New Zealand Road Code, 2015

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7.4.2 New Footpaths

iRAP identified the following 100m-long road segments for new footpath provisions. Comments from the designer were also provided.

• Km 3.5 to 3.6 – Driver side (right). Designer: existing footpath on left side. • Km 4.1 to 4.2 – Driver side (right). Designer: design footpath already proposed on left side. • Km 4.6 to 6.9 – Both sides for the 1st 100m & at Km 6.6 to 6.7, then inter-dispersed 100m-long segments for the driver

side (right). Designer: No existing or current design reflected for a footpath along this road section. To address all 100m-long segments, a complete new footpath network of about 2.3km length would have been required.

Further designer comments were provided, as follows:

Km 3.5 to 3.6 – This location is at the end of the only urban area previously upgraded by the LTA. An existing footpath is already present on the left-hand side (LHS). A bus-stop is also present in this location. Aside from civil works upgrading being a scope exclusion for this section of road (as it has already been upgraded by the LTA), there was found to be insufficient available ROW width to include one on the RHS, and for such a short section of road. No further action was therefore recommended.

Km 4.1 to 4.2 – Available ROW width is very limited throughout this urban area (up to the rural area boundary at KM 4+420), as adjacent property development is close to the road. Due to it however being an urban area, a new footpath was already reflected in the current design from KM 3+604 to KM 4+420. At KM 3+604 this new footpath adjoins the abovementioned existing footpath in the LTA completed road section. Because of the ROW constraints throughout this entire road section, it was only possible to provide a footpath on one road side. Because of road carriageway alignment limitations and other road safety considerations already made by the designer, this new footpath alternates from one side to the other along its total 820m length. As such, it includes 3 unsignalised pedestrian crossings. The section of this new footpath from KM 3+604 to KM 3+700 is reflected in Figure 14.

Figure 14: Final Design Footpath (KM 3+604 to KM3+700)

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Km 4.6 to 6.9 – This is within the ‘peri-urban’ rural area of the CCIR, as reflected in Figure 15. The urban/rural boundary at KM 4+420 is denoted by the red line. It is a steep, winding and narrow stretch of road; as-is characteristic of the road within this general area.

Figure 15: iRAP Identified Potential New Footpath – Plan View (KM 4+420 to KM 6+900)

While provision of a dedicated new footpath may serve the purpose of an additional road safety measure, limited available ROW width would dictate that it could only be on one road side, and that it would need to alternate sides due to the steep and winding terrain; thus requiring more pedestrian crossings. Unlike the urban area with its piped (buried) drainage network, another limiting factor is the generally 1.5m wide open side drains. From a safety perspective, it would be most desirable (if not essential) to locate a new footpath on the outside of these drains, as the only other alternative is to include a footpath on the current design 2.0m wide road shoulder. To locate on the outside of open side drains would require additional unavailable ROW width, as the typical ROW road cross section is already tightly constrained by having a road shoulder, open side drain, and utility corridor outside of the carriageway edge. Both options are diagrammatically reflected in Figure 16.

To place a footpath on the shoulder presents a pedestrian/vehicle delineation road safety issue. In the least, some form of physical separation would be required, and available road shoulder width would be reduced by at least one half (>= 1.0m). Ideally, the footpath should also be raised above the level of the adjacent traffic lane, but this would create a series of additional drainage issues, amongst other technical challenges.

While possible, including a dedicated footpath along this section of road is a technically challenging and

largely constrained proposition. It would have required further detailed research and investigations, including a thorough detailed design options analysis, but before even contemplating this, a social/traffic survey would need to have been undertaken. This would include interviews with local residents in order to better understand community interest and therefore, likelihood of pedestrians regularly using it. Assuming there was such interest, the LTA would then have needed to decide if it wished to pursue the further aforementioned detailed study, and be willing to accept that additional ROW width would be have been required.

The designer recommended that for immediate purposes, the priority was to move on with the current road upgrade intent, less a footpath in this location. This was subsequently agreed to by the LTA. The main reasons for this included:

• Discouraging pedestrians to walk along the road in the first place. Without a dedicated footpath, potential pedestrians will more likely use the safer option of vehicle transportation.

• High potential for project scheduling delays. If so desired, further studies can however still occur in the future.

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Figure 16: iRAP Identified Potential New Footpath – Cross Section (KM 4+420 to KM 6+900)

7.4.3 Pedestrian Fencing

iRAP identified the following 100m-long road segments for pedestrian fencing: intermittent disbursement from Km 0.1 to 4.3 (9 locations) and 17.0 to 17.1.

The 9 locations were aligned with current design pedestrian crossings, as reflected in Table 10.

Table 10: Pedestrian Crossing Schedule

S. NO.

STATION (KM) TYPE COMMENTS

1 0+119 Level Between bus stops 1.L & 1.R 2 0+529 Level Near bus stops 2.R & 2.L 3 0+857 Level Between bus stops 3.R & 3.L 4 1+254 Level Between bus stops 3.R & 3.L 5 1+781 Raised Outside of Vailima Primary School. Near bus stops 5.R & 5.L 6 2+103 Level Near bus stops 6.L & 6.R 7 2+639 Level Near bus stop 7.R 8 2+898 Level Near bus stop 7.L

9 3+660 Level To link LHS footpath with RHS footpath. Footpath changes sides for safety reasons (located on inside of sharp, steep curve).

10 3+957 Level To link RHS footpath with LHS footpath. Footpath changes sides for safety reasons (located on inside of sharp, steep curve).

11 4+226 Level To link LHS footpath with RHS footpath. Footpath changes sides for safety & serviceability reasons (located on inside of sharp curve & to better service residents & church).

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Although the addition of pedestrian fencing did not improve iRAP star rating, it was recognised to be an easy, low maintenance and cost-effective additional safety measure to implement. No additional ROW width would be required. It would at least prohibit pedestrians from ‘short-cutting’ at these planned crossing locations, and provide an additional visual queue for vehicles to slow down as they approach. An example image fenceline is provided in Figure 17.

If included, 20m long fence lines each corner of the crossing should, wherever possible, be adopted. These would need to fit within surrounding features such as bus stops and vehicle crossings. An example fit-out for the pedestrian crossing at KM 0+119 is provided in Figure 18.

Figure 18: Example Pedestrian Fence Application to Crossing (KM 0+119)

The iRAP identification for pedestrian fencing at Km 17.0 to 17.1 was due to a video-observed existing speed hump painted to resemble a pedestrian crossing. This was confirmed by the LTA not to be a pedestrian crossing, and is located in a remote rural area, so no pedestrian fencing (or crossing) was recommended or adopted.

Short lengths of pedestrian fencing can however become easily ineffective, as pedestrians intending to j-walk rather than the use the pedestrian crossing can easily do so. Such fencing can also become an additional maintenance hassle for the LTA. As agreed with LTA, no provision for any pedestrian fencing was made. Refer to Chapter 13 for further comment.

7.4.4 Unsignalised Crossing

iRAP identified the following 100m-long road segments for signalised crossings: Intermittent disbursement from Km 4.7 to 6.8, 18.3 to 18,4, and 19.7 to 19.8.

For KM 4.7 to 6.8, these were not recommended for the same explanation given regarding a new footpath network for this same road section (New Footpaths above).

Although a new footpath is now integrated on the right-hand side from KM 18+100 to KM 19+680 (as requested by the Siumu Community in support of the project – refer to Chapter 11), additionally providing pedestrian crossings around Km 18.3 to 18,4, and 19.7 to 19.8 would have served little purpose due to low expected pedestrian use and high likelihood that the crossings themselves would not be properly used. They were not therefore recommended, or adopted.

Figure 17: Example Pedestrian Fence

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7.5 Guardrails Standard W-section guardrails already exist on the CCIR. Their location, condition and extent i.e. length was taken into consideration when reviewing the entire project alignment for identification of new or replacement guardrail sections. The outcome of this review, including rationale for inclusion of new and existing guardrails is provided in Table 11.

Table 11: Guardrails

# SIDE FROM (KM)

TO (KM)

LENGTH (M)

EXISTING / PROPOSED REMARK

1 Left 3.738 3.805 67 Proposed In urban area between 2 VCs. Steep / sharp curve. Ex. house + rip-rap wall in line of travel. Resident confirmed a crash history. Tangent line offset can and will need to be closer to traffic lane than standard due to lower operating speed environment and constrained ROW width.

2 Right 4.520 4.622 102 Proposed High / steep fill on outside of steep curve

3 Left 5.225 5.280 55 Proposed Steep / sharp curve with house in line of travel close to road

4 Right 5.315 5.335 20 Proposed Steep / sharp curve + steep drop into ex. private property + close house in line of travel. G-rail to go partially into adj. side road

5 Left 5.500 5.600 100 Proposed Steep drop into open paddock i.e. high risk of vehicle continuing to roll

6 Left 5.983 6.028 45 Proposed Steep / sharp curve + moderate drop into open paddock i.e. high risk of vehicle continuing to roll

7 Left 7.350 7.440 90 Proposed Steep / sharp curve + steep drop into open paddock i.e. high risk of vehicle continuing to roll

8 Left 7.480 7.620 140 Existing Existing to be removed for road works. Undamaged parts to be delivered to LTA. Replace with brand new due to high road embankment + steep ex. terrain away from road i.e. high risk of vehicle continuing to roll

9 Right 7.980 8.050 70 Proposed Nearby steep terrain (small natural ravine)

10 Right 10.500 10.616 116 Existing Existing to be removed for road works. Undamaged parts to be delivered to LTA. Replace with new due to high / steep ex. road embankment i.e. high risk of vehicle continuing to roll

11 Left 10.530 10.616 86 Existing Existing to be removed for road works. Undamaged parts to be delivered to LTA. Replace with new due to high / steep ex. road embankment i.e. high risk of vehicle continuing to roll

As noted from the table, salvageable existing guardrail components can be returned to the LTA by the Contractor. This option to return, subject to confirmation of the LTA as the Employer during construction, is reflected in the specifications (Specification R61 Road Safety Barrier Systems). The specifications also reflect no reuse in the new works. The rationale for this is to ensure that LTA will know for certain and have on record that all guardrails on the CCIR were newly installed over the years 2020-2022 as part of this project. Reusable components can be used for any new or replacement of existing guardrails on other LTA roads as a maintenance or road safety improvement activity.

Note that no guardrails are deemed required beyond KM 10+600. They are therefore not an inclusion of CW-2, but only for CW-1.

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8 Drainage Design 8.1 Overview Drainage design is documented in the ERAP Drainage Design Report, SMEC, February 2017. The approach to drainage design included a hydrological assessment and design criteria prior to considering design options; concluding with the proposed drainage design. The detailed drainage analysis was in carried out in accordance with industry standards and current best practice, including consideration of climate change and adopting climate change adaptation measures.

It was noted that existing CCIR drainage features had clearly deteriorated and were no longer able to perform to expectations, with the following key drainage issues observed:

• Longitudinal drains (side drains) with insufficient or no capacity; causing pavement inundation. • Side road and property access driveway pipes sometimes blocked. • Discharge pits from open drains to discharge pipes often broken, compromising intake conditions for adequate passage

of water under the road. • Discharge points from side drains to outfalls subject to erosion. • Headwalls / wing walls damaged due to settlement or undermining.

The report reviewed a selection of options for drainage of the CCIR, including options for longitudinal and transverse drainage. The drainage design aimed to provide a simple and cost effective solution to provide and maintain flood resilience to the CCIR, and to ensure that the road pavement is not compromised during design flood events (DFE).

Land acquisition and establishment of drainage easements for road drainage outfalls was identified as a key issue. Locations for new drainage outfalls were identified and verified against cadastral, topographical, LiDAR and publicly available satellite imagery data, as well as visual site confirmation. No major resettlement (relocation of people or major structures) is required, and removal of privately owned fixed assets is not expected, but will be finally verified prior to installation.

8.2 Climate Change Adaptation Measures The following sub-chapters are extracted from the TA10 Climate Resilience Vulnerability Assessment, SMEC, February 2019. They were also provided verbatim in the Draft Design Completion Report (July 2019). For final status information refer to the separate Drainage Design Report, SMEC, December 2019.

8.2.1 Risk Assessment

Table 12: Drainage Vulnerability to Climate Risk

PROJECT COMPONENT

VULNERABILITY TO CLIMATE RISK

EXTREME DAILY TEMPERATURES EXTREME RAINFALL EVENTSa HIGH MEAN ANNUAL RAINFALLa EXTREME WIND

Drainage Negligible High – Short-term or immediate rapid damage caused and capacity exceeded by intense periods of rainfall

High – medium-to-long term sustained damage caused by prolonged rainfall

Negligible

Risk focus (Table 12) is on extreme rainfall events, and high mean annual rainfall.

Possible adaptation measures:

• Design drainage network for increased rainfall capacity. • For rural drainage, control drainage path flow velocities, and provide suitable erosion control measures. • Wherever possible, train surface runoff flow-paths to drain away from the road as opposed to towards road side-drains,

which are typically at the road shoulder edge e.g. use interceptor drains.

8.2.2 Current ERAP Design Inclusions

Current Status: Client approved preliminary design outcome was to adopt the recommendations of the ERAP Preliminary Design Report, including appended Drainage Design Report, Package 2. This was carried through to the current DED drawings (including notes referring to the relevant LTA specifications, and client accepted Australian standard details e.g. Brisbane City Council).

10 ADB technical assistance (TA) consultancy services, provided by SMEC over 2018

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Urban area drainage design is a fully piped network with 4 outfalls. It is almost complete (final review and revisions, plus consolidation of all final inventories and calculations only). Rural area drainage design is also well progressed, but requires more work to complete than for the urban. Both drainage schemes have accounted for the impacts of a climate change, but not necessarily in strict accordance to the recommendations of the CRWCR VASRN11 project, and for valid reasons as outlined further below. No inceptor drains are specified, as deemed not required.

Gap Analysis: As compared to possible adaptation measures (Chapter 8.2.1): • Current design has accounted for increased rainfall and runoff due to climate change. Further analysis of the current ERAP

CCIRU design against recommendations of the VA-FR [final report] are provided in Appendix 2 [of the CRVA report]. Gap analysis conclusions included: − Confirmation that use of Nafuana and Afiammalu stations instead of Apia station are more appropriate for the

project. − Review required for overly conservative rainfall intensity estimations for the central-northern part of the alignment

from KM3+604 to about KM8+000, when compared on the basis of increased rainfall with increased elevation. − Review required for both under and over conservative rainfall intensity estimations for the entire southern part of

the alignment (crest at KM 9+788 to end point at KM19+686) when compared on the basis of rain shadow effect + elevation.

− Confirmation that despite being different, the CCIRU adopted correction factor for estimating future rainfall projections is consistent with the results of the VASRN method. No change is therefore required.

− Confirmation that CCIRU proposed pipe sizes accounting for the climate change are appropriate. • For the rural drainage scheme, frequent use of rock weirs in side-drains are specified in standard drawings to mitigate

erosion by controlling flow velocities, and rock mattresses/rip-rap lining are a common theme for any discharge point. Figure 19 reflects both rock weirs and erosion control for a drop structure. These will all be geotextile lined. Geotextile lining of road-side drains to protect the road pavement will be further investigated. Pit openings will include a trash rack to minimise pipe debris blockage. Finalisation of all drainage design details is pending, but no changes to the concepts are anticipated.

• Interceptor drains are a useful way of mitigating rainfall and runoff impacts on a road by minimising the amount of water exposure to the critical part of the road – the road pavement, as road side-drains are typically (but not always) located immediately adjacent to it. In the case of the CCIRUP, width is limited, hence they are all, by default, designed to be adjacent. Due also to width constraints, opportunities for inceptor drains are likewise limited, and would most likely require additional land acquisition. Besides, there is little need for them on this project. Their inclusion is therefore not recommended.

11 World Bank. Climate Resilience of the West Coast Road Project. Vulnerability Assessment of Samoa’s Road Network. Samoa

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Figure 19: Typical Rock Weir and Drop Structure Details

8.2.3 Conclusion

Revisit rainfall intensity assumptions for north-side road section from KM 3+604 to KM 8+000, and the entire south-side (crest at KM 9+788 to end point at KM 19+686) with a view towards adopting recommended Vulnerability Assessment Final Report12 correction factors for elevation (north-side) and rain shadow effect + elevation (south-side) based on Afiamalu station data.

Finalise both urban and rural drainage designs (rural requiring the most effort).

8.3 Detailed Drainage Design Update All drainage design has now been completed, including all drawings and schedules for bidding document purposes. For further details refer to the separate Drainage Design Report, SMEC, December 2019.

12 Vulnerability Assessment – Final Report, SMEC, 2017 (VA-FR)

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9 Pavement Design ERAP design drawings reflected typical pavement design details as shown in Table 13.

Table 13: ERAP Pavement Design Typical Sections

LOCATION TYPICAL CROSS SECTION

Urban

KM 0+000 to KM 4+420

Rural 1

KM 4+420 to

KM 6+512

Rural 2

KM 6+512 to

KM 19+686

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These designs were based off detailed analysis of geotechnical investigation information performed under ERAP during 2016, and analysis of traffic count data provided by LTA from 2007 and 2013. During the TA project, ADB requested specific answers to some technical-related pavement design queries, as well as a request to validate the pavement design using an alternative to the adopted standard TRL ORN 31. In response, the designer provided a document based on comparison to Austroads. This is provided as Appendix 5, and is summarised as follows:

• Design subgrade strength: Range 8 to 14 (TRL subgrade class S4) • Traffic classification: 2.87 x 106 ESA up to KM 6+512 (traffic count location), and 1.22 x 106 ESA up to KM 19+686.

The comparison of TRL ORN 31 pavement structural design to Austroads revealed that TRL ORN 31 was slightly more conservative than Austroads in that the former required an additional 50 mm thickness of basecourse material and equal to or more thickness of total granular pavement material.

Since ERAP and this further more recent evaluation using Austroads was made, new traffic counts were performed under the TA during September 2018. This new traffic data was documented in the TA Traffic Survey Report, October 2018, and analysed (including traffic projections) in the Economic Assessment Report, February 2019. Given this update in traffic information, an updated review of the current pavement design was warranted and subsequently performed in April 2019. Both LTA and ADB were appraised of the outcome in a file note submitted on 10-Apr-19. Furthermore, these new results based on TRL ORN 31 were again compared to Austroads, with a recommendation to consider a hybrid or both standards. The rationale for this was to balance extremes from both standards, and achieve application of uniform layer thicknesses in a more consistent manner to the entire project. This note is provided verbatim as Appendix 6.

A further rapid cost analysis was performed, concluding that cost savings to project would reduce, but only marginally so, as follows:

Based purely on base and subbase layers alone:

• RN31 about US$1.6mil • Austroads about US$1.35mil • Combined about US$1.5mil

Combining standards in such a manner is an unorthodox yet innovative approach, encouraged by the initial prompting of ADB to compare the adopted design standard against an acceptable alternative (Appendix 5), and as principally supported for best new regional industry practise as evident in discussion from the Road Pavement Design for the Pacific Region, PRIF, January 2016.

The final adopted pavement design regime is as reflected in Table 14.

Table 14: Final Pavement Design Regime

FROM (STA.): KM 0+000 KM 4+420 KM 10+612 To (Sta.): KM 4+420 KM 10+612 KM 19+686

Area Urban Rural Rural Base (mm) 200 200 150

Subbase (mm) 200 150 150 Surfacing 50 mm thick AC 2-coat chip seal 2-coat chip seal

Shoulder N/A (kerbed) Cement stabilised (nom. 2.0m wide)

Cement stabilised (nom. 2.0m wide)

Further, the previous conclusion (ERAP stage) of not reusing the existing road pavement in new pavement subbase or base course layers (Chapter 5.2) was revisited. Irrespective of potential minimal cost savings to project, SMEC has however updated LTA technical Specification R22 – Earthworks to acknowledge that as long as recycled material meets the quality acceptance criteria of the specification for new works, such practice would be acceptable to project. This is reflected for reuse in the new works as subgrade (Specification R23 Subgrade Zone) or subbase material (Specification R40 Pavement Base and Subbase). It is not recommended for reuse in the base course layer, as this needs to be a top-quality material and there is unlikely to be little benefit gained/insufficient residual quantities of spec-compliant reusable material available.

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10 Alternative Material Types 10.1 Overview Under the ADB-TA some discussions took place on possible introduction of alternative material types, with the focus being on materials that could introduce some form of benefit to the project; whether it be project cost savings, environmental e.g. reduced carbon footprint, or enhanced climate resilience.

Alternative material sources discussed included:

• Nickel slag – Typically as a substitute for sand. As sand has numerous applications in a road development projects, so would nickel slag. Key road building components where it could feasibility be used include retaining structures, as a material constituent of concrete, and in granular road pavement layers.

• Waste rubber & plastic – Of interest is disposed rubber in the form of old tyres. Additionally, numerous forms of waste plastic. These waste materials are becoming more commonly used as a partial substitute for bitumen-based products i.e. road surfacing or pavement stabilising agents.

• Cement stabilisation – There is nothing new about utilising cement as a pavement layer stabilising agent, but nevertheless, possible benefits to project from a climate resilience perspective were discussed as, based on current design, there is no such provision for it.

• CarboncorTM – A proprietary road surfacing product that exhibits similar favourable properties to a hotmix asphaltic concrete (AC) surfacing layer, but is similar in cost to a standard road chip seal. It is transported, stored, and laid without the need to heat i.e. as a cold-mix.

Each of these is discussed further in the following sub-chapters.

10.2 Nickel Slag – Le SlandTM More correctly known as ferronickel slag, it is a by-product of the nickel smelting process i.e. it is a waste product.

For the Pacific region, nickel slag as a product is available for purchase from Le Nickel – SLN13, a New Caledonian-based company that is part of the Groupe Eramet or ERAMET Group. It is not known but unlikely that there are other such companies in this line of business in the region.

SLN claim to be the largest ferronickel producer in the world, with 57 kilo-tonnes of nickel being produced in 2017. Their slag product, branded as Le SlandTM, has been used for decades in New Caledonia and in more recent times, has undergone rigorous 3rd party tests and reviews that for example include operational and hazardous waste material assessments, chemical analysis, grain size distribution, bearing capacity, grain hardness and resistance.

The first export shipment of Le Sland in the Pacific was to Vanuatu in May 2018 where it was used for coastal protection works as filler-material for geotextile bags, riverbank reinforcement, trench backfill material, and as a road building material. Figure 20 shows the material in transport. According to SLN, this shipment confirmed the economic viability of the material as a suitable substitute i.e. it was reported to be a commercial success.

According to the LTA, current practise in Samoa is to extract sand from riverbeds. There is therefore an immediate environmental benefit to substituting sand with nickel slag. LTA expressed that were generally open to the idea of importing nickel slag to Samoa for use in infrastructure projects, but cautioned that it should not at this stage become a focus for immediate inclusion in the current project (CCIRUP).

10.3 Waste Rubber & Plastic Due to low material density properties, rubber can be effective in reducing the overall weight of a road pavement structure i.e. dead load of the road subgrade (live load being traffic). This would help to prolong the life of a pavement as it reduces the risk of subgrade deformation.

Rubber is also a flexible material, providing desirable deflection and crack-adverse qualities to a road pavement, but once opened to traffic it can also compress over some years.

13 www.sln.nc

Figure 20: Transport of Le SlandTM Nickel Slag, New Caledonia to Vanuatu, May 2018

http://www.sln.nc/


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A source of literature is Wayal & Wagle. Use of Waste Plastic and Waste Rubber in Aggregate and Bitumen for Road Materials, July 201314. The abstract from this paper is quoted as follows:

“Many roads agencies have been experiencing problem of premature failure of pavements like potholes, roughness, cracks and etc. which leads to poor performance of roads and its life. On the other hand, plastics, rubbers, etc. are increasing day by day. Waste like plastic bottles, polymers, cups, waste tyre’s can be re-used by powdering or blending it with crusher’s and can be coated over aggregate and bitumen by any heating process. In this study we have used polymer and crumbed rubber as a binder with respect to aggregate and bitumen. In bituminous roads, we use materials like aggregate (of various sizes), grit and bitumen. The various tests are conducted during this study on aggregates such as crushing value, impact value, abrasion value, and specific gravity and also on bitumen penetration value, ductility, softening point. The results are discussed in this paper.”

The conclusion is quoted as follows:

“As seen the above results and graphs, when 8% polymer and crumbed rubber is blended in the mix, the values of the Marshall tests viz.. Marshall Stability (kg), Flow (mm), Gmb (gm/cm3), AV (%), VMA (%), VFB (%) goes on increasing as compared to the conventional mix. This shows and proves that by adding certain amount of waste in the bitumen, it gains strength and thus becomes more durable and tough. Stone aggregate is coated with the molten waste plastics & rubber powders. The coating of plastics & rubber reduces the porosity, absorption of moisture and improves soundness. Hence the use of waste plastics & rubber tyres in the form of powder for flexible pavement material is one of the best methods for easy disposal of wastes. The use of polymer & crumbed rubber coated aggregate is better than the use of conventional aggregates in many respects. As shown in the table, it is clearly shown that there is a huge difference in the values of the mix when compared with the conventional value. In India more than 3.3 million km of road is available. If they are constructed as plastic-rubber tar road, there will be less waste plastic & waste tyres available on the road. The process is eco-friendly.”

The paper essentially confirms that from a technical stand-point, there is enough credible evidence to warrant wide-scale introduction of waste products (both plastic and rubber) for road building purposes. Cost or economic factors were not covered in this paper.

Another good initiate is presented in this video: https://www.youtube.com/watch?v=cHWYoDKYnQo. It summarizes an innovative practice in the United Kingdom of using plastic pellets in bitumen surface dressings for what they term as “plastic roads”. The pellets replace a significant amount of the bitumen content, which is typically about 10% of a road’s total material use. The company, still in a start-up phase, claims that its “plastic roads” are cheaper than conventional.

Both rubber and plastic waste use would need to be better understood as a viable option for Samoa, as, given its remoteness and small population size, it may well be an uneconomical endeavour to locally produce, and alternatively, exportation costs and logistics would also need to be understood.

In June 2014, ADB released a brief publication entitled Solid Waste Management in the Pacific – Samoa Country Snapshot. Notable points from this included:

• Little data availability on amounts and types of municipal waste, but estimates for household waste indicated 0.38 to 0.48 kgs per person per day. This data was used to estimate current waste at 20,000 tons per year based on a total Upolu Island population of 138,000. It was projected out to 2030 to be 350,000 total tons of household waste, concluding that this was a significant amount for a small island nation, even without accounting for municipal waste.

• Waste recycling is practised in Samoa homes, but there was only one commercial operation in practise. This was for metal, by a company called Pacific Recyclers. Their product is shipped to New Zealand, Australia and Korea at a rate of about twelve 20-tonne containers per month.

• “Although not yet operative, a tire-recycling center is being developed adjacent to the existing metals recycler. There are no systems in place for the effective disposal of end of life vehicles and white goods.”

• “The government is yet to develop and promote long-term, island-wide waste minimization, waste reduction, and recycling programs on Upolu, although it is committed to introducing these initiatives.”

• “In comparison with many other Pacific SWM systems, the system on Upolu is well advanced. To further improve the sector, three [these] areas of support have been identified: formulation of a national SWM strategy and development of an island-wide waste minimization and recycling program.”

The following was also found: “Samoa Tyre Recycle Ltd was also proposing to build a 4MW pyrolysis waste to energy plants and supply 25 million kwh per annum. Pyrolysis plant to convert old tyres to synthetic gas and to energy.”15. Further searches revealed that this is a private company established in 2009 and located in Apia, although no further details about their operation could be found online. By nature of its business being focused on tyre recycling, this company could be leveraged as

14 https://pdfs.semanticscholar.org/3e6b/b7fcc3a9329ecad18f31e153193e2b0a3ab4.pdf

15 http://prdrse4all.spc.int/node/4/content/samoa-waste-energy-projects

https://urldefense.proofpoint.com/v2/url?u=https-3A__www.youtube.com_watch-3Fv-3DcHWYoDKYnQo&d=DwMFAg&c=smhuqwfPwWSMyaibamWBQA&r=T9lhIFszwnRurCCfJEoeXLgcyyegQ116baGWyg3oZgs&m=qzhaBOw5KCX6yYlql0KjJ3nt1pEyuFHkFPjqUsTqPls&s=bDBaNMp2J5dV6AMeDt-zoqI6IK_bauE33-UktEC6UC8&e=

https://pdfs.semanticscholar.org/3e6b/b7fcc3a9329ecad18f31e153193e2b0a3ab4.pdf

http://prdrse4all.spc.int/node/4/content/samoa-waste-energy-projects


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a future avenue for wider-scale tire recycling, albeit with a differing end-purpose in mind than that found above for energy production.

Being close to Samoa and expected to have been developing and practicing tire recycling technology, New Zealand has accordingly been struggling with such initiatives16. Australia have been using this technology, but not on any large scale. Wide-scale application in Australia is still in the research stage17.

The LTA have expressed interest in supporting such initiatives, but as a road management authority, are also interested in addressing other queries that relate to ongoing maintenance, ability to produce locally, needs to directly import the product, cost/benefits of doing so, and importation of specific specialists that may be required, either over the short or longer term.

10.4 Cement Stabilisation As previously mentioned, this is a common road pavement stabilising agent. Its use in Samoa is however limited. LTA confirmed that the only time they have used it for road building purposes was on a section of the Vaitele Street Road Upgrade Project, where this road in urban Apia was widened from 2-lanes to 4-lanes. It was a successful exercise, and is expected by the LTA to be the best performing section of road pavement over the long-term.

This stabilisation was undertaken by local firm Ott Contractors. They are the largest contractor in Samoa. Given first time use, Ott bought in international expertise for one week to help guide the process. They also purchased their own stabilising machine to perform the works. Currently, it is the only such plant readily available in Samoa, and has been sitting idle since used for the mentioned project.

During ERAP pavement design (Chapter 9), use of cement stabilised pavement layers was considered and analysed on a parametric cost basis (per lineal metre of road, and thickness with/without cement). As no cement-treated material rates were available at the time, a 20% increase for uniform thickness per lineal metre was assumed. Based on TRL ORN 31, the analysis concluded that:

“Modified pavement layers are a commonly accepted and in many cases preferable and more economical pavement layer choice for many road construction projects worldwide. The cost analysis however revealed that this is not the case for the CCIR project, and when following the recommended pavement profiles of TRL ORN 31. In fact, based on the assumed unit rates, cement modified pavement layers would need to decrease from the currently assumed 20 % more expensive to be about the same to 10 % cheaper than their granular (unmodified) comparators. This is a highly unlikely, even improbable, scenario. Pavement modification (cement stabilised or bitumen bound) is therefore not recommended for the CCIR project road.”

More recently however, as part of the ADB-TA scope to report on project climate vulnerability, use of cement in the design was reconsidered; this time on its benefit to project as a climate change resilience material additive. The following was noted from this report:

“Similar to sub-soil drains, pavement stabilisation is also an effective means of controlling pavement moisture susceptibility, but on a wider scale. Granular layer cement stabilisation is the most obvious choice, but emulsified or foamed bitumen technologies could also be suitable alternatives. Including stabilisation should be based on its climate risk management merits versus an array of potential downside that includes but is not necessarily limited to: (i) added constructability challenges including available machinery and experienced construction and supervision personnel , (ii) increased safeguards issues (cement is caustic and can be hazardous waste), (iii) longer build time frames (additional construction task), and (iv) likely additional construction costs (material, transportation, equipment, and labour). If adopted and designed according to the current pavement design standard (TRL ORN 31), it would need to be for the subbase only and not basecourse. There may still however be merit in stabilising the basecourse instead of subbase. A third alternative is stabilisation of the road shoulders only – the only granular pavement layer exposed to the elements (unsurfaced/covered by an overlaying layer) i.e. not only is it susceptible to pavement-entrained moisture, but also surface scouring caused by excessive rainfall runoff. Cement quantities for shoulder stabilisation is about 1/3rd of the requirement for full pavement width stabilisation. Premixing for shoulders prior to transport and placement may be required, and perhaps even desirable, but of all granular road pavement components, stabilising of shoulders would appear to be the most effective and economical way of mitigating granular pavement layer climate risk vulnerability.”

The report conclusion was to further investigate possibility of including cement stabilised pavement layer(s), and to solicit client inputs.

As the previous ERAP Pavement Design Report, February 2017 already concluded that there was little merit to include stabilised pavement layers, but that the TA Climate Resilience Vulnerability Assessment, February 2019 identified road shoulders as being the most effective means of mitigating granular pavement layer climate risk vulnerability, it is recommended that substitution

16 https://www.stuff.co.nz/business/97379100/tyre-recycling-in-a-roundabout-way

17 https://weibold.com/australia-to-produce-innovative-permeable-pavement-from-scrap-tires/

https://www.stuff.co.nz/business/97379100/tyre-recycling-in-a-roundabout-way

https://weibold.com/australia-to-produce-innovative-permeable-pavement-from-scrap-tires/


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of the current design-reflected un-stabilised shoulders be replaced with cement stabilised. Figure 21 refers. Further technical details would be reflected in final design and bidding documents.

Figure 21: Cement-stabilised Road Shoulder

10.5 Coldmix asphalt – CarboncorTM CarboncorTM was developed in South Africa in 1999, and has taken it operations to Malaysia, Singapore, and more recently to Australia. In addition to use in many African and Asia countries, it has also imported material for recent projects in the region. This includes Fiji, Timor-Leste, and Australia.

Carboncor is a cold premix asphalt. It is strong, durable, waterproof and skid resistant. A recent accredited laboratory test result from Australia is provided in Figure 22. It can be mixed and cleaned up with only need to use water. It can be laid through both labour-based and machinery-based methods. No heating is required, and is not sensitive to hot, cold, or adverse weather conditions. It is environmentally friendly and contains no hazardous waste material. It is easy to use, has a long shelf life (> 12 month in plastic bags/> 6 months in bulk bags), or can be stored loose for up to 10 days on the back of a truck. Opening to traffic can occur almost immediately.

Cost benefits include:

• No need for a tack or primer coat, as it has a penetration based bonding system for all surface types. • No material wastage, given its long storage life. • No requirement to apply heat, or use solvents. There is also no mess or smell, meaning that there is less need for

protective equipment and it is faster to install. • Its relative bulk density is less than that for standard hot premixed asphalt i.e. less material per square metre. • On-site compaction can be done using light-duty rolling equipment, and equipment and labour does not need to be

specialised and skilled.


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Figure 22: Carboncor Laboratory Test Result, September 2018

Of particular note from this test result is its stability. The test result shows 22.3 kN, being well in excess of the standards’ minimum requirement of 8 kN.

In conclusion, it is a highly worthwhile consideration for adoption on the CCIRUP as an alternative material to both currently planned hotmix AC, and 2-coat chip seal.


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10.6 Conclusion A broad range of alternative material types was quickly assessed and discussed, as covered in preceding sub-chapters.

For purposes of the CCIRUP, the following conclusions were drawn:

• Economy of scale is an important factor. It would make little sense to introduce such initiatives to small value civil works contracts, such as for CW-2A & B (about $3-3.5 mil all inclusive, 2 km long road upgrade projects each). Rather, this topic is more applicable to the planned internationally advertised bidding package CW-1 ($25 mil all inclusive, 15.5 km road length).

• Introducing nickel slag and cold mix asphalt to road building are sound initiatives generally supported by the LTA, but being proprietary products (Le SlandTM and CarboncorTM respectively), their use cannot be specified in bidding documents. Procurement initiatives to overcome this problem would be to restrict use of locally available materials or reflect allowance for bidding contractors to nominate alternative technologies/materials, along with supporting documentation. A third option could be to initiate one-on-one discussions with the successful bidder. Contractor, Engineer, and Employer would all need to be satisfied with such outcome, which would likely include an adjustment to contract price. Of these three options, the 1st is not recommended as it is likely to jeopardise rather than benefit the project. This leaves the 2nd and 3rd options, both of which could feasibly be implemented. The 2nd (to encourage contractor proposals for alternate materials in supplied bids) is preferred, with the 3rd as a possible fall-back option.

• Introducing waste rubber and plastics to road building is also generally supported by the LTA, but is a topic that ideally warrants further in-depth specific study and investigations in order to obtain wider-scale support for Samoa. The scale and scope of future planned road building projects in Samoa should also be taken into consideration. Given imminent project milestones of the CCIRUP, inclusion of such initiatives was not recommended for immediate project inclusion.

• Albeit practised on only one recent LTA project, based on this project’s success; the fact that cement stabilisation is a tried-and-tested industry accepted practise for road building; and that there are climate resilience benefits to include cement-stabilised road pavement layers; this has been included in the final CCIRUP design. It has been included for the surface layer of rural road shoulders only (Figure 20), and is the exception to the economy of scale remark given above i.e. it has also been included in nationally advertised civil works (CW-2). Doing so is also in the interest of local contracting industry capacity development.

In further subsequent discussion with LTA and ADB the following options for encouragement of receiving alternative material type proposals from contractors were discussed:

1. Alternative Bids ITB 13.318: Bidders permitted to submit alternative technical solutions (including supporting documentation) to the requirements of the Bidding Document, but must first price the Employer’s design.

2. Alternative Bids ITB 13.4: Bidders permitted to submit alternative technical solutions for specific parts of the Works. Requires technical identification of the parameters Bidders would need to comply with in forming their proposals, and what the detailed technical basis of evaluation by the Employer would be.

3. Sub-clause 13.2 Value Engineering19: Contractor may at any time during the contract submit proposals for Engineer approval that would be of benefit e.g. improve efficiency or value to the Employer. If a price reduction results, the savings are halved (50%) between both parties.

No. 3 (value engineering) was firstly ruled out on the basis that it would in principle discourage proposals being offered under a competitive environment. The likelihood of either Contractor or Employer being motivated to spend time and effort on the subject post-award/commencement of works was also recognised to be low. It is, however, a recognised fall-back position that could feasibly be pursued if bidders are not forthcoming with proposed alternatives.

18 ADB. Standard Bidding Document, Procurement of Works (Large) without prequalification. Section 1: Instructions to Bidders, Clause 13. Alternative Bids. June 2018. Manila.

19 FIDIC. Conditions of Contract for Construction, Multilateral Development Bank (MDB) Harmonised Edition. General Conditions, Clause 13. Variations and Adjustments, Sub-clause 13.2 Value Engineering. June 2010. France.


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Discussion around No. 2 (ITB 13.4) then took precedence, ultimately recognising that specialist effort would need to expended in order to research and create a credible and suitable basis of performing detailed technical evaluations. The idea was seriously entertained, as it was considered to be the most motivating means to invigorate responses from potential bidders, but the final decision was made to adopt ITB 13.3. As a result, the following excerpt from standard bidding documents Section 2. Bid Data Sheet was included:

ITB 13.3 In addition to the requirements of clause 13.3 of Section 1, Bidders shall note the following:

Bidders are encouraged to consider possibilities to use alternative material types when submitting alternative bids. In the event that the lowest evaluated bidder has proposed an alternative bid, such alternative bid may be considered by the Employer only when the alternative bid price proposed is equal to or less than the price quoted for the Employer’s design in the Letter of Bid.

To encourage responses and maximise benefits of the research undertaken as part of this project by the LTA, ADB, and SMEC, it was further resolved to include an abridged version of the contents contained in this report chapter (Sub-chapters 10.1 – 10.5). This was intended to be provided as ‘supplementary information’ in the bidding documents for CW-1 (Section 6: Employer’s Requirements, Supplementary Information Regarding Works to be Procured) but since this discussion took place, ADB have engaged an independent specialist consultant who, it is understood, will look to include details that are more appropriate to adopting ITB 13.4. At time of this report submission, this new development is still ongoing and yet to be finalised between the ADB and LTA. Consequently, it has now been reflected as a new pending item in this report (Chapter 13), but for the purposes of LTA record keeping to ultimately close out in due course.

Integration of Social-related Elements

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11 Integration of Social-related Elements 11.1 Background As part of the stakeholder/community consultation process, some social-related elements were identified for inclusion in the design. Feedback from these consultations revealed that community representatives generally expected:

• A safer road, particularly through use of better road signs • Dedicated bus bays • Improved street lighting • Dedicated footpaths • Speed bumps.

The entire road design will result in a safer road, not only through more of and more suitable road signs, but also through other safety initiates that include improved road markings, site distances and safe stopping distances.

11.2 Dedicated bus bays Dedicated bus bays were already reflected in the road design. As agreed to with the LTA during ERAP, these bus bays are located within the first 3.1 km of the CCIRUP (DP-1). They are logically located to best serve commuter needs, are offset outside of the live traffic lanes, and have been detailed design to fit within numerous physical constraints such as existing side roads and private property vehicle crossings. A list of these bus bays is provided in Table 15.

Table 15: Bus Bays Locations

S. NO.

STATION (FROM)

STATION (TO)

LENGTH (M) SIDE COMMENTS

1.L 0.059 0.106 47 L Located near to the Ififi Street intersection, close to a church and supermarket. 1.R 0.115 0.158 43 R

2.R 0.546 0.589 43 R Close to a supermarket and Papauta College.

2.L 0.58 0.626 46 L

3.R 0.791 0.834 43 R Approximate mid-way point between bus stop pairs up and down station. 3.L 0.858 0.901 43 L

4.R 1.205 1.253 48 R Located near a hotel, restaurant and church.

4.L 1.31 1.353 43 L

5.R 1.789 1.834 45 R Near Vailima Primary School, close to a church, and close to the Mount Vaea hiking trail access road. 5.L 1.849 1.889 40 L

6.L 2.108 2.153 45 L Near a medical centre and close to Avele College.

6.R 2.127 2.171 44 R

7.R 2.662 2.708 46 R Near Myna’s Supermarket.

7.L 2.827 2.873 46 L

In addition, two bus stop locations were more recently (late 2018) requested by the Siumu community for the southern end of the project. These locations were for the project end point at the South Coast Road intersection (KM 19+686) and at the nearest side road (KM 18+100). These bus stops have not required special purpose design. Rather, all that is required is visible delineation of them as bus stops in accordance with the appropriate design standards, being the New Zealand MOTSAM for appropriate signs and lines (road marking). To accommodate required road marking, the Contractor will seal the 2.0m shoulder in these locations over a total length of about 30m, as like-for-like to live traffic lanes i.e. with an Employer design 2-coat chip seal20.

Because of the need for buses to stop at the same location for both directions of travel, SMEC have accounted for and reflected such provision for a total of 4 bus stops i.e. 1 on each road side, opposite each other. Provision for passengers to safely and comfortably embark/disembark from buses across/on to adjacent side drain channel has also been accounted for by specifying culverts over the half the length of the bus bay i.e. 15m long. These are positioned towards the front of the bus stop where

20 Only exception is that instead of sealing an unmodified basecourse layer, the cement stabilized road shoulders will be sealed. This can however be easily accounted for during construction in consultation with and subject to the Engineer’s prior approval and acceptance of the final works.


41



passengers will embark/disembark (Figure 23). For the right-hand (east) side, bus bays will also be directly connected across these culverts with a new footpath (Chapter 11.5).

Figure 23: Bus Stops, KM 18+130, Siumu

These are the only bus bays that have been specifically designed into and reflected in the drawings for the entire rural area. If more are required, as anticipated through prior community consultations, the same design concept in all regards can be utilised for other sites, subject to the review and approval of the Engineer and LTA as Employer. These can either be implemented as dayworks items from provisional sums or alternatively, included as additional quantities to standard relevant measure and pay items of the Bill of Quantities (BOQ). Such decision should be made by the Engineer during implementation, following Employer consent to proceed.

11.3 Bus Bay Shelters Social assessments and consultations during the ADB-TA identified a desire by the affected communities for bus shelters. Provision of bus shelters were originally considered and discussed at some length with the LTA during the ERAP stage of the project for the 1st 3.1km of the project but the initiative was abandoned due to lack of available additional ROW width at each new planned bus bay (bus stop) location. This however said, it is still possible that shelters in some shape or form (there are many existing examples in Apia) may be able to be located at or near most of the above listed bus bay locations, and further, for any new they may be agreed by the LTA for installation.

To pursue this further, it is recommended that each such location undergo formal assessment after the bulk of civil works has already been substantially completed. This way it will be much easier to consult further with residents in ‘real-time’ and to also be able to properly ‘sanitise’ the potential locations, shape, size, and form for shelters relative to each bus stop, as locating them too far away would easily result in lack of proper use and ultimately becoming a redundant investment.

For civil works implementation, a common design/architectural standard can easily be established for LTA approval, or instructed directly for use by the LTA, and implemented as a dayworks item against provisional sums. SMEC have however reflected a total of 6 bus shelters as provisional sum (PS) items, being 2 each for the following locations:

• Vailima Primary School (KM 1+790 RHS/KM 1+885 LHS) • Side road, Siumu (KM 18+105 RHS/ KM 18+135 LHS) • SCR Intersection, Siumu (KM 19+615 RHS/ KM 19+635 LHS)

The first is within CW-1 and latter two within CW-2B. Any additions can be introduced as dayworks items, or by simply applying the same PS unit rate priced by the Contractor. No bus shelters are anticipated for CW-2A (as there are very few dwellings), but if so desired, could still be introduced under dayworks rates.

Contractor requirements are addressed in Specification R71 Landscaping. The Contractor is to propose a suitable design, including shop drawings (and if applicable, photographs of similar existing) for prior Engineer and Employer endorsement.


42



11.4 Street Lighting Currently, no street lighting exists along the project road. Street lighting design was however substantially completed under ERAP for the road urban area (1st 4.42 km). These details are reflected in the road lighting (RL) series drawings of both DP-1 & 2. Connection to the main power grid, including design, will be provided by utility owner EPC. In order to simplify construction and giving due consideration for provision of other utilities, drainage, and road furniture, all road light poles are positioned on the left-hand (east) side only. Locating all poles on the one road side will especially have a hugely beneficial impact on overall utility coordination/placement. A typical example from the RL Series drawings is reflected in Figure 24. This shows poles located immediately behind the footpath. In some instances, where there is a nearby power pole, luminaire outreach poles can alternatively be mounted on the pole. In fact, doing so is preferred and recommended when a standalone street lighting pole is expected to be located too close to overhead power lines/poles. Acceptable clearance distances are documented in the drawings. It should be noted that SMEC made several attempts to coordinate this topic further with EPC, but due to no response, had no other recourse other than to assume and reflect that all street lighting poles would be standalone. This is the final outcome reflected in the drawings other bidding documents.

In the interest of enhanced night time safety for pedestrians and as highlighted in community consultations, additional lighting for select locations in the rural area was also identified. The Siumu community in particular was found to be vocal about including lighting for the southern end of the project. As a result, lighting will be included this area. Given its remoteness and intended beneficiary (pedestrians), simple solar-powered lighting (example Figure 25) was identified as being the most cost-effective (estimated US$7,000 each) and practical solution. In order to neatly tie-in with the previous mentioned 4 bus bays and dedicated footpath (next chapter), and to balance the desired safety objective against excessive investment costs, recommended provision for solar street lighting poles has been determined as follows:

• 2 each at the corner of each bus bay = 8 subtotal • Sensibly spaced for the dedicated footpath (one road side) only: about every

100m = 14 subtotal • Solar-powered lights for Siumu community area: 22 total.

Minimum specification requirements have been reflected in the specifications (Specification P2 Utility Services) for eventual proposal during construction by Contractor to Engineer for EPC and Employer approval prior to ordering.

The same details can be duplicated elsewhere on the project for other solar lighting locations not yet known or identified. Assuming a further nominal 18 locations may apply elsewhere in the rural area, total allowance in measure and pay BOQ items is 40 total (2 for CW-2A/16 for CW-1).

Figure 25: Example Solar-Powered Light Pole

Figure 24: Sample Road Lighting Position (left or east side)


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11.5 Dedicated Footpaths Currently, no dedicated footpaths exist. ERAP design drawings however reflected these for the entire urban area (1st 4.42 km). This includes footpaths both sides for the 1st 3.1 km, and one footpath alternating between road sides to the urban/rural boundary at KM 4+420. The Siumu community also more recently requested a dedicated footpath for the southern end of the project. In order to ensure ongoing support for the project, this was agreed to by the LTA. It is for the right-hand (east) side from the side road at KM 18+100 to project end point at KM 19+686, as reflected in Figure 26.

This footpath design has been fully integrated into the design drawings. Specific details are reflected in the following Figure 28, and more precisely as a result of the detailed design exercise is now located from KM 18+110 to KM 19+640 (total length 1.53km).

The footpath design is comprised of a slurry seal over 100m thick basecourse quality material. In coming to this determination, alternative designs of concrete footpath (such as for the urban area) and asphaltic concrete (AC) were considered. The concrete option was ruled out on the basis of relatively high capital costs i.e. it would cost more to construct than for AC or slurry seal, and especially for a total 1.5 km. AC was ruled out on the basis of expected shorter effective design life than for both concrete and slurry seal. This is because an AC seal performs best when it remains ‘live’, which it does so for a road pavement because it receives constant kneading from road traffic. This constant kneading helps to prolong the onset of oxidation, which is a common cause of cause of brittleness that leads to eventual failure of low-traffic volume pavement seals. In the case of this being a footpath application, and with low expected pedestrian use, a slurry seal is seen as the best design solution. A slurry seal is comprised of bitumen, water, and crusher-dust (small sized aggregate). Bitumen and water is termed as a bitumen emulsion. It is a low-capital-cost solution, easy to construct, will have an acceptable design life (before needing maintenance), and is easily maintained or improved by applying a further layer treatment or by crack sealing. Figure 27 demonstrates slurry seal application using a simple concrete mixer (for mixing and pouring) and broom to spread.

Figure 26: New Siumu Footpath – Plan View (KM 18+110 to KM 19+640)

Figure 28: New Siumu Footpath – Details (KM 18+110 to KM 19+640) Figure 27: Example Slurry Seal Application


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11.6 Speed Humps The integration of dedicated speed humps is not a common feature in the design drawings, although a few existing ones are present. One such existing example is newly installed by the LTA outside the US Embassy (Figure 29).

The only ‘speed hump’ reflected as a permanent design feature is for a raised pedestrian crossing outside of Vailima Primary School (KM 1+780). This is a specially designed reinforced concrete (RC) ramp.

As simple asphaltic concrete speed humps (Figure 29) can easily be installed by the contractor during construction, inclusion of any new or replacement of existing are best left to be further resolved during construction, following further community consultation and the final approval of the LTA as to location and number thereof. For such implementation, it is appropriate to either utilise provisional sums based on daywork item rates or add quantities to existing BOQ pay items.

11.7 Myna’s Supermarket realignment A specific request of the LTA during ERAP was to realign the CCIR around Myna’s Supermarket so that formalised off-street parking could be provisioned for this popular supermarket. At the time (2016), 5 conceptual layout designs were analysed and proposed to the LTA for consideration, with 1 option being selected as the preferred. More recently however, the supermarket relocated to a new building approx. 100m south (up-chainage) of its current location. This now has its own off-street parking facility.

Accordingly, there was talk that the old supermarket building was planned to be demolished. LTA however confirmed on 05-Mar-19 that the realignment exercise would still proceed, but that the changed objective from previous (ERAP) was to minimise land resettlement impacts to the opposing road side to the fullest extent possible whilst still achieving the objective of maximising the number of parking lots for the ‘old’ supermarket. As an additional challenge, one of the lots on the opposing road side had, since original survey in 2016, erected a new permanent building structure close to the road alignment (Figure 30). Further joint field, desktop, and design analysis by LTA and SMEC concluded that 60-degree angled parking could be accommodated without any adverse impact on this new building structure. As a result, SMEC proceeded with the design change, resulting in a slightly modified CCIR centreline realignment from about KM 2+700 to 2+900 of about 1.2m horizontal shift21, as sketched in Figure 31. The final carpark layout including resultant resettlement impacts is reflected in Figure 32.

21 And as a result, subsequent land acquisition impact improvement.

Figure 30: Myna's Realignment – Newly Erected Building Structure

Figure 29: Existing Speed Hump (US Embassy)

Figure 31: Myna's Realignment – Horizontal Shift


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Figure 32: Myna's Realignment – Final Layout and Resettlement Impacts

11.8 Papapapaitai Falls Carpark Another social-related opportunity considered under the ADB-TA was to improve the current carpark area at the viewing location of Papapapaitai Falls (Figure 33). As the initiative was falling outside of ‘true’ scope for the road upgrade and in a road section of the CCIR that is not otherwise planned to be upgraded (was previously upgraded by the LTA), it was not however pursued. Should there still however be interest in doing this, and sufficient civil works budget remains available, it could still feasibly be introduced as a dayworks item accounted for under provisional sums to one of the CW contracts. If so desired, a basic design should in the least be considered. The contractor could feasibly provide this design service, although it would be more preferable for the supervision consultant to do so.

Figure 33: Papapapaitai Falls Viewing Carpark (KM 12+100)

Conclusion

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12 Conclusion Table 16 is a checklist generated under the ADB-TA in order to identify remaining tasks required to complete technical design components. It was current as of 02-Feb-19, and is now an abridged version of Table 11, TA CCIR Engineering Review Report, June 2019. It has been updated to reflect final status (all actions now closed out).

Table 16: Task Checklist

# CHAPTER TASK DESCRIPTION STATUS 1 3.2 Right-of-way (ROW) Revise current design reflected nominal ROW width of

22.0m to 16.0 m from KM 11+014 onwards in order to minimise resettlement impacts to the fullest extent possible.

COMPLETED Change made

2 0 Table 3

Design Speed (urban) Review for safer road geometry, with target 10 kph higher than posted speed as per Austroads

COMPLETED No change required. Refer Table 8

3 Table 3 Superelevation (urban) Current design from KM 3+604 to KM 4+420 incorrectly reflects 10% max. To be revised.

COMPLETED Corrected to 5% max.

4 Table 3 Stopping Sight Distance, etc. (urban)

TBC along with design speed regime review COMPLETED No change required

5 Table 3 Design Speed (rural) Review for safer road geometry, with target 10 kph higher than posted speed as per Austroads

COMPLETED Changes made

6 Table 3 Superelevation (rural) Max. 10% TBC along with design speed regime review COMPLETED Reduced to 7% max.

7 Table 3 Stopping Sight Distance, etc. (rural)

TBC along with design speed regime review COMPLETED No change required

8 5.3 Realignment Include dedicated right turn bay to side road at KM 5+450 COMPLETED Change made

9 6.2 Design Speed Regime Assess short road sections (less than 500 m) that have been flagged as departures from the design standard (Austroads) based on setting a ‘desirable’ baseline of design speed being 10 kph more than the posted speed with a view towards a revised design speed regime change, and/or provision of specific additional signs and road marking. Additional impacts on adjacent development will be considered in conducting this exercise, along with recommendations being reported to the LTA for comment and further direction, as applicable.


10 7.3.3 Curve Delineation Implement iRAP identified countermeasures to improve curve delineation by reflecting additional chevron signs for both directions of travel (currently, for only one direction is reflected). All curves will be reviewed (not just iRAP identified locations).


11 7.3.4 Street Lighting One additional luminaire (road lighting pole) to be installed for the intersection on the rural side of the urban/rural area boundary at KM 4+420.

COMPLETED Change made

12 7.3.5 Wide Centreline Reflect in Signs & Lines (SL) series drawings for the entire urban area (4.4 km total length).

DROPPED. Refer further to see Table 17

13 7.4.3 Pedestrian Fencing Include iRAP identified countermeasure to install at current design pedestrian crossings locations (9 of).

DROPPED. Refer further to Table 17

14 8.2.3 Drainage Hydrology Revisit rainfall intensity assumptions for north-side road section from KM 3+604 to KM 8+000, and the entire south-side (crest at KM 9+788 to end point at KM 19+686) with a view towards adopting recommended CRWCR Vulnerability Assessment Final Report correction factors for elevation (north-side) and rain shadow effect + elevation (south-side) based on Afiamalu station data.

COMPLETED VA Report recommendation adopted

15 8.2.3 Drainage Design Finalise both urban and rural drainage designs (rural requiring the most effort).

COMPLETED

16 9 Pavement Design Review current pavement design based off most recent traffic count data (September 2018) and projections included in the economics analysis.


17 10.6 Alternative Material Types

• Include cement-stabilised shoulders for the rural area pavement design.

• Reflect encouragement for international contractor proposals to propose alternate materials in supplied

Cement-stabilised shoulders – COMPLETED for drawings. Pending for tech specs.

Conclusion

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# CHAPTER TASK DESCRIPTION STATUS bids, for further review of the Engineer and LTA as Employer.

Alternate materials – COMPLETED for draft bid documents.

18 11 Integrate Social-related Elements

• Complete street lighting design for the urban area. • Design and reflect inclusion of 1.6 km long footpath

for the right side at the southern end of the project (Siumu Community).

• Realign the CCIR alignment back towards existing centreline around Myna’s Supermarket (KM 2+600 to 2+900).

• Reflect planned exigency of dayworks items for inclusion of solar street lighting, sealed bus bays on shoulder, bus shelters, and speed humps all in select yet to be confirmed locations, and improvement of the Papapapaitai Falls Viewing Carpark (KM 12+100) in the rural road area.

UPDATE – solar street lighting for Siumu footpath and bus stops added as bonafide BOQ pay items, with remainder as prov. sums (PS) – locations TBC during construction. Sealed bus bays added as part of std BOQ pay items. Speed humps legitimate dayworks items, or could be added to std BOQ pay items. Engineer can introduce at any time during construction. No need to document them in official documents.

Urban area street lighting – COMPLETED

Siumu footpath – COMPLETED

Myna’s realignment – COMPLETED

Misc. items (as listed over) COMPLETED Planned dayworks exigency: Papapapaitai Falls – DROPPED, but can be added during implementation, if so desired (see Chapter 11).

Pending Items

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13 Pending Items Table 17 summarizes pending design & drafting-relevant items at time of the DRAFT Design Completion Report submission (31-Jul-19). As part of this FINAL Design Completion Report, it has subsequently been updated to reflect final status, including a new line item addition (#12).

Table 17: Pending Items

# CHAPTER TASK DESCRIPTION ACTION BY/REMARK 1 6.1 Provide Posted

Speed Limited Sign Templates

LTA were to provide templates of these Samoan-specific speed limit signs. Last requested 09-Apr-19. Not received. UPDATE – LTA supplied the templates 29-Jul-19. SMEC reviewed & improved the std. LTA drawing, returning to LTA on 22-Aug-19. LTA approved their use for the project 23-Aug-19.

LTA – If soon received, and in appropriate format, SMEC can still include in drawings but as an interim and contingency measure have instead used MOTSAM standard red and white discs with 40 kph for urban and 56 kph for rural area. FINAL OUTCOME – LTA specific signs included in final documents/LTA standard drawing updated and finalised (for Samoa-wide use).

2 7.3.5 Decide on Wide Centreline

LTA-SMEC-ADB further discussed during ADB mission Feb-19, and LTA-SMEC exchanged emails Apr-19. Alternatives of median strip and default typical broken white centreline were discussed. SMEC’s final recommendation was to stick to default broken white centreline, as both WC & MS alternates anticipated to be misunderstood and used by local drivers.

LTA – To finally decide. Refer to last email 10-Apr-19. Is for both DP-1 & 2 urban area. Part of CW-1: non-critical path. SMEC will update drawings to reflect whatever is finally decided by LTA. FINAL OUTCOME – Not adopted. Std. broken white centrelines apply, along with retroreflective raised pavement markers (RRPMs)

3 7.4.3 Decide on Pedestrian

Fencing

Discussed at same time as above stated. Decision needed is to include/exclude. SMEC final recommendation was to exclude, as iRAP safety rating will not change as a result, they are anticipated to be ineffective, and will become a further maintenance item for the LTA.

LTA – Same remark as above. FINAL OUTCOME – Not adopted.

4 8.2.3 Report on completion of

revised Drainage Hydrology approach

Accounting for recommendations of the CRWCR Vulnerability Assessment Final Report in most recent round of drainage design has occurred and is reported on in the separate Drainage Design Report.

SMEC – For both DP-1 & 2, and CW-1 & CW-2. Status update provided in Chapter 8.3, with further reporting to follow. FINAL OUTCOME – Completed. Refer to separate Drainage Design Report.

5 8.2.3 Finalise Drainage Design

Finalise both urban and rural drainage designs (rural requiring the most effort).

SMEC – For both DP-1 & 2, and CW-1 & CW-2. Critical path for CW-2 (last road section of DP-2 from KM 14+220 to 19+686). In progress. FINAL OUTCOME – Completed.

6 9 Approve revised Pavement Design

SMEC completed revised pavement design based off most recent traffic count data (Sep-18) and projections included in the ADB-TA economics analysis. It also considered alternate design standard Austroads (in addition to TRL ORN 31). As a result, a revised design based on balancing ‘extremes’ of both standards was recommended.

LTA – To approve the design. Last email from ADB to LTA 12-Apr-19 refers. ADB conveyed a position of no objection. FINAL OUTCOME – Approved, and completed.

7 1.2 Design-related Utility Relocation

Elements

Includes for e.g. typical utility corridor general arrangement for each service owner and type. SMEC have progressed research in this area, and received some minimal feedback from UOs, but more work still needs to be done. UPDATE – SMEC submitted a comprehensive Utility Relocation Report (18-Sep-19) outlining all consultations to date, what minimal information was received from UOs,

SMEC – For both DP-1 & 2, and CW-1 & CW-2. Critical path for CW-2 (last road section of DP-2 from KM 14+220 to 19+686). A proposal will be submitted for CW-2 ASAP. FINAL OUTCOME – Completed. Whilst still desirable to have more information from UOs, which can still be added to bidding documents, this now falls beyond the

Pending Items

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# CHAPTER TASK DESCRIPTION ACTION BY/REMARK conclusions drawn as a result, and appending full updated Drawings (UR Series/2 GD Series sheets) and Specifications (R92/P2 + Appendices). SMEC consequently designed the master plan for the entire utility relocation, at no additional cost to project.

responsibility of SMEC to attend to. Although not the most ideal situation, all bidding documents have been prepared in such a manner that bidding and construction can still proceed without this additional information. Will however require effective cooperation and coordination between all parties (especially the UOs). To further safeguard the LTA and minimise Contractor claim risk, it is strongly recommended that MOUs be formed between the LTA and each UO.

8 1.2 Extent of new MCIT Utility

Ducting

LTA confirmed this inclusion 05-Apr-19, and supplied some example ducting suppler product specs 26-Apr-19. SMEC understands that it is ducting desired to be installed for future planned fibre-optic use, and that installing it now is consistent with the GOS “dig once” policy (2018). It is not however aware of any other details. UPDATE – In joint LTA-MCIT-SMEC meeting Apia, 31-Jul-19 this provision was reconfirmed for inclusion in the project. The scope of what to include was also agreed: Empty pits and conduits both road sides for the urban area, and on the right (west) side for the rural area. It was also clarified that this infrastructure would not belong to MCIT, and hence, now officially referred to as “spare/future telecommunications” in bidding documents. Further details were provided in the Utility Relocation Report (18-Sep-19). SMEC consequently designed the master plan for the entire system, at no additional cost to project.

LTA – SMEC recommend that this only apply to the urban area (up to KM 4+420), that it be 1 duct of size DN100 only, but that these be on both sides of the road for the entire length, with road crossings about every 500m. LTA to please confirm this, or otherwise. Because this only applies to the urban area (all of DP-1 & the 1st 1.3 km of DP-2 – all part of CW-1), it is not critical path, but nevertheless, is a decision that should be made sometime very soon (say, by end-Jul-19). Some further fundamental considerations include type/frequency/purposes of pits, connections to private properties, treatment for Completed Section A (KM 3+127 – KM 3+604), clearance from other services, and funding for project inclusion. It is proposed for further detailed discussion when the TL will be in Apia @ end-Jul-19. FINAL OUTCOME – Completed. Still would have been desirable to have more details reflected in bidding documents, but would have required a fully-fledged detailed design exercise and output in close coordination with other utilities. Although not the most ideal situation, all bidding documents have been prepared in such a manner that bidding and construction can still proceed without this additional information. Will require effective on-site planning and coordination between Engineer and Contractor, whilst mirroring newly relocated Bluesky utilities as much as possible.

9 14 Appendix 1

Sign Design Certificates

A Certificate of Design & Certificate of Design Check is required to be completed by the LTA. LTA templates were provided in the TOR, and these have been now been refined by SMEC to include content. SMEC will sign & submit these upon finalisation of all designs. In the meantime, LTA to please confirm agreement to the content.

LTA – To review proposed design certificate content and provide feedback/acceptance prior to SMEC signing & final submission. FINAL OUTCOME – No objection from LTA. SMEC to sign and supply final versions following pending LTA-GCF overall document review/any resultant updates.

10 20

Finalisation of Schedules

Submitted separately at same time as this report under bidding documents for CW1 & CW2 respectively as Volume 4.

SMEC – The Schedules will be finalised commensurate with drawing finalisation. They will be customised to suit CW-1 and CW-2 respectively. Refer further to following remark. FINAL OUTCOME – Completed. Now awaiting LTA-GCF final review/any resultant updates.

Pending Items

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# CHAPTER TASK DESCRIPTION ACTION BY/REMARK 11 21

Finalisation of

Drawings Submitted separately at same time as this report under bidding documents for CW1 & CW2 respectively as Volume 3.

SMEC – DP-2 will be further progressed in parallel to LTA review. Critical path focus is and will still be on finalisation of the last road section 2.6 KM 14+220 – KM 19+686, in preparation for bidding of CW-2. Drainage and utilities are the 2 key outstanding items. FINAL OUTCOME – Completed. Now awaiting LTA-GCF final review/any resultant updates.

12 10.6 Alternative Material Types

ADB have engaged an independent consultant to further assess and propose appropriate details for inclusion in the final CW-1 bidding documents. Refer to Chapter 10.6 for further details.

LTA – For eventual close-out and reflection in final CW-2 bidding documents with the ADB.

Appendix 1: Design Certificates

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14 Appendix 1: Design Certificates

Our Ref: 5040021 DD Month 20XX CERTIFICATE OF DESIGN Title of Contract: Central Cross Island Road Upgrading Project (CCIRUP)

Name of undertaking: Consulting Services – Completion of Surveys and Investigations, Design and Documentation which is the subject of this Certificate: I hereby certify that the design of the above project has been carried out in accordance with sound contemporary practice and knowledge by professional Engineers experienced in road design, hydrology, drainage and stream-control hydraulics, and are qualified for MIE(Aust) or MIPE(NZ) or other recognised professional engineering organisation, namely Engineers Australia – MIE(Aust), and that the design satisfies all the requirements of the Terms of Reference as follows:

1. without amendment

Pavement design: • Transport Research Laboratory (TRL) Overseas Road Note (ORN) 31: A guide to the Structural Design of Bitumen-

surfaced Roads in Tropical and Sub-tropical Countries (TRL ORN 31). • Design of steep grades: AASHTO 2004, Part 2

Drainage design: • Austroads Guide to Road Design, Part 5: Drainage – General and Hydrology Considerations (AGRD05-13_Part 5). • Austroads Guide to Road Design, Part 5A: Drainage – Road Surface, Networks, Basins and Subsurface (AGRD05-

13_Part 5A). • Austroads Guide to Road Design, Part 5B: Drainage – Open Channels, Culverts and Floodways (AGRD05-13_Part

5B). Geometric road design • Austroads Guide to Road Design, Part 3: Geometric Design, 2017 • Austroads Guide to Road Design, Part 4: Intersections and Crossings, 2017

Street lighting design: • AS/NZS 1158. Lighting for Roads and Public Spaces.

Signs and lines design: • New Zealand Manual of Traffic Signs and Markings (MOTSAM), Part 1 and Part 2. • LTA Samoa National Road Code, 2010.

2. amended by agreement (list relevant correspondence)

Pavement design: • Additionally, to Austroads Guide to Pavement Technology (AGPT02-12) Part 2: Pavement Structural Design. As

requested by ABD in order to compare with above TOR specified design standard TRL ORN 31 pavement design. The final pavement design is a balanced outcome of both TRL ORN 31 and Austroads standard recommendations.

Signed:………………………………………...…………………(Team Leader/Senior Civil Engineer) Name: Peter Ward Date: DD Month 20XX Countersigned:………………………………………………….................(Authorised Representative) Name: Zahid Iqbal Date: DD Month 20XX

Appendix 1: Design Certificates

52



Our Ref: 5040021 DD Month 20XX CERTIFICATE OF DESIGN CHECK Title of Contract: Central Cross Island Road Upgrading Project (CCIRUP)

Name of undertaking: Consulting Services – Completion of Surveys and Investigations, Design and Documentation which is the subject of this Certificate: I hereby certify that the design of the above project has been proof-checked in accordance with sound contemporary practice and knowledge by professional Engineers experienced in road design, hydrology, drainage and stream-control hydraulics, and are qualified for MIE(Aust) or MIPE(NZ) or other recognised professional engineering organisation, namely Engineers Australia – MIE(Aust), and that and that the design satisfies all the requirements of the Terms of Reference as follows:

1. without amendment

Pavement design: • Transport Research Laboratory (TRL) Overseas Road Note (ORN) 31: A guide to the Structural Design of Bitumen-

surfaced Roads in Tropical and Sub-tropical Countries (TRL ORN 31). • Design of steep grades: AASHTO 2004, Part 2

Drainage design: • Austroads Guide to Road Design, Part 5: Drainage – General and Hydrology Considerations (AGRD05-13_Part 5). • Austroads Guide to Road Design, Part 5A: Drainage – Road Surface, Networks, Basins and Subsurface (AGRD05-

13_Part 5A). • Austroads Guide to Road Design, Part 5B: Drainage – Open Channels, Culverts and Floodways (AGRD05-13_Part

5B). Geometric road design • Austroads Guide to Road Design, Part 3: Geometric Design, 2017 • Austroads Guide to Road Design, Part 4: Intersections and Crossings, 2017

Street lighting design: • AS/NZS 1158. Lighting for Roads and Public Spaces.

Signs and lines design: • New Zealand Manual of Traffic Signs and Markings (MOTSAM), Part 1 and Part 2. • LTA Samoa National Road Code, 2010.

2. amended by agreement (list relevant correspondence)

Pavement design: • Additionally, to Austroads Guide to Pavement Technology (AGPT02-12) Part 2: Pavement Structural Design. As

requested by ABD in order to compare with above TOR specified design standard TRL ORN 31 pavement design. The final pavement design is a balanced outcome of both TRL ORN 31 and Austroads standard recommendations.

Signed:………………………………………...…………………(Proof-Checking Engineer) Name: Dhiren Singh Date: DD Month 20XX Countersigned:………………………………………………….................(Authorised Representative) Name: Zahid Iqbal Date: DD Month 20XX

Appendix 2: Realignment Options

53



15 Appendix 2: Realignment Options In the following sketches please note the main alignment grey area is 7.0m wide, orange 2.0m wide shoulders each side, and green lines representative of a 20.0m ROW (should be 16.0m). To visualise a 16.0m wide ROW, green lines less the orange shoulder width will give the general idea of target ROW width.

Note that it is a very tight fit by the time 1.5m wide side drains + 1.5m utilities are accounted for:

From centreline (CL): 3.5m lane width/2.0m shoulder/1.5m drainage/1.5m utilities = 8.5m total, being 0.5m more than for 8.0m from CL for a 16.0m ROW.

Differences either need to be made up in the drainage + utilities corridors or by widening the ROW. In finalising the design, priority will be given to achieving a min. 16.0m wide ROW width but where not possible, this will need to be wider.

None of the options presented require removal of permanent structures and resettlement of people e.g. houses.


54



15.1 KM 5+450


55



Of all 5 options presented, this is the most feasible and expected to derive the most benefits to project as while current design has been assessed as improved from a 2-star rating to 3-star if roadside hazards are addressed, a more uniform design speed can be achieved and site lines will be much improved. Existing road alignment will need to be severed, but still utilised for access to the reflected properties. A new side road connection would be required. Safest option for this side road location is as currently reflected, being the outside of new horizontal curve. No permanent or temporary structures need to be removed to accommodate this but substantially more land will need to acquired – expecting also to include the 2 small remaining paddocks on the NW side. See current cadastral (green) plus current design limit-of-works (LOW) line (white) for this area. LTA should soon decide if they want this included in updated design.


56



15.2 KM 6+000


57



Sharp S-curves could do with improvement but the reflected side road is the entrance to the Bahai Temple (LHS). Having a sharp curve here on the Apia side (northern most of the S-curves) is advantageous in order to slow vehicles down as they approach the temple carpark entrance area. Current cadastral and LOW lines are provided in the following image. This realignment is not recommended.


58



15.3 KM 6+700


59



Similar to the previous at Bahai Temple, this curve could also do with improvement but it is within one of the 5 LTA completed road sections (refer to the bell bars above for start of this section – KM 6+512), and would also create safety/site distance concerns for the property on the inside of this bend – driveway/vehicle crossing should move up-chainage towards the straight. Current cadastral and LOW lines are provided in the following image. This realignment is not recommended, mainly because it is within the extent of existing road not planned for full-width upgrade.


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15.4 KM 14+900


61



This is within the customary land area so up until only very recently we had no survey record of an existing ROW corridor, but now do. This is reflected in the following image. It would appear from this that the ‘survey’ intent was to have a more or less straight section of road, but that it was curved to avoid the dwelling currently reflected in the image.

Realigning this road section is feasible as there is very little development around it, or likely to be in the future, but other than being able to achieve a uniform design speed through this area, there is little perceived benefit in doing so. This realignment is not recommended.


62



15.5 KM 15+300


63



This curve is close to the above one. Below image shows entire area. Same comments apply.

Appendix 3: Slow Vehicle Bay (SVB) Assessment

64



16 Appendix 3: Slow Vehicle Bay (SVB) Assessment 16.1 Index Plan

• Provided for consideration as per verbal request of the LTA CEO to SMEC on Tuesday 19-Feb-19 In Apia, Samoa. Not part of the contract scope of works.

• Reflects 4 feasible locations for slow vehicle bays (SVBs). They are not passing lanes for regular use traffic. Each are reflected at a smaller scale and further commented on in the following chapters 2 thru 5. They occur from about KM 5+500 to KM9+200. All are designed to Austroads standard.

• All are intended for the up-hill/north to south direction of travel to address the issue of frequent buses (and other slow vehicles) creating queues for following vehicles and minimising potentially dangerous overtaking opportunities.

• Other parts of the alignment were considered with the following concluded: − KM 0+000 to KM 5+500 urban: not recommended nor adequate space available. − KM 9+200 to KM 19+686: little to no value for inclusion as traffic volumes on this part of the road is much less than

for the other road sections. • Each SVB includes:

− 3.0m wide lane width − No adjustment to traffic lanes widths (3.5 m each direction) − 1.0m wide shoulder − Nominal 3.0m wide corridor allowance outside of shoulder for open side drains, utilities and embankments. − Consideration of adequate sight distances and safe overtaking especially accounting for ability of slow bus driver to

remerge with thru-traffic.


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16.2 SVB No. 1: KM 5+490 to KM 5+865

• Length = 375m • Av. design gradient (vertical profile) = 9.0% (varies

from 3 to 12%) • Impact on adjacent land use:

− Severity: moderate − No. of properties impacted: 9 – but not for

formal land to acquire (see these details further below)

− No. of existing driveways impacted: 2 – 1) lot 6/11239 for what appears to be access to farmland paddock only, and 2) lot 4/11240 that is a shared access point to numerous houses (see adjacent image)

• Estimated additional land to acquire = 13.5 sqm − Severity: negligible − Comment: Can likely be designed out to zero

sqm. • Conclusion: Feasible, but should not be considered in

isolation from SVB No. 2. Refer to SVB No. 2 conclusion.


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16.3 SVB No. 2: KM 6+155 to KM 6+500

• Length = 350m • Av. design gradient (vertical profile) = 5.0% (varies from 2 to 9%) • Impact on adjacent land use:

− Severity: moderate − No. of properties impacted: 2 – but not for formal land to acquire (see these details further below) − No. of existing driveways impacted: 3 – 1) 2 for lot 1564/4784; being one each for 2 houses on this lot, and 2) lot

692/3868 for 1 house (see image below) • Estimated additional land to acquire = 13.5 sqm

− Severity: negligible − Comment: Can likely be designed out to zero sqm.

• Conclusion: Feasible, but should not be considered in isolation from SVB No. 1. SVB 1 & 2 are only about 300m apart so it makes little sense to have both of them (see combined image below). Therefore, decision focus moves to which one; basically, being before or after the Bahai Temple. Further comments apply: − Proximity of sharp curves at end of each SVB considered from a safety perspective – undesirable to have vehicles

accelerate to pass a slow vehicle then be required to immediately decelerate for a blind corner. There are 2 such sharp curves in this location: 1) KM 6+000, and 2) KM 6+500. KM 6+000 has a gentler curve before it @ KM 5+900 which is the end of SVB No. 1. This situation is considered acceptable as there is sufficient reaction time and sight lines available to vehicles. KM 6+500 curve is at the very end of SVB No. 2, so this is an undesirable/unsafe situation.

− Being the closest to Apia, SVB No. 1 is more desirable from a road user perspective as the SVB is provided sooner rather later, while climbing the hill.

− SVB No. 1 is a steeper road section than for SVB No. 2, so again, more desirable to have SVB in this location. − SVB No. 2 has 2 driveway entrances around KM 6+500, so undesirable/unsafe to terminate the SVB in this location. − SVB No. 1 has an existing skewed driveway entrance near the termination point at about KM 5+900 and another

entrance point to same property about 30m closer to the SVB from this. Skewed driveway will need to change to be at right angles to CCIR (as reflected in current design), and sight distances for this driveway will be much improved


67



with removal of existing vegetation adjacent to it and wider road including shoulders as part of current design intent. This situation is therefore considered acceptable without any additional safety measures needing to be introduced.

SVB No. 1 is preferred, especially from a safety perspective.

SVB No. 1 & 2 combined:


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16.4 SVB No. 3: KM 7+600 to KM 7+930

• Length = 340m • Av. design gradient (vertical

profile) = 7.0% (varies from 10.5% to 5.0%)

• Impact on adjacent land use: − Severity: minimal – 1 single

large grassland lot − No. of properties impacted:

1 − No. of existing driveways

impacted: 1 – lot 54/2782 being access to large grassland area and likely also to the single house on this lot (see adjacent image)

• Estimated additional land to acquire = 475 sqm − Severity: moderate − Comment: Unavoidable,

but area required can likely be reduced. • Conclusion: Desirable. Recommended.


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16.5 SVB No. 4: KM 8+900 to KM 9+185

• Length = 285m • Av. design gradient (vertical profile) = 3.5% • Impact on adjacent land use:

− Severity: minimal – 2 grassland/vegetated lots − No. of properties impacted: 2 − No. of existing driveways impacted: Nil

• Estimated additional land to acquire = 620 sqm − Severity: moderate − Comment: Unavoidable, but land not expected to

be of a high value • Conclusion: Desirable location, BUT use is expected to be

minimal given lower traffic volumes in this location, that sight lines are already suitable for safe overtaking in both directions (650m long straight), and it is near the crest of the CCIR @ KM 9+775). Therefore, not recommended.


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16.6 Conclusion

• KM 0+000 to KM 4+420 Urban area: undesirable and insufficient space to accommodate SVBs • KM 4+420 to KM 5+500 Rural area: insufficient space available. • KM 5+500 to KM 9+775 (crest of CCIR):

− SVB No. 1 recommended − SVB No. 2 not recommended due to close proximity to SVB No. 1 and safety concerns. − SVB No. 3 recommended − SVB No. 4 not recommended due to low anticipated use.

• KM 9+775 (crest) to KM 19+686 (end point) − No SVBs recommended due to low traffic volumes and several safe opportunities for passing of slow vehicles already

available in current design.

Appendix 4: Road Safety Strip Plan Engineering Assessment

71



17 Appendix 4: Road Safety Strip Plan Engineering Assessment Table 18 provides the engineering assessment of iRAP’s Road Safety Report, Appendix A: Strip Plan. The iRAP strip plan reflects recommended treatments for designer review against the proposed road design in the form of safety “countermeasures”. These countermeasures are reflected in the table, along with star ratings per 100m-long segment of road based on the information provided by iRAP (Figure 7).

The following legend applies:

The following general comments apply. Specific comments are also provided in Table 18.

Roadside hazard E.g. trees, power poles. During construction, star rating may be improved through removal or relocation of hazards further away from the edge of the carriageway. As it is impractical to make a detailed assessment of each of the iRAP reported 173 # of 100m-long segments, other factors (most notably including ROW width limitations) have been taken into consideration in order to arrive at an assumed adoption of 1/3 (33%) or 55 of 173. Further explanation is provided in Chapter 7.

Curve delineation To be improved for FINAL design Street lighting One additional luminaire (road lighting pole) to be included for intersection at KM 4+440 Wide centreline To be included in FINAL design New footpath Cost-ineffective measure to implement due to low expected use Pedestrian fencing Not beneficial enough to include. No improvement to star rating Pedestrian crossing Cost-ineffective measure to implement due to low expected use

Column Heading Road Safety ReportColumn Heading Designer Review

Not adopted for designAdopted for design1-star rating2-star rating3-star rating4-star rating5-star rating


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Table 18: Appendix 4 – Road Safety Strip Plan Engineering Assessment

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0 1 1 Wide centreline0.1 1 1 Wide centreline 1 1 Pedestrian fencing. Design crossing KM 0+119 0.2 1 1 Wide centreline0.3 1 1 Wide centreline0.4 Wide centreline0.5 1 1 Wide centreline 1 1 Pedestrian fencing. Design crossing KM 0+5290.6 2 2 Curve delineation0.7 1 1 Wide centreline0.8 1 1 Wide centreline 1 1 Pedestrian fencing. Design crossing KM 0+8570.9 1 1 Wide centreline1 1 1 Wide centreline

1.1 1 1 Wide centreline1.2 1 1 Wide centreline 1 1 Pedestrian fencing. Design crossing KM 1+2541.3 1 1 Wide centreline1.4 1 1 Wide centreline1.5 1 1 Wide centreline1.6 1 1 Wide centreline1.7 1 1 Wide centreline 1 1 Pedestrian fencing. Design crossing KM 1+7811.8 1 1 Wide centreline1.9 1 1 Wide centreline2 1 1 Wide centreline 1 Design crossing KM 2+103

2.1 1 1 Wide centreline2.2 1 1 Wide centreline2.3 1 1 Wide centreline2.4 1 1 Wide centreline2.5 1 1 Wide centreline2.6 1 1 Wide centreline 1 1 Pedestrian fencing. Design crossing KM 2+6392.7 1 1 Wide centreline2.8 1 1 Wide centreline 1 1 Pedestrian fencing. Design crossing KM 2+8982.9 1 1 Wide centreline3 1 1 Wide centreline

3.1 1 1 Wide centreline3.2 1 1 Wide centreline3.3 1 1 Wide centreline3.4 1 1 Wide centreline3.5 1 1 Wide centreline 1 New footpath. Existing footpath on passenger side (LHS)3.6 1 1 Wide centreline 1 Design crossing KM 3+6603.7 1 1 Wide centreline3.8 1 1 Wide centreline3.9 1 1 Wide centreline 1 1 Pedestrian fencing. Design crossing KM 3+9574 Wide centreline

4.1 1 1 Wide centreline 1 New footpath. Design footpath already on passenger side (LHS)4.2 1 1 Wide centreline 1 1 Pedestrian fencing. Design crossing KM 4+2264.3 1 1 Wide centreline4.4 2 2 Street l ighting4.5 URBAN BOUNDARY (Design footpath end)

4.6 2 2 Roadside hazard 2 RURAL BOUNDARY. New footpath4.7 1 1 Roadside hazard 1 Pedestrian crossing4.8 2 2 Roadside hazard 1 New footpath4.9 1 1 Roadside hazard 1 New footpath5 1 1 Roadside hazard 1 New footpath

5.1 2 2 Roadside hazard 2 New footpath. Pedestrian crossing5.2 1 1 Roadside hazard 1 New footpath5.3 2 2 Roadside hazard 1 New footpath5.4 1 1 Roadside hazard 1 New footpath5.5 1 1 Roadside hazard 1 New footpath5.6 1 1 Roadside hazard 1 New footpath5.7 2 2 Curve delineation Footpath would have to be connected5.8 2 2 Roadside hazard Footpath would have to be connected5.9 1 1 Roadside hazard Footpath would have to be connected6 Roadside hazard Footpath would have to be connected

6.1 2 2 Roadside hazard 2 New footpath. Pedestrian crossing6.2 3 3 Curve delineation Footpath would have to be connected6.3 2 2 Roadside hazard Footpath would have to be connected6.4 2 2 Roadside hazard Footpath would have to be connected6.5 2 2 Roadside hazard Footpath would have to be connected

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6.6 1 1 Roadside hazard 3 New footpath. Pedestrian crossing6.7 1 Footpath would have to be connected6.8 1 1 Curve delineation 2 New footpath. Pedestrian crossing6.97 2 2 Roadside hazard

7.17.2 1 1 Roadside hazard7.37.4 2 2 Roadside hazard7.57.67.7 1 Roadside hazard7.8 1 Roadside hazard7.9 2 Roadside hazard8 1 Roadside hazard

8.1 2 Roadside hazard8.2 2 Roadside hazard8.3 1 Roadside hazard8.48.5 2 Roadside hazard8.6 2 Roadside hazard8.7 1 Roadside hazard8.8 2 Roadside hazard8.9 1 Roadside hazard9

9.1 2 Roadside hazard9.2 2 Roadside hazard9.3 1 Roadside hazard9.4 1 Roadside hazard9.5 1 Roadside hazard9.6 1 Roadside hazard9.7 1 Roadside hazard9.8 1 Roadside hazard9.9 1 Roadside hazard10 1 Roadside hazard

10.110.2 2 Roadside hazard10.310.410.510.610.7 1 Roadside hazard10.8 1 Roadside hazard10.9 1 Roadside hazard11 2 Roadside hazard

11.1 2 Roadside hazard11.2 1 Roadside hazard11.3 1 Roadside hazard11.4 1 Roadside hazard11.5 1 Roadside hazard11.6 1 Roadside hazard11.711.8 2 Roadside hazard11.9 1 Roadside hazard12 1 Roadside hazard

12.1 1 Roadside hazard12.2 1 Roadside hazard12.3 1 Roadside hazard12.4 1 Roadside hazard12.5 1 Roadside hazard12.612.712.8 1 1 Roadside hazard12.9 2 1 Roadside hazard13 2 1 Roadside hazard

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13.1 2 1 Roadside hazard13.213.313.4 1 1 Roadside hazard13.513.6 1 1 Roadside hazard13.7 2 2 Roadside hazard13.813.9 1 1 Roadside hazard14

14.1 2 1 Roadside hazard14.2 1 Roadside hazard14.3 1 Roadside hazard14.414.5 2 2 Roadside hazard14.6 2 2 Curve delineation14.7 1 1 Roadside hazard14.8 1 1 Roadside hazard14.9 1 1 Roadside hazard15 2 2 Roadside hazard

15.1 2 2 Roadside hazard15.2 1 1 Roadside hazard15.3 2 2 Roadside hazard15.4 2 Roadside hazard15.5 2 Roadside hazard15.6 1 Roadside hazard15.7 1 Roadside hazard15.815.916

16.1 1 Roadside hazard16.2 1 Roadside hazard16.3 1 Roadside hazard16.416.516.6 2 Roadside hazard16.7 1 Roadside hazard16.8 1 Roadside hazard16.9 2 Roadside hazard17 2 Roadside hazard 1 Pedestrian fencing. Remote area. No planned footpath

17.1 2 Roadside hazard17.2 2 Roadside hazard17.317.4 1 Roadside hazard17.5 1 Roadside hazard17.6 2 Roadside hazard17.7 2 Roadside hazard17.8 2 Roadside hazard17.9 2 Roadside hazard18 2 Roadside hazard

18.1 1 Roadside hazard NOTE: New footpath to include as per Siumu community request18.2 1 Roadside hazard NOTE: New footpath to include as per Siumu community request18.3 2 Roadside hazard 1 Pedestrian crossing18.4 2 Roadside hazard NOTE: New footpath to include as per Siumu community request18.5 1 Roadside hazard NOTE: New footpath to include as per Siumu community request18.6 2 Roadside hazard NOTE: New footpath to include as per Siumu community request18.7 2 Roadside hazard NOTE: New footpath to include as per Siumu community request18.8 1 Roadside hazard NOTE: New footpath to include as per Siumu community request18.9 1 Roadside hazard NOTE: New footpath to include as per Siumu community request19 1 Roadside hazard NOTE: New footpath to include as per Siumu community request

19.1 2 Roadside hazard NOTE: New footpath to include as per Siumu community request19.2 NOTE: New footpath to include as per Siumu community request19.3 2 Roadside hazard NOTE: New footpath to include as per Siumu community request19.4 2 Roadside hazard NOTE: New footpath to include as per Siumu community request19.5 NOTE: New footpath to include as per Siumu community request19.6 2 Roadside hazard NOTE: New footpath to include as per Siumu community request19.7 1 Pedestrian crossing19.8 1 Roadside hazard

93 80 5 1 43 222 16 2 10 7 3529 29 5 1 43 107 0 0 11 0 11

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Appendix 5: Pavement Design Review – TRL Oversea Road Note 31 VS Austroads

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18 Appendix 5: Pavement Design Review – TRL Oversea Road Note 31 VS Austroads

18.1 Purpose This note is provided in response to the following from ADB about the road pavement design:

10-Oct-18: “In continuation of pavement design discussion, please refer to below document. Long -term behavior of subgrade CBR is very critical variable to be well understood and it is especially so when climate-change impacts considered [refer to Chapter 18.2]. While this review concludes that RN31 is credible design method for Pacific region, it would be important that we have validated the pavement design against one of the other methods that we think would be best to check against”. [refer to Chapter 18.3].

https://www.theprif.org/documents/regional/transport-land/road-pavement-design-pacific-region

09-Oct-18: “Discuss and demonstrate how TRL pavement design responds to 20% increase in rainfall with climate change impact considered.” [refer to Chapter 18.4]

09-Oct-18: “Design report mentions that CBR value of 8% was assumed. Has this been confirmed and will this value change with climate change impact considered? Similarly, discuss increased risk to cut-and-fill slopes due to increase in rainfalls and what design measures are provided.” [refer to Chapter 18.5].

18.2 Long-term behavior of subgrade CBR Material testing of the existing CCIR was comprehensively reported upon in the Geotechnical Investigation Report. Field tests included 82 Nos. of DCPs, which were reported upon as inferred CBRs. 8 Nos. of site samples were also taken to the LTA lab for CBR testing.

Lab samples were soaked for 4-days, as per the requirements of AASHTO T-193. Soaking simulates a pavement expected to receive moisture i.e. to become soaked. 4-days is commonly accepted industry practice as most soils will fully soak within this period.

AASHTO T-193 is a test to determine soil strength or in other words, its load-bearing capacity. It therefore simulates a soils long-term load-bearing behavior.

The inferred CBR results derived from DCP tests are useful to compare to the lab CBR results, but are less reliable. The results are summarized in Chapter 18.3.2.

18.3 Pavement design validation from another acceptable method Empirical method of Austroads has been used, as one of the other recognized methods from the received report (Road Pavement Design for the Pacific Region, PRIF, January 2016).

https://www.theprif.org/documents/regional/transport-land/road-pavement-design-pacific-region


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18.3.1 Section 8. Design of Flexible Pavements – FLOW CHART


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18.3.2 Section 5. Assessment of Design Subgrade CBR

Range, say 8 to 14.

18.3.3 Section 7. Prediction of Design Traffic

18.3.4 Section 8.3.1 Determination of Basic Pavement Thickness

• Is Figure 8.4 applicable i.e. 105 – 108 ESA? Is 106, so YES.

• Use Figure 8.4:


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• Min. thickness of base material: 150 mm. • Thickness of granular material: 250 mm (CBR 14) to 350 mm (CBR 8). • Therefore: 150 mm basecourse + 100 to 200 mm subbase.

Current design – highest traffic:

400 mm total RN31 VS 350 mm [at worst] from Austroads.

Current design – lowest traffic:

350 mm total RN31 VS 350 mm [at worst] from Austroads. Note that RN31 calls for an additional 50mm of basecourse.


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18.3.5 Section 8.3.2 Pavement Composition

• Performance testing during construction as per LTA specification R40 will require achieving min. 80% CBR for base (Base

Class B) and min. 30% CBR for subbase (Subbase 1), so is acceptable.

• As per LTA R40 specification other compliance testing will include grading, Atterberg’s limits, flakiness, wet/dry strength,

etc.

• AC of 50mm thick is specified in the urban area but it is not considered for pavement design purposes to be contributing

towards pavement strength, so has not had any bearing on the thickness of granular material to be used.

18.3.6 Conclusion

As can be seen from Chapter 18.3.4, comparing RN31 to Austroads reveals that RN31 is slightly more conservative than Austroads i.e. RN31 requires 50 mm additional basecourse (200mm VS 150mm) and equal to or more thickness of total granular pavement material.

18.4 How TRL pavement design responds to increased rainfall It does not persay respond to increased rainfall, but instead relies upon assumptions about the expected subgrade moisture condition.

From RN31 Section 3. SUBGRADE:

“For designing the thickness of a road pavement, the strength of the subgrade should be taken as that of the soil at a moisture content equal to the wettest moisture condition likely to occur in the subgrade after the road is opened to traffic.”

From RN31 Section 3.2 DETERMINING THE SUBGRADE STRENGTH:

“If saturated subgrade conditions are anticipated, the compacted samples for the CBR test should be saturated by immersion in water for four days before being tested. In all other cases when CBR is determined by direct measurement, the CBR samples should not be immersed since this results in over design.”

In the case of the CCIR, we have assumed a worst-case scenario of full saturation, and hence the 4-day soaked CBR lab test was adopted (Chapter 18.2).

It is also worthy to note that:

• The CCIR is generally a steep road, so incidents of water ponding are already highly minimised. • Where side drains are required, their invert will always be below road pavement subgrade level, thus creating an effect

of positive drainage for both surface and pavement-entrained water. • Cross-drains and outfalls are frequently provided.


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18.5 Has CBR 8% been confirmed, will it change, and what is the risk to cut-and-fill slopes? Refer to Chapter 18.2 for confirmation of CBR 8%. It already simulates a soaked condition so in the context of how this question is asked, no it will not change due to increased rainfall. It must however be noted that irrespective of rainfall, every material sample will give differing CBR results, such as is the case for each of the 8 samples that were taken. This is due to sample material variability i.e. not rainfall. CBR 8% was the lowest recorded value, but not unusually so, so ‘assuming’ it as the design value was and still is considered suitable.

Generally speaking, it could be expected that more frequent and intense rainfall events will cause more damage to cut-and-fill slopes i.e. more slips requiring maintenance intervention, but design cut-and-fill slopes of any significance on the CCIR is minimal, will be grassed-lined, and no slopes will be steeper than 1:1. Based on the existing CCIR cut-and-fill slopes, these measures are deemed to be adequate, and any such damage is likely to be addressed by the LTA following extremes rainfall events under emergency maintenance works.

Appendix 6: Pavement Design Review – Update for new Traffic Count Data & Forecasting

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19 Appendix 6: Pavement Design Review – Update for new Traffic Count Data & Forecasting

20190410 SAM_CIRD_5040021

19.1 Purpose This note is provided to both the LTA and ADB for input comments based on the outcome of revised pavement design for the CCIRUP. This revision has been necessitated by updated traffic count data and subsequent new traffic growth projections.

19.2 Background Previous traffic projections for pavement design purposes performed under the World Bank funded ERAP stage of the project (2016/2017) were based on LTA supplied data from traffic counts performed in 2007 and 2013, and the TOR specified design standard RN31.

Under the ADB funded stage of the project, new traffic counts were conducted in the same three locations during September/October 2018.

The three traffic count sites included:

1. U-TC003 at Valima: KM 1+250 2. U-TC019 at Tiapapata: KM 5+650 3. U-TC020 at Siumu: KM 19+686

ERAP pavement design assumed two distinct ‘traffic assessment sections’.

Year 2013 average daily traffic (ADT) figures from the three traffic count sites were used to determine annual average daily traffic (AADT) figures for each traffic assessment section by computing the average from both count sites e.g. traffic assessment section No. 1 was based on the average values from U-TC003 and U-TC019. The same approach was applied for determining % of heavy class vehicles (HCVs).

The results were as follows:

For the 20-year pavement design life, a uniform traffic growth rate of 4% p.a. and 0.8 equivalent standard axles (ESA) per HCV was assumed.

Year 1 for traffic assessment section No. 1 was determined to be 2019, and for No. 2 to be 2022.

The results were as follows:

On 10-Oct-18 ADB requested validation of this RN31-based pavement design by using another acceptable method. The report Road Pavement Design for the Pacific Region, PRIF, January 2016 was supplied by ADB, and referred to for this purpose. Along with RN31, the empirical method of Austroads was included, so was used for this comparison purpose.

The assessment concluded that RN31 was more conservative than Austroads, as Austroads specified 50mm less thickness of basecourse than RN31 for the same input parameters of traffic (tabulated above), and subgrade strength (worst case of CBR 8%).

19.3 New pavement design (RN31 2019) 19.3.1 Traffic assessment sections

Three traffic assessment sections instead of two have now been considered as more appropriate, for the following reasons:

• 2018 counts reflected far higher traffic volumes for U-TC003 than the other two sites (3.5 to 6 times more). This scale of difference was not apparent in the previously assessed 2017/2013 data.

AADT (HCVPD)

From To Environment Count Site/s 2018 (2-lane) 2018 (1-lane) 2018 (1-lane)

1 KM 0+000 KM 6+512 Urban/Rural U-TC003/19 1,745 873 30.0 2622 KM 6+512 KM 19+686 Rural U-TC019/20 982 491 20.0 98

Traffic Assessment Section No.

Location AADT (VPD)% HCV

From To1 KM 0+000 KM 6+512 6.512 6.035 2.87 T4 (1.5 - 3.0) S4 (8-14) 200 200 4002 KM 6+512 KM 19+686 13.174 9.981 1.22 T3 (0.7 - 1.5) S4 (8-14) 200 150 350

19.686 16.015

Upgrade Length (km)

ESA (x 106)

Traffic Class

Subgrade Class

Base (mm)

TRL ORN 31 Subbase

(mm)Total (mm)Traffic Assessment

Section No.Location Section

Length (km)


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• U-TC019 traffic volumes are almost twice as high as U-TC020. • Further land development on the outskirts of urban Apia is expected, but to what extent is not entirely clear. Satellite

imagery analysis reveals that this could occur up to as far as about KM 9+200, where the last ‘main’ side road (unnamed) from the CCIR is located.

• From this location onwards, current and future land development is expected to be much less (negligible) given its remoteness and predominance as customary owned land.

KM 10+612 is chosen instead of KM 9+200 as this is where new pavement will join existing at one of the five previously completed road sections by LTA.

19.3.2 ADT & % HCV per section

Given the now three new traffic assessment sections, it has also been determined appropriate to apply exactly the 2018 ADT figures and % HCV values from each of the three count sites to each of the traffic assessment sections.

The new 2018 AADT & % HCV results are summarized as follows:

19.3.3 New growth rates

Instead of 4% p.a., traffic growth projections from the Economic Analysis Report, April 2019 have now been adopted. This includes an assumed growth rate of 3.5% for 2018 to 2024, and 2.0% from 2025 onwards.

0.8 ESA per HCV has remained unchanged.

19.3.4 New analysis period

20-year design life still applies, but instead of staggered Year 1 assumptions of 2019 and 2022, year 2023 has now been adopted as Year 1, with the 20th year now being 2042.

19.3.5 New results

The new pavement design results are summarized as follows:

For visual reference, relevant RN31 chart extract for all traffic classes is provided as follows:

Up to KM 4+420 (urban/rural area boundary), 50mm more subbase is required because of the higher traffic, but this is offset by reductions in overall pavement thickness for new section No. 3 – 25mm less pavement thickness overall, with 50mm less basecourse thickness (being more expensive than subbase).

If to strictly adopt RN31, this above tabulated pavement design regime is recommended to be adopted, but before deciding, comparison with Austroads is once again revisited, as follows.

AADT (HCVPD) From To Environment Count Site 2018 (2-lane) 2018 (1-lane) 2018 (1-lane)

1 KM 0+000 KM 4+420 Urban U-TC003 6,878 3,439 20.5 7052 KM 4+420 KM 10+612 Rural U-TC019 1,944 972 18.3 1783 KM 10+612 KM 19+686 Rural U-TC020 1,184 592 13.1 77

Location% HCV

AADT (VPD)Traffic Assessment Section No.

From To 1 KM 0+000 KM 4+420 4.420 3.933 5.67 T5 (3.0 - 6.0) S4 (8-14) 200 250 450 2 KM 4+420 KM 10+612 6.192 5.707 1.43 T3 (0.7 - 1.5) S4 (8-14) 200 150 350 3 KM 10+612 KM 19+686 9.074 6.366 0.62 T2 (0.3 - 0.7) S4 (8-14) 150 175 325

19.686 16.005

Upgrade Length (km)

Location Section Length (km)

Traffic Assessment Section No.

Subgrade Class

ESA (x 106)

Traffic Class

Base (mm)Subbase

(mm)Total (mm)

TRL ORN 31


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19.4 New Austroads comparison The same input parameters have been used for comparison. These are reflected in the following Austroads chart and table:

They compare with RN31, as follows:

This once again confirms that RN31 is more conservative than Austroads. The key difference is in the thickness of basecourse.


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19.5 Conclusion As can be seen from the Austroads chart, 200mm thick basecourse is only specified for high design ESA (108 or 100 million), being a magnitude of about 17.5 times more than the highest anticipated ESA for this project (5.67 x 106 or 5.67 million).

Irrespective of pavement design standard adopted (RN31 or Austroads), achieving material quality expectations of each and as per the technical specifications is fully expected.

Bearing these points in mind, adopting an unorthodox yet innovative approach of combined standards is presented for final consideration, as follows:

As a result, a balance of extremes from both standards is achieved, and uniform layer thicknesses are applied in a more consistent manner to the entire project.

These reflect no change from the original ERAP design up to KM 10+612, but 50mm less basecourse from this point onwards for a total pavement upgrade length of about 6.4 km.

If not supported, then fully adopting RN31 recommendations is (Chapter 19.3.5).

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Documents

Central Cross Island Road Upgrading Project: Design