4. Method Statement 20110321

ROAD DEVELOPMENT AUTHORITY

MINISTRY OF HIGHWAYS & ROAD DEVELOPMENT

THE DEMOCRATIC SOCIALIST REPUBLIC OF SRI LANKA

GREATER COLOMBO URBAN TRANSPORT

DEVELOPMENT PROJECT

OUTER CIRCULAR HIGHWAY (OCH) TO THE CITY OF

COLOMBO PROJECT NORTHERN SECTION-1

SCHEDULE VIII

Method Statements (Rev.1)

21 March 2011

Prepared by

TAISEI CORPORATION

Greater Colombo Urban Transport Development Project SCHEDULE VIII

OCH to the City of Colombo Project Northern Section-1 Table of Contents

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Table of Contents

1. PART 1:

CONDITIONS FOR CONSTRUCTION METHODS _____________________________ 1

1.1 TECHNICAL PREREQUISITES FOR CONSTRUCTION __________________________ 1

1.1.1 Work Programme _____________________________________________________ 1

1.1.2 Temporary access roads ________________________________________________ 2

1.1.3 Additional points to be emphasized _______________________________________ 2

1.2 PROJECT DESCRIPTION ___________________________________________________ 5

1.2.1 Introduction __________________________________________________________ 5

1.2.2 Location and objectives _________________________________________________ 5

1.2.3 Major features of Northern Section-1 _____________________________________ 5

1.2.4 Construction schedule __________________________________________________ 7

1.2.4.1 General _____________________________________________________________ 7

1.2.4.2 Preparing and maintaining firm and stable working formation __________________ 7

1.2.4.3 Timely implementation of preliminary works _______________________________ 9

1.2.4.4 Implementation of embankment works in appropriate execution speed __________ 11

1.2.5 Environmental Management Plan (EMP) _________________________________ 11

1.2.6 Safety and public relations _____________________________________________ 14

1.3 PROCESS CONDITIONS ___________________________________________________ 16

1.3.1 Workable days _______________________________________________________ 16

1.3.1.1 Working conditions based on type of work and precipitation __________________ 16

1.3.1.2 Holidays in Sri Lanka ________________________________________________ 16

1.3.1.3 Workable days and operating rate _______________________________________ 16

1.3.2 Material conversion factors ____________________________________________ 18

1.3.3 Production rates ______________________________________________________ 18

1.3.3.1 Earthworks _________________________________________________________ 19

1.3.3.2 Paving works _______________________________________________________ 19

1.3.3.3 Bridgeworks ________________________________________________________ 20

1.4 DESCRIPTION OF CRITICAL PATH WORKS _________________________________ 21

1.5 PARTICULAR CONCERNS _________________________________________________ 24

1.5.1 Handover procedure __________________________________________________ 24

1.5.2 Defects liabilities _____________________________________________________ 26



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2. PART 2:

CONSTRUCTION METHODS WITH CONSTRUCTION RESOURCES __________ 28

2.1 GENERAL ________________________________________________________________ 28

2.2 OVERALL WORKFLOW ____________________________________________________ 28

2.3 COMMON WORK ITEMS ___________________________________________________ 32

2.3.1 Temporary works ____________________________________________________ 32

2.3.2 Utility relocation works ________________________________________________ 35

2.3.3 Excavation, embankment and hauling works ______________________________ 36

2.3.4 Drainage works ______________________________________________________ 37

2.3.5 Paving works ________________________________________________________ 41

2.4 ENVIRONMENTAL PROTECTION IN THE OCH PROJECT _____________________ 46

2.5 TRAFFIC MANAGEMENT AT NATIONAL ROADS A1, AB10 AND B214 ___________ 50

2.6 SOFT GROUND TREATMENT ______________________________________________ 51

2.6.1 General _____________________________________________________________ 51

2.6.2 Proposed disposal locations ____________________________________________ 65

2.6.3 Surcharge ___________________________________________________________ 65

2.6.4 Preloading __________________________________________________________ 66

2.6.5 Monitoring __________________________________________________________ 66

2.7 BORROW MATERIALS AND AGGREGATE QUARRIES _________________________ 67

2.7.1 General _____________________________________________________________ 67

2.7.2 Planning and transportation ____________________________________________ 67

2.8 CONSTRUCTION METHOD OF BRIDGES AND VIADUCTS _____________________ 70

2.8.1 Summary ___________________________________________________________ 70

2.8.2 Workflow ___________________________________________________________ 72

2.8.3 Working hours _______________________________________________________ 73

2.8.4 Piling works _________________________________________________________ 73

2.8.5 Substructure _________________________________________________________ 78

2.8.6 Superstructure _______________________________________________________ 80

2.8.6.1 PC I-girder bridges ___________________________________________________ 80

2.9 CONSTRUCTION METHOD OF KELANI RIVER BRIDGES (STA.16+300) _________ 94

2.10 THERMAL CONTROL FOR STRUCTURAL MASS CONCRETE __________________ 97

3. PART 3:

CONTRACTORS QUALITY MANAGEMENT PLAN _________________________ 98

3.1 SCOPE AND PURPOSE OF PROJECT QUALITY MANAGEMENT PLAN __________ 98



iii

3.2 QUALITY OBJECTIVES OF THE PROJECT ___________________________________ 98

3.3 PROJECT QUALITY MANAGEMENT SYSTEM ________________________________ 99

3.3.1 Engineering/Design Quality Management & Control _______________________ 99

3.3.2 Procurement Quality Management & Control ____________________________ 100

3.3.3 Construction Quality Management & Control ____________________________ 100

3.4 INSPECTIONS AND TESTS PLAN __________________________________________ 102



iv

List of Figures

Fig. 1.2.4.2.1 Example of a plan of working formation around bridge piers __________________ 8

Fig. 1.2.4.2.2 Typical section of working formation ______________________________________ 9

Fig. 1.2.5.1 Example of temporary staging for flood ____________________________________ 13

Fig. 1.2.5.2 Disposal of peat into hollow and covering it by topsoil _________________________ 14

Fig. 1.4.1 Work Programme Critical Path Activities ___________________________________ 23

Fig. 1.5.1.1 Handover procedure ____________________________________________________ 25

Fig. 1.5.2.1 Remedy work during the defect liability period _______________________________ 27

Fig. 2.2.1 Overall project plan ______________________________________________________ 29

Fig. 2.2.2 Work division into working sections _________________________________________ 30

Fig. 2.2.3 Overall workflow ________________________________________________________ 31

Fig. 2.3.1.1 Example of temporary road outside ROW (box culvert) ________________________ 33

Fig. 2.3.1.2 Example of temporary road outside ROW (overpass bridge) ____________________ 34

Fig. 2.3.4.1 Typical section of pipe culverts and construction sequence _____________________ 38

Fig. 2.3.4.2 Typical section of ditches and construction sequence __________________________ 39

Fig. 2.3.4.3 Typical section of catch basins and construction sequence _____________________ 40

Fig. 2.3.5.1 Pavement structure (subbase course) _______________________________________ 42

Fig. 2.3.5.2 Pavement structure (aggregate road base) __________________________________ 43

Fig. 2.3.5.3 Asphalt pavement structure ______________________________________________ 44

Fig. 2.6.1.1 Soft ground treatment Type-A ____________________________________________ 52

Fig. 2.6.1.2 Soft ground treatment Type-B ____________________________________________ 52

Fig. 2.6.1.3 Sequence of works for soft ground treatment Type-A and Type-B ________________ 53

Fig. 2.6.1.4 Soft ground treatment Type-C ____________________________________________ 54

Fig. 2.6.1.5 Sequence of works for soft ground treatment Type-C __________________________ 56

Fig. 2.6.1.6 Soft ground treatment Type-D ____________________________________________ 56

Fig. 2.6.1.7 Sequence of works for soft ground treatment Type-D and Type-G _______________ 58

Fig. 2.6.1.8 Soft ground treatment Type-E ____________________________________________ 59

Fig. 2.6.1.9 Soft ground treatment Type-F ____________________________________________ 60

Fig. 2.6.1.10 Sequence of works for soft ground treatment Type-E and Type-F _______________ 62

Fig. 2.6.1.11 Soft ground treatment Type-G ___________________________________________ 63

Fig. 2.6.1.12 Soft ground treatment Type-H ___________________________________________ 63

Fig. 2.6.1.13 Sequence of work for soft ground treatment Type-H _________________________ 65

Fig. 2.7.2.1 Locations of supply and disposal plan ______________________________________ 69

Fig. 2.8.2.1 Workflow of bridgeworks ________________________________________________ 72

Fig. 2.8.4.1 Reverse circulation method (RCD) ________________________________________ 76



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Fig. 2.8.4.2 All casing method (AC) _________________________________________________ 77

Fig. 2.8.5.1 Steel support system for overhanging column head of viaduct ___________________ 79

Fig. 2.8.6.1.1 General arrangement of temporary facility) ________________________________ 81

Fig. 2.8.6.1.2 Precast yard outline ___________________________________________________ 82

Fig. 2.8.6.1.3 Rebar jig detail _______________________________________________________ 83

Fig. 2.8.6.1.4 Rebar cage lifting frame _______________________________________________ 84

Fig. 2.8.6.1.5 Typical section of formwork system ______________________________________ 85

Fig. 2.8.6.1.6 Sequence of PC I-girder fabrication ______________________________________ 86

Fig. 2.8.6.1.7 Workflow for PC I-girder bridges ________________________________________ 87

Fig. 2.8.6.1.8 Direct setting method __________________________________________________ 88

Fig. 2.8.6.1.9 Election Sequence by TEG (1) __________________________________________ 89

Fig. 2.8.6.1.10 Election Sequence by TEG (2) _________________________________________ 90





Fig. 2.8.6.1.15 Support system for cross beam works ____________________________________ 93

Fig. 2.9.1 Workflow for Kelani River bridges __________________________________________ 94

Fig. 2.9.2 Construction of temporary bridge and platform ________________________________ 95

Fig. 2.9.3 General section of double sheet pile cofferdam ________________________________ 96

List of Tables

Table 1.3.1.1.1 Working conditions based on type of work and precipitation (p) ______________ 16

Table 1.3.1.3.1 Workable days and operating rate ______________________________________ 17

Table 1.3.2.1 Material conversion factors _____________________________________________ 18

Table 1.3.3.1.1 Production rates for earthworks ________________________________________ 19

Table 1.3.3.2.1 Production rates for paving works ______________________________________ 19

Table 1.3.3.3.1 Production rates for structural works ___________________________________ 20

Table 1.4.1 Critical path activities for the Project based on 48-month schedule _______________ 22

Table 2.6.1.1 Grading requirement for gravel mat and GCP material_______________________ 51

Table 2.7.2.1 Details of quarry areas _________________________________________________ 67

Table 2.7.2.2 Details of borrow pits __________________________________________________ 68

Table 2.7.2.3 Details of dumping sites ________________________________________________ 68

Table 2.8.1.1 List of bridges ________________________________________________________ 71


OCH to the City of Colombo Project Northern Section-1 Part 1

TAISEI CORPORATION Page 1 of 108

1. PART 1:

CONDITIONS FOR CONSTRUCTION METHODS

1.1 TECHNICAL PREREQUISITES FOR CONSTRUCTION

The construction plan described here in Schedule VIII: Method Statement has been based on the

technical prerequisites set forth herein.

These technical prerequisites arise from the absolute necessity to carry out the Works as shown below.

Without the fulfillment of these technical prerequisites the Contractor cannot physically carry out the

Works within the scope of the Contract and to the satisfaction of the Employer.

Our financial proposal is also contingent on the fulfillment of these technical prerequisites. We urge

the Employer not to treat these prerequisites as a conditional offer as per Clause 18.1 of Part 2, Vol.

I: Instructions to Bidders. Instead, the Employers attention is drawn to the fact that these

prerequisites are an absolute must from technical point of view in order to enable the physical

possibility of carrying out the Works as supported by technical evidence.

1.1.1 WORK PROGRAMME

Location in Contract

Document

Time for Completion

Part 4-2: Appendix to Bid

Time for Completion, Vol. I

1,092 days

Please refer to Schedule VI: Work Programme for Bid, and to the present Schedule VIII: Method

Statement Section 1.4 Description of Critical Path Works.

We have prepared our Work Programme by giving priority to the requirements of Vol. III: Technical

Specifications in order to achieve the required quality of the Works.

In these Technical Specifications, there are many requirements of Waiting Periods after the

completion of certain works such as:

a. 1 to 3 months after Gravel Compaction Pile (GCP)

b. More than 1 month for preload

c. More than 6 months in principle for consolidation settlement by surcharge.

Some of the above works are carried out in the same area, which means overlapping of these




respective waiting periods. In addition, the site handover periods and all other technical requirements

of each work item as described in our Method Statement are taken into account in the preparation of

the Work Programme.

As a result, Type-H soft ground treatment shall be adopted instead of soft ground treatment by

Additional Gravel Compaction Pile where designated box culvert, abutment and retaining wall in

order to avoid above mentioned waiting period and achieves the completion time within 1,092 days.

Therefore, our Construction schedule is programmed adopting Type-H treatment but not Additional

Gravel Compaction.

1.1.2 TEMPORARY ACCESS ROADS

Location in Contract

Document

Presently Requested Changes

Construction Drawings As per right of way (ROW) As per Schedule VIII: Method

Statement Section 2.3.1

The temporary access roads areas given by the Employer as specified in the drawings at some areas

are too narrow to allow traffic by heavy construction equipment, namely at the areas of construction

of overpass bridges and box culverts.

In such places, the Contractor needs additional widths and areas to carry out temporary road

construction, otherwise it will be physically impossible to carry out the work. Please refer to the

examples in the drawings of this Method Statement Section 2.3.1 Temporary works.

1.1.3 ADDITIONAL POINTS TO BE EMPHASIZED

The following points are clearly set forth in the Contract Documents provided by the Employer.

However, these items have great impact on the Work Programme and the proper delivery of the

Works. Thus, we would like to highlight them here to emphasize our understanding and reach a

mutual agreement with the Employer on them.

The Work Programme was compiled based on our understanding of these items as necessary and

indispensable prerequisites to enable us to adhere to the construction schedule.

Emphasis Point 1: Handing-over of site dates




In reference to Part 4-2: Appendix to Bid Time for granting possession of site, Vol. I: Instructions to

Bidders, which was amended by the Addendum dated 21st February 2011 and received by us on 22

nd

February 2011 (the Addendum), the schedule for handing-over of the Site to Taisei has been

determined as follows:

(a) first section (13+000 14+120 and 15+060 17+500):

7 days after Date of Commencement

(b) Second section (10+500 13+000 and 14+120 15+060):

3 months after Date of Commencement

(c) Third section (A1 Bypass and 8+648 10+500):

6 months after Date of Commencement

This handing-over schedule is critical for us in order to achieve the construction period of 36 months.

Thus, if there is any delay in handing-over the Site in accordance with this schedule, the Engineer

must determine the necessary extension of time for completion of the Works (EOT) and adjustment

of the Contract Price.

In reference to Conditions of Contract Sub-Clause 42.1: Possession of Site and Access Thereto, it

is necessary to reiterate here that the Employers duties are not limited to merely serving notice to

vacate upon owners and user of lands within the right of way of the Contract Works. The Sub-Clause

likewise contains the following necessary implications:

- The construction sites shall be provided to the Contractor by the Employer at the specified time

after commencement for each section.

- The construction site provided to the Contractor shall not be occupied by any remaining residents ,

squatters, etc., so that the Contractor can commence construction activities without annoyance

due to existence of third parties or their property.

Emphasis Point 2: Preliminary survey & soil investigation dates

Our Work Programme is based on the dates of possession of site set forth in the three-step site

handing-over process described above.

Moreover, and as per the Employer Clarification No.02 (page 4 Item 9, and page 6 Item 18), we wish

to reiterate the Employers commitment that preliminary works such as survey, soil investigation,

utilities investigation, etc. can be executed without hindrances prior to the possession of the site.

The dates of these preliminary investigation works are indicated in our Work Programme and the




present Method Statement is based on these dates. Any delay of these dates due to non-fulfillment by

the Employer of the above commitment shall have an effect on the Schedule and as such shall entitle

us to an extension of time and additional cost.

Emphasis Point 3: Utilities diversion under provisional sum

We confirm that no specific subcontractor has been nominated by the Employer in the Permanent

Diversion of Existing Utility or Service in Provisional Sums. Considering the overall construction

schedule requirements, we have fixed the starting dates of these diversion works as shown in our

Work Programme.

Therefore, the Engineers instruction on the Provisional Sum necessary to start diversion work is

essential prior to the starting dates shown in our Work Programme.

We also reiterate here the clear provisions of 1002.1 Delays Caused by Utility Agencies, Section

1000: Provisional Sums, Vol. III: Technical Specifications, namely, if the Contractor has exerted

due-diligence, but delays occur due to these relevant agencies, the Contractor is entitled to EOT and

relevant costs.

Emphasis Point 4: Change of highway lane size from 4-lane to 6-lane

In reference to Conditions of Contract Sub-Clause 52.3: Variation Exceeding 25 percent, we

would like to highlight the following text:

It (Sub-Clause 52.3) shall not apply where the difference in quantities is the result of a Variation

specifically ordered by the Engineer. The provisions of this Sub-Clause shall also not apply to items

of work where Detailed Designs have to be done by the Contractor

The current Drawings and Quantities, and Scope of Works provided by the Employer are based on a

4-lane highway. It is stated in 2. Location and Objectives, Part 3: Scope of Works, Vol. I:

Instructions to Bidders, that future expansion into a 6-lane highway is planned.

We wish to highlight here that such future expansion, if realized, will not be subject to Sub-Clause

52.3 because such expansion will be:

- a variation exceeding 25 percent specifically ordered by the Engineer, and

- a requirement that the Contractor perform Detailed Design (D/D) of the structures.

Therefore, it is clear from the Employers conditions that an expansion to a 6-lane road shall not be

considered an increased volume of works, but shall be implemented under a separate contract

different and distinct from the current one. The Work Programme and all Method Statements

presented here shall not be applicable to any such expansion and there shall be no implication that the




Contractor can or will execute such expansion in accordance with the present project time frame and

costs.

1.2 PROJECT DESCRIPTION

1.2.1 INTRODUCTION

The most important point in the execution and completion of the Greater Colombo Urban Transport

Development Project, Outer Circular Highway to the City of Colombo Northern Section-1 is to plan,

carry out and complete the work safely and to quality standards in accordance with the requirements

given in the Drawings, Specifications and the Terms and Conditions of the Contract, to the full

satisfaction of the Employer and the Engineer. In order to achieve the above objectives, sufficient

coordination with the Employer and the Engineer should be maintained throughout the project period.

We, Taisei Corporation, have a thorough knowledge of highway construction. This knowledge has

been acquired through our former experience in the execution and completion of various highways

not only in Japan, but also overseas. Based on our thorough experience, we emphasize our ability to

safely complete the Greater Colombo Urban Transport Development Project, Outer Circular Highway

to the City of Colombo Northern Section-1 by keeping close coordination with the Employer and

the Engineer.

The Project consists of the construction of the Outer Circular Highway (hereafter OCH) to the City of

Colombo Project, Northern Section-l, from Kadawatha (Sta.8+648) to Kaduwela (Sta.17+500), with

length L=8.9km (break: 17m).

The construction and consulting service costs are funded by Japan International Cooperation Agency

(JICA), Special Terms for Economic Partnership (STEP).

1.2.2 LOCATION AND OBJECTIVES

The OCH is a new full access-controlled circular highway, linking the Colombo-Katunayake

Expressway (CKE) and the Southern Transport Development Project (STDP). It is located 10-15km

from the City center and is 28.89km in total length (Southern and Northern Sections together). It will

connect north and south more quickly as a bypass and disperse traffic from/to Colombo more

effectively, resulting in easing traffic congestion in the Colombo Metropolitan Region.

The OCH will serve a traffic volume of about 25,000 vehicles/day in 2012 with a 4-lane (each 3.5m

wide) highway with a design speed of 80 km/hour.

1.2.3 MAJOR FEATURES OF NORTHERN SECTION-1




Northern Section-l is the second construction section of the OCH, following the first Southern Section,

to connect the Southern Section with the Colombo-Kandy Road (A1 Interchange). It consists of new

construction of an access-controlled 4-lane (each lane is 3.5m wide) highway, with length L=8.9km.

Major quantities are estimated as follows:

Materials from quarries 203(8) 138,340cu.m

Materials from borrow pit 203(7)+203(7)-a 39,610cu.m

Disposal of unsuitable material 203(3) 138,340cu.m

Total material 316,290cu.m

Major soft ground treatment Gravel Compaction Pile (GCP), dia. 700mm

Interchange 2 nos.

- A1 (Kadawatha)

- Kaduwela

Pavement:

Asphalt wearing and binder courses & aggregate road base and sub-base courses

Overpass bridge (PC I-girder) 5 nos. (Total 226m)

- Overpass Bridge No.8 (OB 08) Sta.9+415



- Overpass Bridge No.11 (OB 11) Sta.12+518.921


Incidental works:

Guard rails, road signs, markings, lighting, traffic signals, landscaping, etc.

Utility relocations:

Pylons, electric, telephone and water lines

Conceptual designs for the following permanent works are provided by the Employer. We, Taisei

Corporation, will carry out the Detailed Design (D/D) and construct these structures:

Bridges and viaducts, including interchange ramps: (Total 4,491m)

At Al Interchange

- Main line: Viaduct No.1 (V1) 1 no. PC I-girder 322m

- Ramp (V5-V8) 4 nos. PC I-girder 505m

Ramp-2 Bridge: Viaduct No.5 (V5)




At Biyagama

- Main line (V2-V3,V14&V15) 3 nos. PC I-girder 2,730m




1st Biyagama Viaduct: Viaduct No.2 (V2)

2nd Biyagama Viaduct: Viaduct No.3 (V3)

Viaduct No.4 (V4)

At Kaduwela Interchange

- Kelani River bridges

Main Bridge (HB9) 1 no. PC I-girder 383m

Access Bridge 1 & 2 (Both sides) 2 nos. PC I-girder 427m

- B214 ramp (V9 & V10) 2 nos. PC I-girder 376m

Ramp 1: Viaduct No.9 (V9)


- AB10 ramp (V12 & V13) 2 nos. PC I-girder 401m



- Main line: Viaduct No.11 (V4,V11) 1 no. PC I-girder 1,307m

Total: 17 nos.

1.2.4 CONSTRUCTION SCHEDULE

As indicated in Part 1, Section 1.1.1 Work Programme of this Method Statement, the construction

period of 36 (thirty-six) calendar months specified by the Employer is very tight and challenging.

Thus, we must carefully consider the construction method.

1.2.4.1 GENERAL

Taisei Corporation has completed various projects with similar complexity and work details all over

the world. The minimum construction schedule is 36 months. We have established this schedule based

on a firm and feasible construction method made through proactive studies carried out prior to

commencement of the Works. Therefore, we have spent maximum effort to establish a Method

Statement that we believe is the most appropriate for the Project.

We believe that the following three items are key factors for this project in regard with maintaining

the construction schedule:

Preparing and maintaining firm and stable working formation, i.e., equipment platform, on soft

ground.

Timely implementation of preliminary works, i.e., contractors design and utility relocations.

Implementation of embankment works at appropriate execution speed.

1.2.4.2 PREPARING AND MAINTAINING FIRM AND STABLE WORKING FORMATION




The most important key issue in this project is handling soft ground. This is soft ground consisting of

thick sedimentation of peat layers, especially at viaduct construction areas. However, employment of

large size cranes is inevitable for cast-in-place piling work and girder installation. Therefore, it is very

important for schedule control to consider not only permanent highway structures that are built based

on the Contract requirements, but also construction of crane working formations (platform) and

temporary access roads on soft ground.

We recognize that timely construction of stable working formations and temporary access roads can

lead to the timely execution of the permanent works. On the other hand, if the working formations and

temporary access roads cannot be executed on time or factors such as large displacement during

heavy equipment maneuvering due to poor engineering background study, the total construction

schedule and the safety of the work will be highly jeopardized.

We have acquired a thorough knowledge of handling soft ground and working formations

development and temporary access roads construction during our still ongoing project in western Sri

Lanka (Southern Transport Development Project, STDP Package 2). We have studied various

technical issues, construction methods, etc. enriched by this experience during the tender stage.

Regarding viaduct construction, we have planned our working formation and temporary access road

as indicated below:

Fig. 1.2.4.2.1 Example of a plan of working formation around bridge piers

The access road is set longitudinally beside bridge footings. The width of the access road is 10m so

that two pieces of heavy equipment can pass each other. It is necessary to reinforce the soft ground by




placement of gravel and geo-textile sheet for development of working formation. This working

formation built in accordance with the above reinforcing measures can be set to the side away from

the footing area in the places where it might disturb the piling and excavation works.

Regarding the reinforcement of soft ground for temporary access road only, we are highly doubtful of

the simplified method of replacement of the soft ground with good material. This method will make it

difficult to understand the replaced volume as well as maintain the stability and control the schedule.

Furthermore, there is another concern regarding embankment work, i.e., the occurrence of circular

failure. A typical section of the working formation is indicated in Fig. 1.2.4.2.2.

Fig. 1.2.4.2.2 Typical section of working formation

Placement of geotextile sheet is provided first. This is inevitable to maintain the trafficability of heavy

equipment to be used for working formation construction. Then, the material is spread out in such a

way as to maintain stability against settlement. Another geotextile sheet with sufficient strength

against circular failure is placed on the material. Finally, additional material is placed to form the

formation body. The working formation is built in this way.

Temporary access roads are also built fundamentally the same way. Load of large cranes on soft

ground often creates circular failure and causes various problems in schedule control and safety. This

issue can be avoided by the abovementioned geotextile placement. Surface of access roads will be

kept 1.5m above natural ground in order to prevent inundation of the road during normal flooding and

to shorten non-working period to minimum. This working formation development plan will be

verified through trial execution. Based on results derived through trial execution, the firm

development method will be fixed, we believe this will contribute to the success of our schedule

management.

1.2.4.3 TIMELY IMPLEMENTATION OF PRELIMINARY WORKS

Assumed circular failure line to be prevented

0.3-0.5m

Vary 0-3.5m

Peat stratum

0.5-2.0m

Geotextile sheet where necessary

Geotextile where necessary for

prevention of circular failure

Replaced material (Soil)

Gravel (Crusher run)

Soil

150t CC

Boulders where necessary

(Top elevation depend flood water level)




a. General

Regarding bridge construction, nothing is as important as commencing the construction works as soon

as possible. This applies for both substructures and superstructures. Detailed designing of bridges and

execution of utility relocations are two important items to be completed before commencement of

bridge works. We are going to concentrate the design works at the early stage in order to obtain the

Engineers approval.

b. Design schedule

We have acquired a thorough knowledge of how to smoothly obtain design approval through our

ongoing project in western Sri Lanka, i.e., Southern Transport Development Project, STDP Package 2.

We will submit the Detailed Design (D/D) separately in regard to portions of the works instead of

submitting a whole design at once. This is to reduce the workload of the Engineer and at the same

time shorten each approval period. Thus, design submission will be held on portion-to-portion basis,

such as for piling, substructure, superstructure, etc. Eventually, we expect that the Engineers

approval will be issued for each portion separately.

We consider that it will take 7 (seven) days to get the Engineers comments on the Contractors initial

submission, another 7 (seven) days will be required to modify and resubmit the design based on the

Engineers comments and additional 7 (seven) days are needed to acquire the final approval of the

design by the Engineer. Eventually, we consider that it will take a total of 21 (twenty-one) days from

initial submission to obtain the Engineers approval of the Detailed Design (D/D) for each portion.

Once the Engineers approval for the Detailed Design (D/D) of a certain portion is acquired, we will

commence the construction of that portion immediately.

c. Utility relocations

Another key factor affecting early start of construction is utility relocations. We fully recognize the

importance of utilities as a lifeline of local residents. Therefore, we are going to employ robust and

stable structures such as a culvert foundation of water line indicated on the Tender drawing for

relocation works, and we will pay our utmost effort to minimize the interruption periods during

relocation activities for the sake of eliminating long blackout, water cut-off, etc.

Investigation of underground utilities will be basically carried out along the supposed locations

indicated on drawings. If unknown underground utility is found at locations other than previously

indicated prior to or during the work execution, the work shall be stopped immediately, and the

incident shall be reported to the Engineer and relevant authority, and temporary emergency treatment

will be provided to the utility found. Then, the Contractor will carry out planning and diversion design,

if applicable, together with the relevant authority. The work will be restarted following the Engineers

approval of the plan. The total cost incurred for such unknown utility shall be paid to the Contractor

under Provisional Sum as replied in item No.16, Clarification No.02.




We have considered sufficient time frame of utility diversion as indicated in our Work Programme

including discussion period with relevant authorities and the authorities working period. Nevertheless,

if diversion work cannot be completed within the specified period, the Contractor shall be reimbursed

additional cost in addition to EOT specified in 1002.1 General, Section 1000: Provisional Sum, Vol.

III: Technical Specifications.

1.2.4.4 IMPLEMENTATION OF EMBANKMENT WORKS IN APPROPRIATE EXECUTION

SPEED

As for embankment execution, too slow execution will delay the progress while quick execution

might cause circular failure and finally deteriorate the quality of the work and delay the progress.

Therefore, it is important to carry out the work in a timely manner, with appropriate execution speed,

neither slow nor quick, for maintaining the quality and construction schedule.

It is quite important to properly predict future settlements before paving work for the sake of

eliminating various deteriorations caused by settlement such as cracks on pavement. We have studied

thoroughly regarding the relations between planned embankment execution speed and stability of the

embankment and also between planned speed and future settlement amount. We have acquired a

thorough knowledge of these phenomena through ongoing project in western Sri Lanka (Southern

Transport Development Project, STDP Package 2). Thus, we are fully confident in our current plan.

We believe that additional soil investigation to be carried out after award of the project will enforce

the preciseness of our plan and the feedback from actual monitoring results during execution can

significantly contribute to both construction schedule control and quality control.

1.2.5 ENVIRONMENTAL MANAGEMENT PLAN (EMP)

The Northern Section-1 is located mostly in marsh and abandoned paddy fields. We will pay

sufficient attention not to produce any air and water pollution, noise and vibration during the

construction. At the same time, we will keep good relations with neighbouring residents, including the

convenience of access and temporary roads.

In the whole process regarding environment, Taisei Corporation will follow the Environmental

Management Plan (EMP) in the Tender documents, as well as the various regulations and instructions

included in the Central Environmental Agencys (CEA) approval letter (included in Data provided by

the Employer).

It is our fundamental desire to maintain the splendid atmosphere of the outer suburb of Colombo and

to limit the effects of highway construction on the environment to a minimum. We have decided not




to change any routes of natural brooks or streams from their original locations. Thus, we are going to

install pipes not only in the permanent structures but also in our temporary access roads.

In addition to the abovementioned countermeasures for flood, we plan to install temporary staging as

shown in Fig. 1.2.5.1. This staging will be applied specifically at viaduct areas, because the geological

condition of these areas is very weak and many heavy types of equipment, such as 150t cranes have to

pass continuously for piling work and superstructure work. Location and number of these bridges

should be decided as per the actual site condition.




Fig. 1.2.5.1 Example of temporary staging for flood




We are concerned about the low potential of hydrogen, PH4, of peat strata found in some area.

Exposed peat will cause unfavorable odor to surroundings and might be a cause of future water

contamination.

We would like to discuss with the Engineer regarding this matter after the Contract award. One of the

countermeasures considered is to dispose the peat into hollows derived from brick clay mining

existing here and there and cover them by topsoil (refer to Fig. 1.2.5.2). It will not only solve the

issues of the low potential of hydrogen, but also eliminate water pools after rain that bring incidence

of mosquitoes and epidemics.

Hollow derived from brick clay miningTopsoil

Disposed peat

Topsoil

Fig. 1.2.5.2 Disposal of peat into hollow and covering it by topsoil

1.2.6 SAFETY AND PUBLIC RELATIONS

We believe that all accidents can be avoided if appropriate procedure is taken by suitable workforce

with sufficient safety consciousness and well maintained proper equipment. Soon after receiving the

Contract award, we will establish a Safety manual specific to this project. All construction activities

shall strictly follow this manual. Some of the key elements we are going to employ include the

following:

1. Daily risk assessment meeting

2. Safety training provided for all personnel involved




3. Establishment of safety management with daily, weekly and monthly routine cycles

4. Establishment of monthly safety awarding system

5. Enforcing strict safety rules for preventing accidents by equipment, falling, etc.

6. Providing sufficient number of warning signs or keep off signs for dangerous areas, clear

indication of temporary access roads, etc.

7. Providing periodic safety patrol by staff of Safety department and Engineering department of

International Operations Headquarters

8. Establishment of strict safety rules for blasting, if applicable, such as specified protective

measures or fixing the evacuation distance

9. Providing various measures to avoid accident involving a third party, such as employing traffic

controller at all intersections of temporary access roads with public roads

10. Explanation to adjacent residents including key persons of the region regarding danger in the

construction site

11. Establishment of an honest compensation system in case of an accident

12. Providing sufficient safety protection goods including helmet, safety shoes, safety jackets, etc. for

all workforce involved

13. Provision of strict safety training for newcomers

14. Establishment of a monthly safety meeting. Workers shall point out hidden factors of accident to

each other. Thus, self-safety consciousness is increased.

15. Occasional safety patrol by owners of specific Subcontractors

16. Routine checking of staging and scaffolding around structures

We believe it is very important to acquire local residents supporting attitude toward the Project. We

plan to support the Employer through the development and implementation of public relations. Based

on approval by the Engineer, we will have occasional meetings with local residents to explain the

intent and meaning of the Project together with construction activities carried out for the sake of

avoiding accidents involving a third party.




1.3 PROCESS CONDITIONS

1.3.1 WORKABLE DAYS

In order to determine the operation rate of the Project, weather conditions, holidays in Sri Lanka and

type of work are taken into account for the site location.

1.3.1.1 WORKING CONDITIONS BASED ON TYPE OF WORK AND PRECIPITATION

Precipitation data at the Homagama Station were investigated for a 10-year period, from 1999 to 2009.

Since especially recent precipitation is stronger than earlier one, we use recent data of the last 5 years

(2005 2009) in the analysis of operating rate (see Table 1.3.1.3.1).

Daily precipitation (p) data are grouped into 4 (four) categories, while main works of the Project are

classified into 3 (three) types, as shown in Table 1.3.1.1.1. From our past experience we consider the

number of days lost and the status of operation based on precipitation p for each type of work as

follows:

Table 1.3.1.1.1 Working conditions based on type of work and precipitation (p)

Rainfall

(mm/day)

Type of work

Work loss (day)

p1.0 1.0




Table 1.3.1.3.1 Workable days and operating rate

Month Remarks

Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec Annual

Days 31 28 31 30 31 30 31 31 30 31 30 31 365

Rest days 8 7 5 8 7 5 6 5 5 8 5 8 77

Workable days (day/month) considering unworkable days due to rain only Average

Earthworks/

Paving works 23 24 22 15 15 15 22 19 16 10 8 22 17.3

Piling works/

Other works 28 27 28 25 26 25 28 27 25 23 21 28 25.5

Operating rate (%) considering unworkable days due to rain only Annual

Earthworks/

Paving works 73% 85% 70% 50% 49% 50% 70% 61% 54% 34% 28% 71% 58%

Piling works/

Other works 90% 95% 90% 82% 83% 83% 91% 86% 84% 73% 71% 90% 85%

Workable days (day/month) considering unworkable days due to rain & rest days*1) Average

Earthworks/

Paving works 17 18 18 11 12 12 17 16 13 8 7 16 13.6

Piling works/

Other works 21 20 23 18 20 21 23 22 21 17 18 21 20.1

Operating rate (%) considering unworkable days due to rain & rest days*1) Annual

Earthworks/

Paving works 54% 64% 58% 37% 38% 41% 56% 51% 45% 25% 23% 53% 46%

Piling works/

Other works 67% 71% 75% 60% 64% 69% 73% 72% 70% 54% 59% 67% 67%

Modified operating rate (%) applied in planning

Unworkable days/

month (due to rain)

Rest days/month

(non-rainy days)

Unworkable days/

month (total)

Workable

days/month Annual

Earthworks/

Paving works 14.3 3.7 18.0 12.0 40%*

2)

Piling works 4.6 2.9 7.5 22.5 75%*3)

Other works 4.6 4.4 9.0 21.0 70%*4)

*1)

Some rest days are also rainy days; therefore the number of rest days is reduced

*2)

Modified operating rate is based on our ongoing experience in Sri Lanka: 46% is reduced to 40%

*3)

Half of rest days are considered as working days: (85%+67%)/2

*4)

One rest day is considered as working day to ensure the planned construction schedule: +3%




1.3.2 MATERIAL CONVERSION FACTORS

In our estimation and planning, we employed the material conversion factors in Table 1.3.2.1:

Table 1.3.2.1 Material conversion factors

Material Original condition Converted condition

Ground Loosened Compacted

Soil

Classified material

Borrowed material

Ground 1.00 1.20 0.93

Unsuitable material Ground 1.00 1.25 0.90

Soft rock

(Excavation) Ground 1.00 1.30 1.15

Hard rock

(Excavation) Ground 1.00 1.60 1.25

Quarry material Ground 1.00 1.65 1.40

1.3.3 PRODUCTION RATES

All production rates prepared by Taisei Corporation are based on our assumptions; therefore actual

production rate values may differ from those indicated in the followings.




1.3.3.1 EARTHWORKS

Table 1.3.3.1.1 Production rates for earthworks

Type of work Detail Equipment Productivity

( /dayno)

Excavation

Classified material for reuse Backhoe 0.9cu.m class

Bulldozer 15.85t class 425 cu.m

Hard rock material for reuse

Bulldozer 41.2t class with

Ripper

Crawler drill (hydraulic)

150kg class

80 cu.m

Unsuitable material Backhoe 0.8cu.m class 200 cu.m

Fill

Roadbed of embankment Bulldozer 15.85t class

Vibratory roller 12.5t class 400 cu.m

Soft soil excavation

(using quarry material)

Bulldozer 43.2t class


Slope formation Cut slope Backhoe 0.4cu.m class 160 sq.m

Fill slope Backhoe 0.4cu.m class 120 sq.m

Subgrade

Grading Grader 3.7m class 3,300 sq.m

Spreading & compaction Bulldozer 15.85t class

Tire roller 8-15t class 1,500 sq.m

Band drains Pile driver for band drain 1,700 m

Gravel mat Gravel size: max. 50mm

Spreading & compaction

Bulldozer 15.85t class


Compacted general

fill Gravel size: max. 50mm

Crawler type pile driver

50t class 210 m

1.3.3.2 PAVING WORKS

Table 1.3.3.2.1 Production rates for paving works

Type of work Detail Equipment Productivity

( /dayno)

Subbase

Motor grader 3.1m class

(with Vibratory roller 8t class &

Tire roller 8-15t class)

3,600 sq.m

Aggregate road base

Asphalt paver

(with Vibratory roller 8t class &


3,000 sq.m




Asphalt concrete

binder course

Asphalt paver 2.5-6.0m class

(with Macadam roller &


600 tonne

Asphalt concrete

wearing course

Asphalt paver 2.5-6.0m class

(with Macadam roller &


600 tonne

Portland cement

concrete pavement

Slipform paver 2.0-6.0m class 500 sq.m

1.3.3.3 BRIDGEWORKS

Table 1.3.3.3.1 Production rates for structural works

Type of work Detail Equipment Productivity ( /day)

Common excavation Backhoe 0.7cu.m class 210 cu.m

Soft rock excavation Backhoe 0.7cu.m class

+ Hydraulic breaker 30 cu.m

Bored pile *2)

Both RCD and AC piling methods

Reverse Circulation Method (RCD)

All Casing Method (AC)

Earth Drilling Method (ED)

6.5

0.250

0.250

165.0

m/h soil

m/h rock *1)

m/h rock *1)

m/13h

Rebar Base slab Track crane 25t class 2.0 tonne

Wall/Column Track crane 25t class 2.5 tonne

Formwork

(Installation &

dismantling)

Base slab Track crane 25t class 30 sq.m

Wall/Column Track crane 25t class 25 sq.m

Concrete placing

Base slab/

Wall/Column Concrete pump 90110cu.m/hr 300 cu.m (max)

I-girder Pump, bucket & crane 85 cu.m (max)

PC I-girder installation Crane erection Crawler crane 150t class x 2 4 nr.

*1)

We estimate rock unconfined compressive strength 50MPa based on the Tender document.

*2)

Productivity of bored pile is the drilling speed.




1.4 DESCRIPTION OF CRITICAL PATH WORKS

Refer to the submitted Work Programme for details regarding the construction schedule. Critical path

activities are given in sequence, for clarity.

We prepared the Work Programme in which the whole Work will be completed within 36 (thirty-six)

months, based on bidding documents such as drawings, including Topographic Survey Data,

Technical Specifications, Data Provided by the Employer, etc.

In addition, major assumptions to the Soft Ground Treatment Type-A to G area that the Work

Programme is based on completion within 36 months are as follows:

1. The Contractors possession of the Site is implemented in three steps, i.e., within 7 days after the

Date of Commencement, exactly 3 calendar months from the Date of Commencement and exactly

6 calendar months from the Date of Commencement. The last point in each time frame is

employed (Page 27, Part 4-2: Appendix to Bid, Vol. I: Instructions to Bidders & Addendum

No.02).

2. Stabilizing leaving period after the GCP execution is fixed to 1 calendar month. The earliest point

of the time frame is employed (Page 33 of 50, 3.3 Gravel Mat and Gravel Compaction Pile,

Section 204: Soft Ground Treatment, Vol. III: Technical Specifications).

3. Preloading leaving period is fixed to 1 calendar month. The earliest point of the time frame is

employed (Page 33 of 50, 3.3 Gravel Mat and Gravel Compaction Pile, Section 204: Soft Ground

Treatment, Vol. III: Technical Specifications).

4. Surcharge leaving period is fixed to 6 calendar months. The earliest point of the time frame is

employed (Page 36 of 50, 3.6 Surcharge, Section 204: Soft Ground Treatment, Vol. III: Technical

Specifications).

Critical path works in our 36-month Work Programme are indicated in Table 1.4.1 and Fig. 1.4.1.

This Work Programme and these critical path works are based on the above assumptions.

Thus, it should be emphasized that the Programme and the critical path may differ depending upon

any changes in the above-mentioned assumptions 1 through 4 (such as extended preloading and

surcharge leaving periods), additional ground investigation and boring data, soft ground treatment

testing and site survey, etc.




Table 1.4.1 Critical path activities for the Project based on 36-month schedule

Critical path activities for the Project (1)

No.Activity

ID*Section Task

Duration of task

(day)

Critical duration

(day)Remarks

1 3 KEY DATE COMMENCEMENT 0 0

2 62 Instruction for Diversion of Existing Utilities by the Engineer 0 0

3 68 Planning of Diversion of Existing Utilities for Section 3,4,5 & 6 79 79

4 64 Planning of Diversion of Existing Utilities for Section 1 & 2 78 78

5 65 Discussion and Approval from the Authorities concerned 14 14

6 66 Discussion and Approval by the Engineer 14 14

7 166 Diversion of Existing Utility 90 90

8 168 Clearing & Grubbing 30 30

9 187 Gravel Mat 120 60 Overlapping with ID No. 189

10 189 Compacted General Fill 60 60

11 185 Geotextile 125 95 Overlapping with ID No. 188

12 186 Band drain 125 95 Overlapping with ID No. 188

13 188 Gravel Compaction Pile 700 (Incl. Leaving period of One Month) 125 95

14 178 Fill for Road-bed of Embankment @ SGT Area 270 270

15 180 Surcharge Duration(incl. Engineer's approval) 255 215

16 183 Subgrade with Selected Material or Capping Layer 332 30

17 192 Sub-base Course for Flexible Pavement 340 22

18 194 Aggregate Road Base 340 9

19 195 Prime Coat 210 15

20 197 Asphalt Concrete Binder Course 210 15

21 196 Tack Coat 210 15

22 198 Asphalt Concrete Wearing Course 210 15

23 284 INCIDENTAL WORK 240 30

24 285 FACILITY WORK 240 30 Parallel with ID No. 284

25 4 KEY DATE COMPLETION 0 0

3,107 1,096

* Refer to Schedule VI: Work Programme for Bid

Total

SECTION 2

(Sta.8+970-

Sta.10+500)

GENERAL

Critical path activities for the Project (2)

No.Activity

ID*Section Task

Duration of task

(day)

Critical duration

(day)Remarks

1 3 KEY DATE COMMENCEMENT 0 0

2 40 Instruction for Additional Soil Investigation 0 0

3 41 Planning of Additional Soil Investigation 30 30

4 42 Discussion & Approval by the Engineer 21 21

5 50 Additional Soil Investigation for Structure (HB9,V4 & Ramp) 70 70

6 472 Detailed Design of Concrete Bridge 150 42

7 473 Approval by the Engineer 21 21

8 534 Test Pile 100 100 Parallel with ID No. 557

9 557 Bored Piling 100 100

10 558 Excavation (incl. Temporary Shoring) 180 120

11 559 Substructure 180 30



14 544 Excavation (incl. Temporary Shoring) 60 60


16 546 Girder Erection 29 29

17 553 Girder Erection 28 28

18 547 Deck Slab 30 30

19 554 Deck Slab 30 30

20 548 Waterproof/Pavement 90 90 Parallel with ID No. 555

21 555 Waterproof/Pavement 90 90

22 467 Tack Coat 150 60

23 469 Asphalt Concrete Wearing Course 150 5

24 604 INCIDENTAL WORK 207 30

25 605 FACILITY WORK 207 30 Parallel with ID No. 604

26 4 KEY DATE COMPLETION 0 0

1,904 1,096

* Refer to Schedule VI: Work Programme for Bid

Total

SECTION 6

(STA.15+060~ST

A.17+500)

1.GENERAL




Fig. 1.3.3 Work Programme Critical Path Activities




1.5 PARTICULAR CONCERNS

1.5.1 HANDOVER PROCEDURE

Upon substantial completion of any part or section of permanent works, we, Taisei Corporation will

arrange the necessary requirement for the handing over procedure. At any time such part or section of

the Works has passed all tests and has been satisfactorily accepted by the Engineer, authorized

representatives of both parties will duly certify the Joint inspection sheet.

The Project manager will manage his subordinates and deal directly with the Engineer to conduct a

joint inspection for any part or section of the Works which had been substantially completed, on the

agreed date and in the presence of the Engineers representative. The joint inspection will consist of:

1. Specific testing method

2. Commissioning test

3. Defects inspection

4. Maintenance regimes

5. Provision of spares

6. And any other test(s) required under the conditions stipulated in the Contract.

The Project manager is responsible for the handing over procedure, for which it is necessary to:

1. Prepare the format of Joint inspection sheet

2. Prepare punch list and notice of his intention to conduct the test or inspection on a specific date

and time

3. Carry out the test or inspection for handing over on the date agreed and in the presence of the

Engineer

4. Forward to the Engineer duly certified copies of the Joint inspection sheet

5. Formally request the Engineer to issue the Taking-over certificate, stating the date when the

Works become substantially completed.

The flowchart for handing over procedure is shown in Fig. 1.5.1.1 for further reference.




Engineer Taisei Corp.

Fig. 1.5.1.1 Handover procedure

Cleaning

Repair,

remedy

Inspection

Inspection

Inspection

Repair,

remedy

Yes

No

Punch list

Application

No

Yes

Handing over

Approval

Application

Issuance of

Taking-over

Certificate




1.5.2 DEFECTS LIABILITIES

We will establish a firm organization during the defect liability period of 365 (three hundred and

sixty-five) days to carry out any remedial works, which may arise in this period and also such

outstanding items of the Works as are listed in the Taking-over certificate. This organization for the

defect liability period consists of senior engineers for civil works, mechanical works, electrical works

and quality assurance.

The assignment of each senior engineer will be discussed with the Employer and the Engineer in

order to be approved. The role and responsibilities of these engineers are as follows:

1. To take overall quality management and coordination of remedying works; and

2. To be responsible for any defect item regarding civil, mechanical and electrical works.

If any defect item is found by us or informed by the Employer, the item will be investigated by the

Quality engineer, and be categorized into each work scheme. The senior engineer in charge of the

work scheme is assigned to remedy the defects and outstanding items. He will immediately contact

his staff and the Subcontractor and let them perform the remedy work to the satisfaction of the

Employer and the Engineer.

The flowchart of remedy work during the defect liability period is shown in Fig. 1.5.2.1:




Engineer Taisei Corp.

Fig. 1.5.2.1 Remedy work during the defect liability period

Notice

Inspection

Person in

charge

Report

to

Head

Office

Inspection

Method

Inspection

Issuance of

Defect Liability

Certificate

Repair,

remedy

Completion

Yes

No

Yes

Request for

Defect Liability

Certificate

Approval

Approved

method of repair

Application for inspection




2. PART 2:

CONSTRUCTION METHODS WITH CONSTRUCTION

RESOURCES

2.1 GENERAL

We, Taisei Corporation, believe that it is our duty to complete the Works conforming to the relevant

Drawings, Specifications and other requirements described in the Contract documents and to carry out

the Works following any local laws and regulations, paying utmost care for environmental and safety

issues for the sake of obtaining the utmost satisfaction of the Employer and the Engineer.

We would like to execute the Project based on our previous experience in highway construction

projects, both in Japan and overseas and also our experience in project implementation in Sri Lanka.

2.2 OVERALL WORKFLOW

The whole project site is divided into 6 (six) working sections as indicated in Fig. 2.2.1. Major

earthwork material and filling material are directly delivered to the execution site in order to diversify

hauling vehicles and therefore to mitigate traffic jams.

Temporary construction road is provided along the highway alignment. Construction materials such

as concrete or asphalt, heavy equipment, etc. are transported by using this temporary construction

road so as to minimize public roads usage from the point of view of environmental protection.

For the sake of project implementation it is necessary that all works are well coordinated with each

other in a manner satisfactory to the Employer and the Engineer. Construction method of each work

item is described in the followings.




Fig. 2.2.1 Overall project plan

Sta.15+060

Sta.17+500

Sta.13+000

Sta.8+648

SECTION 6

SECTION 5

SECTION 2

V4 & HB9

& V11

V3

V2

OB 08 (Sta.9+415)

OB 10 (Sta.11+261)

OB 11 (Sta.12+518)

OB 12 (Sta.14+843)

Exactly 6 months from the Date

of Commencement

Exacaly 3 months from the

Date of Commencement

Exactly 7 days after the

Notice to Commence

OB 09 (Sta.10+210)

Box Culvert Sta.14+619

B214

AB10

A1

B262

B169

B221

SECTION 1

SECTION 3

Excactly 3 months from the

Date of Commencement

Sta.10+500

SECTION 4

Exactly 7 days after the

Notice to Commence

Exactly 6 months from the Date

of Commencement

Sta.14+120

V1

V14

V15

OCH Northern Section-1 (L=8.9+1.9km) OB = Overpass Bridge Box Culvert V = Viaduct

VIADUCT (L=6.1km)




The Work area is divided into 6 (six) different sections as shown in Fig. 2.2.2. Work at each section

shall start immediately following the site possession. Refer to Section 1.1.3 "Additional points to be

emphasized of this Method Statement for further details.

Temporary site offices and facilities

Temporary access roads

Sec

tion 1

A1 B

yp

ass

Sec

tion 2

(Sta

.8+

648S

ta.1

0+

500)

Sec

tion 3

(Sta

.10+

500S

ta.1

3+

000)

Sec

tion 4

(Sta

.13+

000S

ta.1

4+

120)

Sec

tion 5

(Sta

.14+

120S

ta.1

5+

060)

Sec

tion 6

(Sta

.15+

060

S

ta.1

7+

500)

Exac

tly 6

month

s fr

om

the

Dat

e of

Com

men

cem

ent

Exac

tly 6

month

s fr

om

the

Dat

e of

Com

men

cem

ent

Exac

tly 3

month

s fr

om

the

Dat

e of

Com

men

cem

ent

Wit

hin

7 d

ays

afte

r th

e

Noti

ce t

o C

om

men

ce

Exac

tly 3

month

s fr

om

the

Dat

e of

Com

men

cem

ent

Wit

hin

7 d

ays

afte

r th

e

Noti

ce t

o C

om

men

ce

Fig. 2.2.2 Work division into working sections




For each section, work will be carried out as shown in the flowchart in Fig. 2.2.3.

Fig. 2.2.3 Overall workflow

Preliminaries

Temporary access

road construction

Foundation pile

Substructure

Soft ground treatment procedures

(if required)

Fill for embankment

Clearing and grubbing,

removal of structures,

utility relocation works

Surcharge

(as soft ground

treatment procedure)

Subbase course

and Aggregate road base

Asphalt course

Box culverts

Incidentals and

Facilities

PC I-girder

Slab work, etc.




2.3 COMMON WORK ITEMS

2.3.1 TEMPORARY WORKS

a. Temporary road construction

Temporary construction roads and crane working formations are developed prior to main work

execution in order to haul earth material and provide stable crane operation. These construction roads

and working formations are constructed along the highway alignment. Most of the working

formations and temporary roads are constructed on soft ground. Therefore, firm roads and working

formations are prepared in order to maintain smooth traffic and stability. Width of temporary road is

8m for earthwork area and 10m for viaduct area.

Periodic rectification of uneven surfaces is carried out by using motor grader. Crushed stone is

provided at settled areas if needed. Water sprinkling is provided by using water lorry to prevent dust

pollution. Temporary pipe culvert is provided at river crossing areas. Traffic controllers are assigned

and notice boards, barricade, etc. are provided for intersection with existing roads or diversion roads.

The temporary construction road is to be built along the whole section of the main road. This

temporary construction road shall be a rigid one considering maneuverability and traffic volume of

construction vehicles. The main road alignment is located mainly on marshy areas. Eventually, the

temporary construction road will obstruct natural water flow during flood. Therefore, temporary

drainages and bridges will be provided in embankment areas of the temporary construction roads so

as to allow the floodwater to flow in similar manner to the main road (refer to Fig. 1.2.5.1).

In the Drawings the ROW area given by the Employer is specified, where temporary access roads can

be built. However, this ROW at some areas is too narrow to allow traffic by heavy construction

equipment especially at the areas of construction of overpass bridges and box culverts.

In such places, we will require additional width and areas for the sake of temporary roads construction

otherwise it will be physically impossible to carry out the work. Refer to examples in Fig. 2.3.1.1 and

Fig. 2.3.1.2. Additional drawings for each area of construction of the overpass bridges and box

culverts where the temporary road will exceed ROW shall be provided after contract signing.




Fig. 2.3.1.1 Example of temporary road outside ROW (box culvert)




Fig. 2.3.1.2 Example of temporary road outside ROW (overpass bridge)




b. Diversion road construction

Diversion roads are constructed to maintain traffic on major roads during the execution of the Project.

Dimensions of diversion roads are similar to those of original roads. Temporary land acquisition is

executed in case the diversion road is constructed outside the ROW.

In the case of existing roads being used as diversion roads, required rectification such as widening, etc.

is provided. Traffic controllers are assigned and notice boards, barricade, etc. are provided for the

sake of smooth traffic, and water sprinkling is provided by using water lorry to prevent dust pollution.

2.3.2 UTILITY RELOCATION WORKS

a. General

In the Bidding documents, there are 3 (three) types of utilities: electrical power lines by the Ceylon

Electricity Board (CEB), water supply by the National Water Supply & Drainage Board (NWS & DB)

and telecom line by the Sri Lanka Telecom (SLT). These utility relocation works directly affect the

critical path. Management and coordination with each agency are very important. After having

received from each utility agency instruction to relocate the permanent position, we can start the

actual planning for relocation. Relocation scheme is as follows:

2-step relocation scheme

Step 1 Preparation work for permanent utility relocations (if necessary)

Step 2 Final permanent utility relocations

b. Scope of Work

CEB Overhead Power Transmission Lines:

- Power line of 35kV or more and sub-line systems including pylons

- Intermediate power transmission line of 3kV to 35kV

- Low voltage power distribution line of 400V/230V after transformer substation

- Transformer stations distribution capacity of 500kVA to 1500kVA

- Transformer stations distribution capacity less than 1500kVA

SLT Telephone Lines:

- Overhead line or underground metallic or fiber-optic cables

NWS & DB Underground Water Pipes:

- Water distribution mains and transmission mains

1) Less than 100mm diameter

2) 100 mm to 1000mm diameter

- Water Services

- Property water services 20mm or larger




2.3.3 EXCAVATION, EMBANKMENT AND HAULING WORKS

Earthwork is the major work item of the Project. All earthwork will be executed in accordance with

the relevant Specifications and Drawings. The detailed execution method statement for each

earthwork item will be submitted to the Engineer for approval prior to commencement.

Felling, clearing and grubbing are carried out prior to main earthwork. All topsoil is removed to a

depth of 20cm. Removed topsoil with high water content is dried under the sun and then hauled to

designated dumping site. Backhoe (0.8cu.m class) is used for clearing and grubbing. Felled trees are

stocked at designated locations.

Removal of existing structures takes place. Considering the existing conditions, structures to be

removed are thought to be drainage facilities, pavements, road facilities, buildings, fences, guard rails,

telephone poles, traffic signs, etc. These, depending on the type of objects to be removed, are

demolished and removed by backhoe (0.8cu.m class), with or without breaker. Then, unsuitable waste

material is to be hauled to the designated dumping site, while suitable waste material, e.g. crushed

stone, etc., is used, for example for the embankment of construction roads. After removal of existing

structures, backfilling and leveling of the Site take place.

Excavation and embankment works are carried out following clearing and grubbing, as well as the

removal of existing structures. Common soil is excavated mechanically by using backhoe

(0.8-1.4cu.m class) and/or bulldozer (15-42tonne class), and is transported by dump trucks (8-15tonne

class). As for excavated materials, suitable ones are used for embankment or backfilling, while

unsuitable ones are hauled to the designated dumping site.

In regard to rock excavation, we decided not to use ordinary explosives because of surrounding

circumstances and total volume of rock excavation. We planned to use non-explosive demolition

agent instead of explosives, as this method will not cause big blasting noise. Broken rock mass is

collected by bulldozer (42tonne class), and then loaded onto dump truck (8tonne class) by using

backhoe (1.4cu.m class).

Borrow material conforming to the Specifications is delivered from outside the site. Filling material,

borrow material and excavated suitable materials are transported to the embankment site in order to

be spread uniformly in thin layers (conforming to the Specifications) and compacted. Water content

of filling material is adjusted by water sprinkling, by using water lorry. Excavated rock material is

placed in layers equal to the average rock dimension conforming to the Specifications. Rock

spreading is carried out by using bulldozer (32-42tonne class). During spreading filling material,

specific care is taken so as not to damage the previous compacted layer. Rock layer is compacted by

using vibratory roller (8tonne class).




Throughout the execution of earthworks, the following points are always monitored and checked from

the point of view of quality control:

a. Excavation

Excavated base is not disturbed

Rainwater and other water encountered is always drained thoroughly

Excavated bases are kept as dry as possible

Excavated bases are always smooth and uniform

b. Embankment

Embankment layers is spread to the specified thickness and compacted with appropriate

moisture content to achieve the specified density

The following items will not be allowed to become mixed up with the embankment material:

- Organic matters

- Debris

- Trees, stumps and roots

c. Hauling works

Hauling vehicles strictly follow the local traffic rules and all regulations established by the

Safety division of the site organization

2.3.4 DRAINAGE WORKS

a. River canal relocation at Rakgahawatta

We will relocate the Rakgahawatta Ela as shown in the Drawings (Sta.15+915). This work consists of

excavation/filling and construction of rubble masonry sidewalls in accordance with the levels, sizes

and dimensions given on detail drawings.




b. Pipe culverts

A typical section of pipe culverts and construction sequence with details is given in Fig. 2.3.4.1.

DN

Pipe culvert

Selected backfill material

BD > DN + 2t + 2 x 0.5 m

tt

Fig. 2.3.4.1 Typical section of pipe culverts and construction sequence

Concrete pipes are manufactured according to the Specifications and Drawings. The concrete

pipe manufacturing process is accessible to the Engineer for inspection in order to ensure that the

product meets the required specifications.

Excavation is done by backhoe (0.8cu.m class), which loads the soil on dump truck to be hauled

away. Excavation width is taken as to ensure at least 50 cm from the outer side of each side of

the pipe. Good compaction is done to bedding layer beneath the pipe. After compaction, the level

of bedding is confirmed and reported to the Engineer for approval. The pipe is then installed.

Pipes are inspected just before installation to ensure no damage is present. The Engineers

approval is then requested before installation of the pipe. Installation is done by crane (25tonne

class) with a capacity suitable to the diameter of the installed pipe. For jointing pipes, mortar is

applied on the peripheral section of the previous pipe before installing the following one to

ensure adherence between the two pipes. After jointing pipes, surplus mortar in the inside of pipe

is cleaned. The mortar on the outside of pipe is cured for two days by an appropriate method

before backfilling.

Backfilling material is brought to site on land by dump trucks. It is made sure that no stone with

a size of 25mm or above is present in the backfilling material, and such stone is cleared from

backfilling soil if found before backfilling. Backfilling is done by backhoe (0.8cu.m class), which

mounds the soil while taking care not cause any damage to the pipes. Compaction is done after

each layer of approximately 20cm of backfill.

Excavation and

bedding

Preparation works and

concrete pipe

Pipe culvert

installation

Backfilling




c. Ditches

A typical section of ditches and construction sequence with details is given in Fig. 2.3.4.2.

MortarRiprap stone

Fig. 2.3.4.2 Typical section of ditches and construction sequence

Excavation is done in a similar manner to the excavation for reinforced concrete pipes described

previously. Excavation dimension is equal to the ditch type drainage to be constructed, without any

over-excavation. After compaction, the level of the bedding is confirmed and reported to the Engineer

for his approval.

Wide and flat stones are chosen with their larger faces roughly rectangular and parallel to each

other. Thickness of stone is 30cm (measured perpendicular to the faces of the stone). Front top

face is lined to the required line and grade. All spaces under the stone are filled and tamped with

the same material as the bed course.

Stones are laid with closed joints and filled with mortar as specified. Mortar is composed of one-

part cement and two-part sand by dry loose volume, and suitable amount of water to make a

mortar that can be easily handled and trowelled.

Installation of riprap stone

Excavation and bedding

Filling with mortar




d. Catch basins

Fig. 2.3.4.3 shows a typical section of catch basins and construction sequence with details.

Concrete

Reinforcement

Cover

Fig. 2.3.4.3 Typical section of catch basins and construction sequence

Excavation is done in a similar manner to the excavation for reinforced concrete pipes described

previously. After compaction, the level of bedding is confirmed and reported to the Engineer for

his approval.

Gravel is transported to site on land, by using dump trucks. A backhoe (0.8cu.m class) mounds

and spreads the material. Compaction is done by using compacting machines. After spreading

and compaction, the shape of foundations gravel layer is checked and thickness is inspected.

Blinding concrete is cast directly by using chutes fixed to the concrete mixer.

All reinforcing bars are cleaned from all foreign material (if any) adhered to the bars. Bars are

correctly assembled according to the Drawings by spacers to ensure the specified concrete cover

thickness. Formwork is assembled and firmly fixed by chains and turnbuckles to ensure no

movement or bulging occurs during concreting. Concrete is cast continuously by using concrete

pump to avoid cold joints and sufficient number of vibrators is used to ensure good compaction.

Curing with water spraying is carried out for the necessary period. The Engineers approval is

requested for the finished product and amendments are made if necessary.

Backfilling is carried out in a similar manner to the previously described backfilling of reinforced

concrete pipe culverts.

Excavation and bedding

for catch basins

Construction of

catch basin

(formwork, concreting)

Backfilling

Gravel layer and

blinding concrete


OCH to the City of Colombo Project Northern Section-1 Pa