Options to Improve Visual Amenity of Electrification

Phase 2 Output Report – Initial Assessment of Options W1001K-BBR-REP-EOH-000002-A04

Balfour Beatty Rail

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Table of Contents Abstract ........................................................................................................................................................................ 4

1. Introduction and Context ..................................................................................................................................... 5

1.1 AONBs Affected by GWEP .................................................................................................................................. 6

1.2 Review of Options to Improve Visual Amenity of Electrification in AONBs ....................................................... 7

1.3 Electrification Background .................................................................................................................................. 8

1.4 Series 1 .............................................................................................................................................................. 11

2. Technical, Functional and Assurance Requirements .......................................................................................... 12

2.1 Load Cases ........................................................................................................................................................ 16

2.2 Foundations ...................................................................................................................................................... 16

2.3 Functional Requirements ................................................................................................................................. 17

2.4 Brexit ................................................................................................................................................................. 18

3. RSSB Competition ............................................................................................................................................... 19

4. Landscape and Visual Impact Assessment ......................................................................................................... 19

5. OLE: Landscape and Visual Guidelines ............................................................................................................... 20

6. Series 1 Assessed against Visual Guidelines ....................................................................................................... 21

6.1 Options for Visual Improvement of Series 1 .................................................................................................... 21

7. Vegetation .......................................................................................................................................................... 28

8. Assessment Methodology of Options from Phase 1 report ............................................................................... 30

8.1 Basic Visualisations ........................................................................................................................................... 30

8.2 Assessment Table ............................................................................................................................................. 30

8.3 Design Principles Assessment ........................................................................................................................... 33

9. Phase 1 Options Review ..................................................................................................................................... 34

9.1 Relocating the ATF ............................................................................................................................................ 34

9.2 Lattice Booms and Cantilevers ......................................................................................................................... 35

9.3 Classic Headspan Design ................................................................................................................................... 35

9.4 Mix of Headspans and Portals .......................................................................................................................... 37

9.5 Alternative Headspan Designs .......................................................................................................................... 37

9.6 Improved Aesthetic Shape ................................................................................................................................ 37

9.7 Portal Structure – Radius (curved).................................................................................................................... 37

9.8 Braced Structure ............................................................................................................................................... 38

9.9 Viaduct back to back TTC’s/Portal .................................................................................................................... 38

9.10 Green Bridges ................................................................................................................................................. 38

9.11 Landscape Based Mitigation ........................................................................................................................... 39

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10. The Toolbox Approach .................................................................................................................................... 40

11. Selection Criteria ............................................................................................................................................ 41

12. Options Recommended for further development ......................................................................................... 43

12.1 Series 1 Amended ........................................................................................................................................... 43

12.2 Viaduct portal ................................................................................................................................................. 44

12.3 Viaduct Twin T ................................................................................................................................................ 45

12.4 ATF Options .................................................................................................................................................... 46

12.5 Landscape Based Mitigation ....................................................................................................................... 46

12.6 Colour and Surface Finishes............................................................................................................................ 47

13. Concluding Remarks ....................................................................................................................................... 48

14. Appendices ..................................................................................................................................................... 49

Appendix 1 Basic Visualisations of Options

Appendix 2 Assessment of Options

Appendix 3 RSSB Competition for Aesthetic OLE

Appendix 4 Moulsford and Gatehampton Solution

Appendix 5 Project Hazard & Risk Log

Appendix 6 Log of Issues from Advisory group

Appendix 7 GWEP Visual Amenity Glossary

Appendix 8 Headspans

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Abstract

a) The Great Western Electrification Programme involves erecting new Over Head Line Equipment

in a number of areas of Outstanding Natural Beauty. Electrification brings many benefits however

there may be an impact on visual amenity. Visual Amenity can be defined as - the visual aspects

of a location which contribute to its overall character and the enjoyment of residents or visitors.

Network Rail has commissioned Balfour Beatty to undertake a review of options to improve visual

amenity of electrification in Areas of Outstanding Natural Beauty.

b) This is the Phase 2 report of what is expected to be a 3 phase project. Phase 1, was an options

generation workshop that was held in February 2016. The workshop generated 79 different

options. An exercise was undertaken to consider each options against criteria based on

functional performance, safety and time. This review filtered out 35 of the 79 options as they did

not provide solutions that would meet critical requirements. Each option was then the subject to

an assessment. This considered the potential visual improvement and impact of implementing

each option. The result of this was the identification of 11 main options that have been taken to

this Phase 2 for further assessment.

c) Two additional commissioned activities have contributed to Phase 2, the development of,

Overhead Line Electrification: Landscape and Visual Guidelines and Landscape and Visual

Impact Assessments (LVIA). These have been used to help inform how any solution would

improve visual amenity. The LVIA work has enhanced and expanded the range of options

available to Network Rail. The development of the Landscape and Visual Guidelines document

provides a basis for designers to consider how best to apply the approved Series 1 catalogue.

d) This phase 2 report describes the assessment criteria and suggests 6 options for Network Rail to

consider. These options are Series 1 amended, Viaduct Portal and Twin T designs, ATF options,

Landscape based mitigations and Colour.

e) It is expected that before Phase 3 can commence Network Rail will assess these options and get

feedback from the Advisory Group and other stakeholders. This feedback will inform the final

nature and scope of Phase 3.

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1. Introduction and Context

a) The Great Western Electrification Programme (GWEP) currently undertaken by Network Rail

includes the installation of 25kV AC Overhead Line Electrification (OLE) through several Areas of

Outstanding Natural Beauty (AONB). GWEP is using the Furrer and Frey “Series 1” electrification

system. Balfour Beatty has been commissioned to undertake a review of options to improve the

visual amenity of electrification in these Areas of Outstanding Natural Beauty. This document is

the Phase 2 report of that commission. This report reduces the number of options identified in

Phase 1 and together with lessons learnt through the project makes recommendations for further

development.

b) The Government rationale for investing in a programme of electrification is to provide a railway

that is sustainable, has better stations and increased freight capacity. Electrifying the railway will

result in faster, greener, quieter and more reliable journeys. Electrification will improve services

and support economic growth, increase the number of seats on trains and improve system

reliability.

c) The performance of electric traction will contribute to shorter journeys. Journeys are smoother

and more comfortable. Electric trains have lower carbon emissions than diesel trains with no

emissions at the point of use, improving air quality particularly in areas such as city centres. They

are also quieter, improving air and quality of life for people living or working near the railway.

d) Electric trains are more reliable and require less maintenance. They are lighter than diesel trains

and cause less wear to the track, making the railway infrastructure more reliable. Electrification

supports economic growth. Faster trains with improved connections and more seats improve

access to jobs and services and open up opportunities for business.

e) The entire GWEP project is paid for wholly by public funds. Network Rail has a duty to minimize

costs to Government and the taxpayer whilst delivering the economic and environmental benefits

that the electric train service will bring. The Office of Rail and Road, the industry regulator are

responsible for holding Network Rail to account to provide good value for money, for passengers,

the freight industry and taxpayers.

f) As electrification will take place, then there will be some level of Visual Impact. This report

identifies some options to lessen the visual impact of electrification. A challenge for Network Rail

is the cost and benefit of an option for improvement.

g) Balfour Beatty has been commissioned to undertake a review of options to improve visual

amenity of electrification in Areas of Outstanding Natural Beauty. Visual Amenity can be defined

as - the visual aspects of a location which contribute to its overall character and the enjoyment of

residents or visitors.

h) The approach adopted is best summarised in the following quote “Natural England’s expectation

of this first part of the project is for engineers to identify ways to reduce the scale, mass, ‘clutter’

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and other sources of visual intrusion whilst still delivering an operationally safe and efficient

electrification scheme1”.

1.1 AONBs Affected by GWEP

a) The AONBs being considered as part of this review are:

Chilterns AONB & North Wessex Downs AONB;

Cotswold AONB.

b) The specific sections of the route are:

Four-track “Goring Gap” section from Tilehurst to Moreton Cutting

o (41m 27ch to 51m 77ch on MLN1)

Two-track section from Alderton Tunnel to Chipping Sodbury Tunnel

o (97m 57ch to 101m 06ch on SWB)

Two-track section from Box Tunnel to Batheaston

o (100m 78ch to 103m 62ch on MLN1)

c) The section of the route through the Chilterns AONB & North Wessex Downs AONBs (the

“Goring Gap”) includes the following listed structures for which specific approvals have already

been granted for the proposed electrification system design.

Gatehampton Viaduct (44m 00ch on MLN1);

Moulsford Viaduct (47m 27ch on MLN1).

d) A Landscape and Visual Impact Assessment (LVIA) is also been undertaken with inputs from an

advisory group established by NWR. A LVIA can assist decisions by identifying the effects of new

developments on views and on the landscape itself. In this project we are using the principles of

an LVIA to assist in the improvement process.

e) Due to the programme’s critical path (associated with the testing of new trains), electrification

equipment has been designed and installed along the section of line through the Chilterns AONB

& North Wessex Downs AONBs. This is not being considered as a constraint to the potential

options being considered by the study.

1 Andy Gale commenting on the Phase 1 report by e-mail 20/5/16.

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1.2 Review of Options to Improve Visual Amenity of Electrification in AONBs

a) Balfour Beatty’s commission to review options to improve the visual amenity of electrification in

Areas of Outstanding Natural Beauty was originally envisaged as a three phase report:

b) Phase 1: Workshop, generation of potential options and initial assessment2

c) The initial part of this was an options generation workshop that was held in February 2016. The

workshop generated 79 different potential options. These were generated against four

categorisations.

d) A filtering exercise was undertaken that considered each of these options against criteria based

on the functional performance, safety and time to implement criteria. This review filtered out 35 of

the 79 options as they did not provide solutions that would meet critical requirements.

e) Each option was then the subject of an initial assessment. This considered the potential visual

improvement and impact of implementing each option. The result of this assessment was the

identification of 11 main options (plus further associated sub options) that it was proposed to take

into Phase 2 for further assessment.

f) Phase 2: Further refinement, predominantly development of visual images and technical review.

g) Two additional commissioned activities have contributed to Phase 2, namely the development of,

Overhead Line Electrification: Landscape and Visual Guidelines3 and Landscape and Visual

Impact Assessments (LVIA). These are being used to help inform how any new solutions would

improve the visual amenity.

h) Although the LVIA was not originally envisaged as part of this commission, the LVIA work has

enhanced and expanded the range of options available to Network Rail. Additionally the

development of the Landscape and Visual Guidelines document provides a basis for designers to

consider how best to apply the approved Series 1 catalogue.

i) Phase 3: Following completion of Phase 2 and the LVIA further development of the options is

anticipated.

j) Through each of these phases it is anticipated that the number of options under consideration will

reduce, resulting in a small number of viable options at the end of Phase 3.

2 Phase 1 Output Report – Preliminary Review of Options, W1001K-BBR-REP-EOH-000001-AO1

3 Overhead Line Electrification: Landscape and Visual Guidelines, 2B Landscape Consultancy Ltd. July 2016

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1.3 Electrification Background

a) The advantages of electrification have been long recognised. The Weir Committee on the

electrification of railways in 1932 reported on the advantages at the time of electrification of the

UK network. Figure 1 illustrates that the UK lags behind other developed countries in terms of

percentage of the national network electrified.

FIGURE 1 ELECTRIFICATION INTERNATIONAL COMPARISONS

b) The UK railway network is one of the world’s oldest. Consequently it follows alignments designed

for the steam age and has a smaller structure gauge than more modern railways. It serves a

relatively wealthy and densely populated country. To electrify the network whilst maintaining a

train service is a complex task.

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FIGURE 2 UK ELECTRIFICATION OVER THE LAST 70 YEARS AND PROJECTED TO 2020

c) In 2009 Network Rail commenced development work for the New Electrification Programme. It

was recognised that new OLE systems were needed. This was due primarily to the reliability and

performance limiting aspects of existing and legacy OLE types. Some 97 items areas for

improvement were identified and these are summarised as: -

o Improve design life and reliability of mechanical system, Neutral Sections, MIR’s etc;

o Improve the reliability of electrical connections;

o Design for maintainability, improve maintenance efficiency;

o Improve constructability efficiency & build quality (conventional construction practices & new

high output trains);

o Reduce material supply chain complexity;

o Clarify allocation design principles and maintain platform for design development & evolution.

d) The development was given further impetus by a number of electrification related improvement

notices in 2011. Issues requiring Improvement included;

o Isolation & Earthing safety concerns;

o Insufficient ‘safe by design’ awareness;

o Electricity at Work Regulations (EaWR) - compliance issues;

o Contact wire height;

o Level crossings;

o Operation of RRV’s under live OLE;

o Risk assessments;

o Lack of operation & maintenance strategy;

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e) The New Electrification outcomes or systems developed are summarised below.

Series 2

Suitable for multi-pan up to 110mph

Tensions 12kN/14kn (120mm) 110mph

Tension 11kN/11kN (107mm) 90mph

Series 1

Suitable for multi pan up to 140mph

Tensions 16.5kN/13kN 140mph

New UK Master Series

125mph 15kN/12kN OLE system

To incorporate Series 1 and 2 into a single design range

Single platform for maintenance and development

f) A significant development is the Autotransformer System. This is the way that power is supplied

from the National Grid via feeder substations to the line. Existing systems require booster

transformers fixed to masts every 3-8 km. These can have a negative impact on the visual

amenity. The Autotransformer System removes the need for booster transformers and reduces

the number of feeder substations.

g) The wire tensioning system is improved to increase reliability. The systems also require fewer

wires.

h) The dynamic nature of electrification engineering can be appreciated by noting the following

recent changes to statutory provisions and standards, which the above systems can cater for;

o 2010 – Common Safety Method replaced safety verification part of ROGS

o 2012 – Railway Interoperability Regulations & associated TSI’s became applicable to all NR

infrastructure projects

o Combined Energy TSI issued Jan 2015

o EN 50122 ‘annexe G’

o Issue of National Notifiable Technical Rules – GL/RT1210, March 2015

o ORR enforcement and compliance to Electricity at Work Regulations

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1.4 Series 1

a) Series 1 is the designed solution (but not necessarily exclusive) for GWEP. The Great Western

Mainline warranted a new design not only due to the requirements mandated by the Dft and

Standard but also the historical legacy issues. These include structures and the route corridor

width including distances between tracks.

b) The Series 1 system is an Auto Tension 25kV 50 Hz AC system for operation at train speeds of

up to 225 km/h (140mph) with multiple pantographs. Series 1 is optimised for installation with

High Output Plant System (HOPS) to maximise construction efficiency by minimising time

required to be spent on track. Series 1 can also be installed using conventional methods. The

system is designed to support adjacent line open (ALO) operations thus increasing availability

and efficiency. Many of the system principles are developed upon best practice taken from the

proven Swiss FL200/260 system and the GEFF system installed on the Network Rail Great

Eastern Route since 20094.

c) The Series 1 OLE system includes:

o OLE structures and baseplates

o All components connecting the OLE wires to the structures

o All tensioning and anchoring components

o Wires themselves, including ancillary wires

o Connections to isolators

o Connections to earth return bonds

o ATF Arrangements and wires

d) The Series 1 OLE system does not include:

o Distribution or protections equipment or transformers

o Control or SCADA systems

o Signalling or track equipment

o OLE foundations

o Custom structures i.e. connections to viaducts or tunnels

o ROCS (conductor bar arrangements)

o High level feeds

o RSC and associated connections

4 MAN001 System Description Manual v5.1 118049-FAF-MAN-EOH-000004

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2. Technical, Functional and Assurance Requirements

a) The purpose of this section is to briefly describe what the system does and requirements are that have to be delivered by OLE.

b) Electrical Power generated at a power station is transmitted via transformers into overhead

transmission lines at high voltage owned by the National Grid. The power is taken by NWR from the National Grid at feeder substations, which then transmit the power to the OLE. 25,000V is the optimum voltage for main line trains.

c) Masts and gantries support the overhead “contact” wire carrying the power. The power is transmitted from the contact wire to the train by a sprung ‘pantograph’, which is attached to the roof of the moving train. The circuit is completed through the train wheels to the rails and then by connecting the rails back to the feeder substation.

d) The contact wire must be held at a designed tension a designed position, vertically, horizontally and longitudinally. All of the structures are designed to support this objective and manage the static, dynamic and thermal forces that can be applied.

e) Overhead line equipment comprises of many components. As stated the primary purpose of these components is to maintain contact wire in its designed position enabling the power to flow to the train. A stable contact wire will result in less wear of the system. The contact wire is tensioned between support structures in to minimise deflection by high winds and temperature variation.

f) The contact wire is suspended from vertical cables called droppers that are supported by the catenary cable. The catenary and contact wire span between support structures which are normally approximately 50m apart. The wires are normally about 1500m long and tensioned at either end. To ensure no loss of power, adjoining sections of wire overlap for about 180m.

Distance Between Supports ~ 50m (portal frames or cantilevers)

Catenary cable carries the Contact Wire

Contact Wire hung from droppers

dropper dropperdropper

Tension

FIGURE 3 CATENARY, DROPPER AND CONTACT WIRE

g) In designing the supporting structures, the most important engineering consideration is the effect

of high wind. The supports are made sufficiently stiff so that they do not deflect enough to impair current collection.

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h) The contact wire runs in a zig-zag path above the track to avoid wearing a groove in the pantograph. The zig-zag - known as the ‘stagger’ - is generally achieved by the use of ‘pull-off’ arms attached to the support structures.

FIGURE 4 CONTACT WIRE STAGGER

i) Where there are one or two tracks, OLE is normally supported from lineside masts using cantilevers. The catenary cable and the pull and push-off arms supporting the contact wire are attached to the ends of the cantilever. Insulators are required to separate the electrically live elements. The earth wire is normally attached to the mast.

Foundation

Mast

Cantilever

Pantograph

Pull Off Arm

FIGURE 5 LONG REACH TWIN TRACK CANTILEVER STRUCTURE

j) Where there are more than two tracks a steel portal frame can be adopted. This does not

preclude the of cantilever structures. Adoption of a TTC can enable work with the Adjacent Line Open (ALO). ALO can avoid the necessity to completely block the line to traffic. The cantilever being smaller than a boom also allows smaller plant to be used for its installation. The portal frame consists of two masts joined by a horizontal boom.

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Contact Wire

Mast

Stanchion or

Column

Boom

Span

Foundation Foundation

Earth

Wire

Auto

Transformer

Catenary Cable

Drop

Tube

FIGURE 6 PORTAL FRAME STRUCTURE

k) Historic and legacy overhead electrification uses a system of wires spanning between masts either side of the tracks to support the OLE catenary and contact wires, known as ‘headspans’. These systems rely on tension only and are incapable of providing independent stability for each line. For example Series 1 in contrast includes components that can utilise both compressive and tensile properties.

l) The catenary and contact wires are installed in lengths that are tensioned at either end in order to keep the contact wire as stable as possible. This is so that a good contact is maintained with the pantograph at all times. The tensioned wires will generally be up to 1500m long. An overlap between the lengths of wires of 180m up to 195m provides a continuous supply of electricity to the trains.

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FIGURE 7 MODERN TENSIONING SYSTEM (TENSOREX C+)

m) The traditional common tensioning mechanism consists of a braced mast and pulleys with iron

weights. Recent systems use a spring tensioning mechanism. Each wire needs two springs at each end (one for the catenary and one for the contact wire) and these are attached above the track to frames spanning the line. These supporting frames are larger than typical OLE structures because of the greater forces at work. Following the Potters Bar derailment of 10th May 2002, a recommendation was made to review the arrangements for securing balance weights on overhead line equipment.

n) At the midpoint along a tensioned length, the wires are fixed in place. This is called the midpoint anchor and its purpose is to resist the effect of the friction caused by the passing pantograph trying to drag the contact wire forward. Midpoint anchor structures are likely to be portal frames that are slightly bigger than typical OLE structures.

o) OLE support structures are generally spaced 50–60m apart and need to follow the track alignment. Where the line goes around a horizontal curve there may be a need to space them closer together so that the contact wire is kept in its designed position relative to the track. The same principle applies to vertical curves where track changes gradient.

p) Neutral sections are electrical “gaps” in the OLE wiring, used to isolate sections of wiring for maintenance purposes and to separate sections supplied with power from different feeder stations. This prevents power from one feeder passing via the OLE to another. Neutral sections are formed by inserting short electrically-isolated or non-conducting elements between lengths of live contact wire, and fitting the catenary wire with insulators.

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2.1 Load Cases

a) The OLE system is designed to maintain the contact wire in its designed position within given

tolerances or deflection limits. The structures are designed to do this and the designer must include the following load cases in his design.

Self-weight of the structure

Self-weight of the conductors and supported equipment

Radial tension of the wires, max at low temperature

Radial tension of the wires, min at high temperature

Wire run Tension along track

Lateral wind Ultimate Limit State (ULS) on the conductors

Lateral wind Serviceability Limit State (SLS) on the conductors

Wind ULS in transverse (-x) direction on structure

Wind SLS in transverse (-x) direction on structure

Wind ULS along track, (y-direction) on structure

Wind SLS along track, (y-direction) on structure

Ice on wires, 9.5 mm radial (not contact wire)

Ice on structure, 9.5 mm radial Broken Wire

2.2 Foundations

a) The primary purpose of the masts and portals is to maintain contact wire in its designed position

enabling the power to flow to the train. The foundations are required to ensure the structures do

not settle, deflect or rotate beyond predefined limits for any load case. Foundations may vary

depending upon ground conditions, the structure to be supported and the load cases for that

structure.

b) Network Rail and the GWEP project have a preference for steel tubular piles as a foundation.

Steel tubular piles have been aligned with the high output methods and plant. They allow the

foundation to be installed within a single shift and can be loaded immediately. They are also a

more sustainable option than a concrete alternative as the material has a smaller direct carbon

and they can also be extracted (with difficulty) and re-used if required.

c) For each structure type (cantilever or portal) it is necessary to calculate overturning moments,

axial loads, across track and along the track as well as shears and torsional effects on the

foundations for all ULS and SLS design criteria and in accordance with BS EN 50119 and client

standards.

d) An implication is that although the existing foundations may in theory be reused for a new

structure a design calculation will still be required. This is because the foundation will be subject

to a different load case. An example may the replacement of a portal structure with a cantilever or

headspan the load and loads paths in the foundation would need to checked for this new

condition.

e) The foundation and superstructure design must also allow for construction tolerances.

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2.3 Functional Requirements

a) Functional requirements define what the project must deliver and thus provide a benchmark

against which success or otherwise can be assessed. The project has a set of functional

requirements. The identified options are assessed as part of each phase to ensure that the

solutions that are progressed can meet these requirements. The functional requirements include

compliance with:

Standards - EU legislation Technical Specification for Interoperability (TSI) and Railway

Group Standards

Department for Transport (Dft) rolling stock strategy (i.e. need to be able to run IEP & EMU

trains on specified dates)

Future linespeed and traffic requirements

Sectional running times

Gauging

Route availability in terms of traffic aspirations and capacity

Performance and reliability

b) Other factors that have been included in assessing the options are:

Access requirements to install and maintain the equipment;

Safety; and

Timescale for design, development and installation.

c) The following are mandatory requirements

European and National Legislation (Electricity at work Regulations 1989 highlighted for

prominence)

Railway Group Standards

Network Rail Company Standards

Network Rail Asset and environment policies

Great Western Electrification Programme Project Requirements Specification GRIP 3-85

The requirements of applicable temporary non compliances pending standard change for

Group and company Standards

BS EN 50126:1999, Railway Applications. The specification and demonstration of reliability,

availability, maintainability and safety (RAMS), covering Validation and Verification.

British and European standards where referenced within Technical specifications for

interoperability or in Railway Group standards.

d) Whole life cost is not directly a functional and were excluded from the initial assessment. This

was to ensure that no options were ruled out on the grounds of cost during the Phase 1

assessment. It was also been agreed that cost will be excluded from the Phase 2 assessment.

Cost will be considered in the next phase.

e) Technical specifications for interoperability (TSIs) mean the specifications by which each

subsystem or part of subsystem is covered in order to meet the essential requirements and to

5 CCMS ref: 118049-INF-SPE-EMF-000002

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ensure the interoperability of the European Community's high speed and conventional rail

systems.

2.4 Brexit

a) The referendum result on Britain's membership of the European Union (EU) does not have any

immediate impact for the Railway Safety and Standards Board (RSSB), its members or the wider

rail industry in this country. While the UK is still a member of the EU, obligations and

requirements still need to be met by duty holders.

b) RSSB believes that the rail industry's strategy for standards is unlikely to change, since

standards exist to help companies meet a range of obligations, many of which exist whether in or

out of the EU. If the UK retains its commitment to open global markets and reduced barriers to

trade across Europe and beyond, our members and their supply chain will still want to buy and

sell relevant products and services efficiently. It is unlikely that UK participation in European-level

standards committees will change. Many of these committees exist outside of the EU

constitutional framework and already involve non-EU countries6.

6 RSSB Interim Managing Director Mark Phillips Press release 29th June 2016

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3. RSSB Competition

a) The desire to make the design of gantries and cantilever structures more aesthetically pleasing

has been recognised by others.

b) The rail industry’s Enabling Innovation Team, which forms part of the Future Railway programme,

has teamed up with HS2 to promote a competition through the Royal Institute of British Architects

(RIBA).

c) The competition, funded by Department for Transport - has looked for ideas to improve the

appearance of overhead line electrification on a two track railway. Out of 44 entries there were 10

shortlisted and of these ten, three are being taken forward to the next stage.

d) The entries are illustrated in appendix 3. It is possible to see how the general design principles

have been applied to these.

e) This competition is taking place separately to this project, however it is recommended that

Network Rail maintain a watching brief and encourage crossover of ideas.

4. Landscape and Visual Impact Assessment

a) A Landscape and Visual Impact Assessment (LVIA) is used to assist decisions by identifying the

effects of new developments on views and on the landscape.

b) Industry standard guidelines published by the Landscape Institute presents a statement of the

principles of assessment. These offer advice on the practice and process of assessing the

landscape and visual effects of changes and their significance. The LVIAs for this project are

being carried out by a Landscape Consultant familiar and competent in this approach.

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5. OLE: Landscape and Visual Guidelines

a) When this project commenced there were no guidelines against which to assess options for

improving visual amenity. The Overhead Line Electrification: Landscape and Visual Guidelines

produced by 2B Landscape Consultancy Ltd have addressed this issue.

b) The following summarises the design principles.

Consistency: Seek consistency of form, associated elements, and distances between gantries.

Use a single gantry design type within any locally visible area.

Simplicity: Supports, insulators, conductors and related structures should be as visually simple

as possible.

Consider the design of consequential OLE-related structures such as raised bridges, sub-stations

and track-side fencing and use appropriate materials and colours.

Minimise:

Overall height: this can be important in cuttings, where, as a result of the addition of the

OLE, the route of the rail line becomes visible; and in open areas, where taller structures

increase projection above the horizon ('skylining');

Apparent thickness of masts, stanchions, beams and supports. Simple, slim lines are

always preferable to reduce visual impact;

Visual clutter generally: such as apparently random variations in extension height of

posts; or projecting elements such as beams, posts, brackets and ATF supports;

The additional impact of the ATF by relocating to ground or a lower level where technical

constraints allow.

Vegetation clearance

Location of major elements

Avoid locating gantries where they would form a focal point in directed views, for example at the

end of a street or central to a view from a property.

Complex elements: Locate more complex and variant structures (such as tensioning gantries and

overlaps) in hidden locations (for example cuttings, between groups of trees etc).

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6. Series 1 Assessed against Visual Guidelines

a) The BB commission to explore options to improve Visual Amenity commenced with the remit of

determining structures with greater visual amenity than the “Series 1” design.

b) As this project has developed it has become informed by both the Overhead Line Electrification:

Landscape and Visual Guidelines and the findings emerging from the LVIAs. This has allowed us

to retrospectively look at the Series 1 with particular visual design principles in mind.

c) Five concepts for the visual improvement of Series 1 are illustrated and described below.

6.1 Options for Visual Improvement of Series 1

Concept 1

As Designed Options for Visual Improvement

Option 1

Option 2

Visual Design Principles (see Guidelines) 2.5 Simplicity: Supports, insulators, conductors and related structures should be as visually simple as possible. 2.7 Minimise: • Overall height: this can be important in cuttings, where, as a result of the addition of the OLE, the route of the rail line becomes visible; and in open areas, where taller structures increase projection above the horizon ('skylining'); • Visual clutter generally: such as apparently random variations in extension height of posts; or projecting elements such as beams, posts, brackets and ATF supports;

Proposed changes In this example overall height is reduced by 1227mm by reducing the height of the mast. The earth wire position and fixing method is not altered. Instead of suspending the ATF from the “gibbets” the insulator is redesigned to be supported on the cantilever. In Option 2 the small parts steelwork are suspended from one point further reducing visual mass and clutter.

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Note: Where fixed type ATF supports are used there is a risk of different tensions occurring between long and short spans leading to bending and twisting forces in the masts. The ATF can be supported on “fixed” or one of several “suspension” arrangements depending on local loading and dimensions of existing mast dimensions. (MAN001 System Description Manual v5.1 118049-FAF-MAN-EOH-000004)

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Concept 2

As Designed

Option for Visual Improvement

Visual Design Principles (see Guidelines) 2.5 Simplicity: Supports, insulators, conductors and related structures should be as visually simple as Possible. 2.7 Minimise: • Overall height: this can be important in cuttings, where, as a result of the addition of the OLE, the route of the rail line becomes visible; and in open areas, where taller structures increase projection above the horizon ('skylining'); • Visual clutter generally: such as apparently random variations in extension height of posts; or projecting elements such as beams, posts, brackets and ATF supports;

Proposed changes In this concept the overall height is reduced by reducing the height of the stanchions. The earth wire position and fixing method is not altered. Instead of supporting the ATF from the extended mast the insulator is redesigned to be supported on the cantilever. The opportunity is taken to suspend the small parts steelwork from one point further reducing visual mass and clutter.

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Concept 3

As Designed

Option for Visual Improvement

Visual Design Principles (see Guidelines) 2.5 Simplicity: Supports, insulators, conductors and related structures should be as visually simple as possible. 2.7 Minimise: • Overall height: this can be important in cuttings, where, as a result of the addition of the OLE, the route of the rail line becomes visible; and in open areas, where taller structures increase projection above the horizon ('skylining'); • Visual clutter generally: such as apparently random variations in extension height of posts; or projecting elements such as beams, posts, brackets and ATF supports;

Proposed changes In this example overall height is reduced by reducing the height of the stanchions. The ATF and earth wired are tensioned Instead of supporting the ATF from the extended mast the insulator is redesigned to be supported on or from the boom. The opportunity is taken to suspend the small parts steelwork from one point further reducing visual mass and clutter. Penalties for such an option could include lack of maintenance access and an increased need for isolations.

Why is the ATF suspended so high up? the answer is The ATF is not automatically a tensioned cable therefore allowance has the be made for at the mid-point between supports for: 1 Max and minimum sag due to temperature variation 2Blow off (wind loadings) 3 Ice 4 Electrical clearances. If the ATF (and the earth) could be tensioned and that tension maintained. The height of the structure support the ATF could be reduced. The AFT could potentially be supported on the underside of the boom or cantilever with potential productivity gains. The straightening of “lines” would make for a more graceful appearance.

The height of the ATF is dependent on several factors including clearance from ground level, rail level, nearest live wires, local obstruction and isolation combinations. As a result nominal ATF heights are not specified as part of Series 1 and are defined by the client on a route or national basis. (MAN001 System Description Manual v5.1 118049-FAF-MAN-EOH-000004)

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Concept 4

a) The following option for improving visual amenity is perhaps the most challenging. It does

suggest an evolutionary approach and can lead to a reduction in the number of components.

As Designed Options for Visual Improvement

Option 1 Single Insulator Cantilever Laterally offset from the boom

The Single Insulator Cantilever (SIC) is attached to the boom by a SHS drop tube. An along track hinge is provided at the flange connection points.

Option 2 Goose neck and registration arm laterally offset from the boom.

Visual Design Principles (see Guidelines) 2.5 Simplicity: Supports, insulators, conductors and related structures should be as visually simple as possible. 2.7 Minimise: • Overall height: this can be important in cuttings, where, as a result of the addition of the OLE, the route of the rail line becomes visible; and in open areas, where taller structures increase projection above the horizon ('skylining'); • Visual clutter generally: such as apparently random variations in extension height of posts; or projecting elements such as beams, posts, brackets and ATF supports;

Proposed Changes This concept is based on using the existing boom or cantilever to support the SIC or indeed the goose neck only.

Factors to Consider Electrical clearances are a significant consideration in this concept and therefore the possibility of using new insulated materials may be considered. Maintenance effects on track lifts. Would make this suitable with high fixity track.

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Concept 5

As Designed

Option for Visual Improvement

Visual Design Principles (see Guidelines) 2.5 Simplicity: Supports, insulators, conductors and related structures should be as visually simple as possible. 2.7 Minimise: • Overall height: this can be important in cuttings, where, as a result of the addition of the OLE, the route of the rail line becomes visible;

Proposed Changes The SIC is integrated into the boom. The height of the masts are minimised saving over 3m in height. The ATF is supported on the boom.

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and in open areas, where taller structures increase projection above the horizon ('skylining'); • Visual clutter generally: such as apparently random variations in extension height of posts; or projecting elements such as beams, posts, brackets and ATF supports;

Factors for consideration. Track Maintenance lifts are limited. Tracks at different levels would all need to be catered for ad supported within the boom. This would likely exclude locations where tracks are at greatly different levels. Electrical clearances will require further investigation.

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7. Vegetation

a) Established vegetation is likely to be one of the most effective forms of mitigation so it is

desirable to minimise losses wherever possible and to determine where establishing vegetation

will improve visual amenity. The railway will be more prominent after OLE is installed if vegetation

that provided screening is removed. However it is necessary to remove vegetation to avoid the

risk of trees and shrubs interfering with or falling on the OLE, and reduce the risk of lineside

fires7.

b) The Phase 1 report made a recommendation to review electrical clearances with a view that this

may enable a reduction in extent of lineside vegetation clearance. It was felt that by reducing the

extent the visual impact would be reduced. However NR have advised that the de-vegetation has

already taken place.

c) Vegetation has more than just visual amenity implications. These include electrical clearances,

signal sighting, leaf fall, risk of trees blown over onto track and OLE. Furthermore vegetation has

the potential to stabilise or destabilise embankment and cuttings. The intervals between

vegetation clearances need to be considered, e.g. the closer vegetation is allowed to spread

towards the track the more cutting back will be required.

d) Network Rail Standards8 mandate a vegetation risk assessment to determine the risk to the

infrastructure and operations from vegetation shall be assessed based upon;

Leaf fall and adhesion

Presence of large and/or dangerous trees

Other hazards relating to the presence of vegetation (see earlier paragraphs)

e) Vegetation management regimes vary according to the risk posed by the line-side vegetation and

the characteristics of the railway. The potential risk from vegetation is managed in the following

areas;

Ballasted areas

Cess

Three to five metres from running rail

o Allowance has to be made for the growth of vegetation.

Five metres to boundary

7 Network Rail, A Guide to Overhead Electrification, 132787-ALB-GUN-EOH-000001, Feb 2015 Rev 10

8 NR/CS/TRK/0520 and NR/L2/TRK/05201

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FIGURE 8 VEGETATION CLEARANCE WHEN LINESPEED > 60 MPH

FIGURE 9 VEGETATION CLEARANCES AROUND AC OLE

f) Vegetation shall be maintained 3.5 metres clear of live parts of the OLE and the infinite vertical

space above them as shown in Figure 9. In figures 8 and 9 red represents the area in which

vegetation is prohibited and amber where maintenance intervention is required.

g) Given the known risks of vegetation and the fact that clearance has been undertaken the author

considers no further review of clearances is appropriate.

h) The landscape architect has recommended that there may be specific locations where a strip of

land (subject to ownership and agreements) could be used for planting trees or hedging may be

useful.

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8. Assessment Methodology of Options from Phase 1 report

a) The following section outlines the methodology adopted for assessing the 11 options identified in

phase 1 for further investigation.

Demand

Improvement of Visual

Amenity

Controls

Legislation

Regulation

Standards

Functional-

requirements

Determine, Explore

and Assess Options

Resources

People, skills

Research

Resources

Finance

Guidelines

Product

A Range of Options

(Toolbox)

Environment

FIGURE 10 VISUALISATION OF APPROACH

8.1 Basic Visualisations

a) For each of the options being considered, a basic visualisation has been generated. These are

provided within Appendix 1. These visualisations allow comparisons to be made between the

different options.

8.2 Assessment Table

a) Each of the options has been listed in an assessment table, (Appendix 2). The solution is

assessed to determine if it would provide improvement for each of the given situations.

The options are then assessed against the following criteria.

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b) Visual Improvement close up looking down or distant; This acknowledges the fact that visual

improvement will to some extent be dependent upon the position of the receptor. Ideally a

solution that improves visual amenity from all perspectives would be preferred.

c) Functional Requirements; The functional criteria are described earlier in this document. As part

of the assessment these have been broken down to review the initial impact or installation and

also the longer term effects through operation and maintenance, where relevant.

d) Timeframe develop and approve manufacture and install; Within the structural options, it has

been assumed that the approved Furrer & Frey Series 1 equipment (i.e. small parts steelwork

and catenary system) will be used. This should limit the scope of any approvals to the supporting

structure only.

e) All designs and developments require some form of approval. Approval often demands cross

discipline review, prototyping and testing before installation into operational use. To minimise

approval requirements, this project assumes the utilisation of the existing approved Series 1 Sub

Systems (i.e. the small parts steelwork). The reason for this is that, major structural elements are

the most visually intrusive and design of these would not require the redesign of the whole

system.

f) Expected Reliability; Reliability9 is the probability that an item (or system) will perform its

intended function for a specific period of time under a given set of conditions. The reliability

criteria have been clearly defined in the Project Requirements Specification for the Great

Western Electrification Programme. Network Rail have placed significant emphasis on the need

to ensure the system design excludes “features that are known to result in multi-track disruption

in the event of a single component failure” (118049 PRS – 2762).

g) In designing the Series 1 system NWR have applied the principles of reliability analysis, which

includes;

Identification of critical components

Use of available data from previous OLE design and analysis

Establish base condition for component

Define performance modes in terms of past levels of unsatisfactory performance

Calibrate models to experience (testing at Old Dalby)

Model reasonable maintenance and repair scenarios

h) Access; OLE construction usually follows the following stages;

Ground investigation, trial pits

Design

Foundation installation

Mast erection

Boom erection

Small parts steel work

9 EN 50126:1999

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Ancillary wires

Catenary and Contact Wire

Registration

i) When these stages of work are being carried out access is required to one or more tracks. The

preferred option is to use the High Output Plant system.

j) An added complication occurs where the OLE equipment has already been erected and

electrified. To replace a portal will require all four roads (e.g. Goring Gap) to be blocked. The

existing OLE will be dismantled and then re-erected on the new structure.

k) On an operational electrified railway this will have significant operational implications. The work

will demand blockades. Although blockades disrupt the railway they do potentially increase the

possibility of re-using previously installed equipment.

l) It is likely that in this scenario the existing foundations cannot be reused due to the complexity

and time required to dismantle, remove and replace. For example on a operational railway for a

portal structure to be replaced, all lines would need to be blocked, all OLE removed and the

structures dismantled before the new one could be erected.

m) Other Environmental; In this section we consider the other environmental implications of the

option. This can include additional construction traffic, night time working and noise.

n) Safety build operate and maintain; NR is obliged to ensure Safety is considered during the design

and construction stages. “Safety by Design” encourages a designer to "design out" health and

safety risks over the whole life of the system. The concept supports the view that along with

quality, programme and cost; safety is determined during the design stage.

o) Within the UK, construction designers are legally bound (e.g. through the CDM 2015 regulations)

to design out risks during design development to reduce hazards in the construction and end use

phases of a project.

p) Use of Existing Masts and Bases; It is unlikely that existing masts and bases can be reused. The

first priority is to keep the railway operational. Without extended possessions or blockades

existing masts and bases could not be used. Furthermore de-risking a project of this complexity

would dictate new foundations and structures were installed before the contact and catenary

wires are transferred to the new structures.

q) Other factors could also preclude the reuse of mast and bases. The new design may require

shorter or longer distances between masts along the track. The construction and operational

practicalities could also prevent their reuse. For example the time available may not be enough to

do the volume of work required.

r) Erecting new booms over existing wires on an operational electrified railway has significant

logistical issues. There will be a lot of existing OLE that will have to be worked around.

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s) Comment on hazards; A project hazard log is included as Appendix 5. This is a high level log and

aims to capture the major issues.

8.3 Design Principles Assessment

See Appendix 2 Sheet 3 Design Principles Assessment

a) In this assessment each option is assessed against the Design principles described in the

Landscape and Visual Guidelines document. Against each option the following questions are put.

Does the option provide consistency?

of form

distances between gantries

a single gantry design type

Does the option offer simplicity?

Supports, insulators, conductors and related structures should be as visually simple as possible.

Consider the design of consequential OLE-related structures such as raised bridges, sub-stations

and track-side fencing and use appropriate materials and colours.

Does the option minimise:

Overall height:

Apparent thickness of masts, stanchions, beams and supports.

Visual clutter

A qualitative assessment is given.

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9. Phase 1 Options Review

a) A report setting out the Phase 1 Outputs – Preliminary Review of Options has been issued. This

recommended that 11 main options (including associated sub options) be taken forward for

further assessment together with undertaking of a Landscape Visual Impact Assessment (LVIA)

and consideration of landscape mitigation measures.

b) Network Rail has shared the Phase 1 Report with the AONB stakeholders. The 11 options to be

taken forward in phase 2 are listed in the table below.

Option Reference Description

G416/G416b This is a rigid headspan structure with options of relocating the ATF.

AS1/AS2 This is to amend the structure with more graceful members in line with the design principles.

VTTC/VP This is the Moulsford Viaduct solution

PSC This option is curved portal frame.

N108 This is the standard headspan.

SL1 This is a standard lattice beam.

ATF This option removes the ATF and the upstands.

N109 This option involves bracing the structure to make smaller.

A203 This is a green bridge or tunnel solution.

A106 This is a mix of headspans and portals.

P5 This option suggests painting or amending the finish of the structures.

TABLE 1 OPTIONS IDENTIFIED IN PHASE 1 TO PROGRESS

9.1 Relocating the ATF

a) This option is scoring quite highly on improving visual amenity.

b) The ATF (Autotransformer Feeder) System is the system used for supplying power to the OLE. It

incorporates ATF cables, generally one per track, attached to OLE masts and connected to

autotransformer stations at intervals alongside the track.

c) The purpose of relocating the ATF to ground level is to reduce the “visual mass” of the overall

system.

d) The ATF can also be lowered and this may be beneficial where track is in a cutting and but for

the ATF the OLE would be “invisible”.

e) Relocating the ATF from the masts of and shortening of the masts is technically feasible. This is

also a sub-option in many of the other options.

f) From a practical point of view this is not an easy option. The cable weighs 50kg/m and therefore

cannot be handled manually. It will need to be protected from damage. There are a number of

other key issues associated with this option:

Interference/emc issues with signalling and telecoms cabling

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Requirement to insulate/trough separate to existing cabling and hence cost

Safety considerations – potential cable strikes

Land availability

Condition of the embankment e.g. suitability as a foundation

9.2 Lattice Booms and Cantilevers

a) These structures have been used elsewhere in Europe. As open lattice structures, the Series 1

booms and cantilevers might have been expected to be less visible than they are. It is thought

that a lattice construction could be less visible if it employed the more traditional approach of thin

diagonal rods linking members to carry shear and torsion.

b) The Series 1 lattice form has been designed for its structural purpose. There is an option to seek

less visible alternatives, with reduced depth booms, that retain the required structural strength.

9.3 Classic Headspan Design

a) In terms of visual amenity, the existing Standard Headspan (N108) design (consisting of

tensioned wires) was considered to score high visually. This is likely to be due to the perceived

visual mass, less clutter, simplicity and clearer lines.

b) A further possible advantage of headspans in the Visual Amenity context was the suggestion that

it may be possible to convert portal structures to headspans. This is unlikely to be possible for

reasons described below.

c) The overall height of the mast is likely to increase, potentially making the railway more visible,

increasing the zones of theoretical visibility and increasing the likelihood of “skylining”. The

apparent and actual thickness of the masts is also likely to increase.

d) The consequences of a failure in such a system affect all tracks. As such, the standard headspan

is not an acceptable option for a 140mph railway with trains using multiple pantographs with a

higher tension in the OLE wire than the classic UK systems.

e) As this solution cannot support the Series 1 equipment, dynamic modelling will be required if this

option is to be progressed any further. The dynamic modelling would involve a dynamic

simulation model to indicate if it would be suitable for the design speed. An assessment of

interface effects, practicality and quality would also need to be considered.

f) The Headspan option does not comply with the reliability and safety requirements and therefore it

is recommended that this option is not viable.

g) The contact wire tensions are greater on GWEP than that achieved on traditional headspan

systems. This will create added complexity for the anchor structures.

h) Further information on classic Headspans and reason for rejection is given in Appendix 8.

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17770

Standard 4 Track Headspan

FIGURE 11 PORTAL STRUCTURE COMPARED WITH STANDARD HEADSPAN

i) The perceived visual improvement of a headspan structure may not actually be achieved in

practice. In Figure 11, a built portal structure is compared with a standard 4 track headspan on

straight and level track. This figure shows that the headspan required for a particular location

would be different from the standard straight and level track on the same plane. Local factors

such as cable troughs may dictate what is actually possible. The portal structure spans a wider

distance than the headspan even allowing for end throw and centre throw. The head span masts

are taller than the portal structure masts. On GWEP the 6fts (distance between a two tracks) and

10ft (distance between a pair of two tracks) vary and achieving the minimum headspan width

shown in Fig 11 will not be achievable. The implications are higher masts, new foundations and

greater tensions required.

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j) The headspan masts have also to be designed to resist the tensile forces in the cross wires, in

addition to the wind and other loading cases. To maintain the contact wires in their designed

vertical positions will demand high tensions. The boom on the portal structure is an efficient

structure for minimising deflections.

k) Even before we consider speed, safety and reliability, the immediate implication of this is that the

headspan masts will need to be of a bigger section and taller. This will demand deeper and more

robust foundations. This has cost and time implication as well as potentially ruling out the reuse

of already constructed foundations.

9.4 Mix of Headspans and Portals

a) This idea is intended to potentially benefit from the visual improvement of a standard headspan

but to try and introduce some improved performance /reliability. This idea can be applied to other

structures as well. To mix structures may well make the visual amenity worse. There is the

potential to compromise consistency, lines and worsen clutter.

b) The mix of solutions is viewed therefore to have a negative effect. In addition, there will also be

issues remaining regarding performance. As such it is recommended that this option is not

progressed.

9.5 Alternative Headspan Designs

a) Rigid Headspan. The idea is that the system contains a hybrid of wires and rigid members to

stabilise the geometry in the event of a single component failure.

b) This is likely to be more difficult to construct than some of the other structural solutions. There is

a requirement for getting the construction sequence including getting tensions in wires correct.

An advantage of a portal structure in this instance is that once erected, the structure can be left

until the small parts steel and wire are erected. With primarily a tensile structure all this work may

be required at the same time. Such an approach would also have to deal with up lift forces and

the risk of introducing resonant frequencies into the system. This has the potential to increase

wear and tear on the system thus increasing maintenance and decreasing reliability.

9.6 Improved Aesthetic Shape

a) Use of “more beautiful Sections” is very similar to the rigid headspan concept but with a profiled

boom. Technically, there should be no difference so from a technical evaluation it is assessed

the same.

9.7 Portal Structure – Radius (curved)

a) There should be no major issues in designing such a structure. Portal structures with curved

sections have been used elsewhere .e.g. on motorways. The viaduct portals can be considered

as broadly similar to a curved structure.

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9.8 Braced Structure

a) A braced structure is technically achievable. Such a structure will be more complex and have

more failure modes and a different inspection regime. The inspection regime would have to be

developed around the potential failure modes or the components making up the structure.

b) The foundations for such a structure would require a bespoke design and consequently the

existing foundation may not be suitable to reuse.

9.9 Viaduct back to back TTC’s/Portal

a) The designs for the Moulsford and Gatehampton Viaducts consisting of Portal and Back to

Back TTC have already been designed and are therefore compliant with the functional

requirements and there is no reason to indicate that there would be any reliability issues.

b) The back to back TTC may not be suitable for the geometry due to the introduction of posts

within the ten foot – this would require disruptive and time consuming additional foundations and

there could be issues with signal sighting as a result of the mast obscuring signal sighting

distances especially on curves – however this does not rule out the solution.

c) The Portal structure is likely to be a relatively easy replacement for the Series 1 portal if

appropriate.

d) There are also additional benefits with these solutions:

They are already being used on the viaduct with the portals on the approaches to the

viaducts. Continuation with Portals would maintain a consistent visual scene.

They have already been designed and therefore their introduction would be relatively quick

and there should be no function or reliability concerns.

No additional issues with spares requirements that could be generated with the introduction of

a completely new design.

The distance between the masts on the TTC are dictated by the distance between parapets

on the existing structures, there is therefore the possibility to reduce this distance. In areas

where there are not these existing structures constraints.

e) There are drawbacks to be considered with this solution, for example the 10ft is a likely place for

track drainage, additional cables and cable routes can be a problem. The structures do not

facilitate ALO working or high output. The consequences of two piles so close together need to

be considered. These structures are specific to location. Should any item need replacement it

would need to be specifically ordered.

9.10 Green Bridges

a) One specific option identified was the use of green bridges to mask the visual intrusion at specific

locations. Some initial evaluation has been made, however, as with the other landscape based

options; the potential of this as a solution will be considered fully in the LVIA exercise.

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Discussions to date with the Landscape Architect suggest that this option will not offer any

benefits.

b) Green Bridges are disruptive to local life during the construction phase.

9.11 Landscape Based Mitigation

a) Until a full assessment has been undertaken on the impact on the landscapes and the locations

and viewpoints of the sensitive receptors, it will not be possible to evaluate their potential benefit.

These are considered as complementary solutions that will be reviewed once the context of the

landscape is understood. This will be achieved by undertaking a Landscape and Visual Impact

Assessment (LVIA).

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10. The Toolbox Approach

a) A range of options are available to Network Rail to improve visual amenity. A potential approach

is illustrated in figure 12.

Options to Improve Visual Amenity of Electrification

Possible Package

of Options

LVIA

Mitigations

Change to an

existing Approved

System

New Design

Example

Moulsford Viaduct

Gatehampton Viaduct

Examples

Establish Vegetation

Use Structures & or tress to obscure views

Intervening Screening

Screening

Colour

Upgrade an

existing approved

design

Example

Headspan

Cantilever

Portal

Examples

RSSB Competition Entries

BB suggested designs.

Start End

Single Option

Or a range of

Mitigations

executed

LVIA

AONB & its Landscape

Characteristic

Assessments

1

3

2b

Amend Standard

Design

Examples

Lower ATF/Earth wires

Relocate ATF to ground level

Replace portal with cantilever

Use existing catalogue to best effect2a

2c

FIGURE 12 TOOLBOX APPROACH

b) This figure captures the lessons learnt in this project to date. It has become apparent that there

are a range of options (or toolbox) available for NR to consider. This is useful as it has become

apparent that there is unlikely to be a “one size fits” all solution for every landscape area.

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11. Selection Criteria

a) It is beyond this Phase to determine what options will be developed and implemented. However

the work done to date suggests some form of model will be required to assist NR in deciding

what, if any option or combination of options to proceed with. Figure 13 illustrates the main

elements of the decision making process. Dis-benefits has purposely not been defined here but

could mean cost, disruption or an increase in programme.

Increasing Visual Amenity

Dis

-be

ne

fits

Dis-benefits

Decreasing

Visual impact

As Is Option BOption A

FIGURE 13 MODEL FOR OPTION ADOPTION

b) In the AONBs each landscape or setting will lie somewhere on visual impact curve, sloping down

to the right. We don’t necessary know where on the curve that landscape is and it will to some

extent be a qualitative assessment.

c) The objective of any option will be to move the “as is” line to the right increasing visual amenity

and decreasing visual impact. To move the “as is” right will incur some dis-benefits. These dis-

benefits have not been fully defined but may include such items as, increased costs, delay to

programme and consequential delay to environmental and economic benefits.

d) In developing a system the whole life cost of the OLE has to be taken into account. Network Rail

have standard approaches and models for this. Whilst not considered for this phase it is noted

that greater cost consideration will be required in the next. Network Rail has a duty to minimise

costs to the government whilst benefits are maximised. The whole life cost models they use

support this objective.

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e) Elements in a Whole Life Cost include;

Operation Characteristics. As well as the initial service, the growth in the frequency of

service due to the introduction of electrification is assumed.

Time Series Characteristics consider the value of money over time, the inflation rate and

the year for calculation purposes and the construction year.

Design Cost includes any necessary product approvals as well as survey and the

construction detailed designs.

Labour Plant and Material Cost is essentially the construction cost and includes, planning

and organising of the work.

Disruption Cost is the cost of failure affecting the planned service or operation

characteristics. This can be estimated or assessed on previous experience and

understanding of failure modes.

Maintenance Cost is a function of the maintenance input required to maintain the system

this will include for example access constraints and specialist plant.

Renewal Cost includes the need to replace components or sub systems as they reach the

end of their life.

f) There are significant issues over the life of an OLE system to be considered if the optimum

solution is obtained. There may be compromises to be made for example the lowest design cost

may incur the greatest disruption cost.

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12. Options Recommended for further development

a) The options recommended for further investigation are described below. The images refer to 4

track sections but the options will be considered where appropriate for twin track sections.

12.1 Series 1 Amended

FIGURE 14 SERIES 1 AMENDED

b) Relocating the ATF is emerging through the LVIA work as a significant option for improving visual

amenity. In some cuttings it potential to make the railway no more visible than it was before (e.g.

Cotwolds North, noted this is two track railway with cantilevers.) electrification.

c) Included with this option is the possibility of shortening the mast height to the top of the boom.

d) It is also recommended that the Series 1 lattice form is revisited to create a less visible

alternative. Factors to explore are shallow depth, use of smaller struts and colour. Replacement

on a live railway would be considered as well as reuse of existing masts.

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12.2 Viaduct portal

a) The viaduct portal is broadly similar to the more graceful and curved structures. It can therefore

be seen almost as a sub set of those. If the small parts steelwork remains as Series 1 there are

no significant issues in designing and getting approval for a portal structure.

FIGURE 15 VIADUCT PORTAL

b) Adoption of this option has a number of advantages. Consistency of form along the route is one

and approval has already been obtained.

c) The structure can be amended for two track sections and can be designed to cater for ATF and

earth wire if required.

d) The centrelines of the middle tracks are approximately 8m apart where these have been installed

on the viaduct. The boom is approximately 25m long. There may be potential to reduce this

distance on the 4 track sections and reuse the existing foundations in specific circumstances.

These distances are fixed by the existing structures.

e) It should be noted Figure 15 is a cross section. A high level of accuracy has to be obtained for

these structures through all survey design and build stages. Accuracy for these structures starts

in fabrication and any error may end up in the structure returned to be refabricated.

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12.3 Viaduct Twin T

FIGURE 16 VIADUCT TWIN T

a) Adoption of this option has a number of advantages. Consistency of form along the route is one

and approval has already been obtained. The structure can be designed to cater for ATF and

earth wire if not at ground level.

b) The centrelines of the middle tracks are approximately 8m apart. The distance between the

outside faces of the columns is approximately 1.8m and is probably a function of the distance

between the parapets. There may be potential to reduce this distance on the 4 track section.

Although signal sighting and as built track separation may prevent this. There is also the potential

to reduce the length of the boom.

c) This structure may in some locations introduce signal sighting issues. It is theoretically possible

that a two track version could be designed but track geometry, location of drainage or cable may

render this impractical.

Anchor Structures

a) It is recommended that the options described above are also investigated to determine the

structural practicality of using them as anchor structures. This would be in terms of sizing of

members to determine minimum sections possible. Given the loads and the Series 1 components

the anchor structures must cater for there will be limited options for redesigning them.

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12.4 ATF Options

a) The ATF and indeed the earth wire can be relocated, either by installing it in cable troughs at

ground level or with difficulty lower on the masts. This has been done in tunnels, through bridges

and platforms. It has also been done where the ATF system is being retrospectively fitted on the

East Coast Mainline.

b) The ATF is fixed at heights of 8m or more on the masts. This is to achieve a number of

clearances under a number of conditions. The minimum distance from the ground in all

conditions is 5.2m. The ATF will in certain condition be tensioned e.g. the maximum tension at -

20oC on a 40m span is 16kn. Electro-magnetic fields around the contact and AFT cables tend to

cancel each other out to reduce interference.

c) Relocating ATF (& potentially earth wire) to Ground level offer the following visual amenity

advantages;

Consistency

o Fewer wires with more consistent lines

Simplicity

o Fewer wires

Ability to minimise overall height

o Mast height can be reduced

Minimise clutter

o Can remove insulators and gibbet effect

d) Lowering the ATF on the masts has the potential to make them invisible in certain locations. The

clearance requirements however will still apply.

e) Tensioning the ATF with a Tensorex type device creates a potential 3m height saving possible

on the masts. The tensioning effect will also create lines more consistent with the catenary and

contact wires. The following visual advantages may be obtained.

Consistency

Simplicity

Ability to minimise overall height

Minimise clutter

f) Some design and development would be required before such a system is available. From the

construction point of view relocating the ATF is not easy and will have generic and site specific

risks.

12.5 Landscape Based Mitigation

a) Landscape mitigation can be considered to include the use of new or established vegetation to

screen or obscure the OLE from certain perspectives. It is anticipated that these may emerge as

options in certain locations.

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12.6 Colour and Surface Finishes

a) The use of colour and surface finish to mitigate the visual impact of a structure is well established

from a number of perspectives. The finished colour of the larger elements (posts, beams, sub-

stations, fences) may benefit from being a more neutral colour than galvanised steel. Solutions

would be context-specific and should also take account of maintenance implications. Colour

treatment should have regard to the range of possible viewpoints of structures. The following

pictures illustrate where colour has been used in a landscape of higher sensitivity.

FIGURE 17 UNTREATED STRUCTURES JUST BEFORE TIBSHELF SERVICES M1

FIGURE 18 STRUCTURES TREATED BY HARDWICK HALL AND ESTATE

b) In figure 18 the structures have been modified from the regular grey colour to a light brown (BS

4800 colour ref 08 C 39). In the distance a grey gantry can be made out. There is a light brown

gantry before this.

FIGURE 19 WOODEN TELEGRAPH POLE OBSCURING A MAST

c) In figure 19 a wooden telegraph pole, circled in red, obscures a mast of a portal structure. This

illustrates a potential mitigation through a sensitive choice of colour.

d) It has been recommended that an Environmental Colour Assessment is made in wintertime to

determine the optimum colour for specific locations in the AoNBs.

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13. Concluding Remarks

a) The project to date has shown there is unlikely to be a simple “silver bullet” solution. By silver

bullet we mean a standard structure that can be installed in any landscape setting and improve

the visual amenity. Each AONB is by definition unique and a bespoke structure in one might not

be optimal in another.

b) A structure viewed from one perspective may be more acceptable than the same structure

viewed from a different position.

c) There is a range of options (or Toolbox) that can be developed and applied to improve Visual

Amenity. Adopting or developing such a concept may offer the optimum solution to Network Rail

and their stakeholders.

d) There is no method currently available to model the relationships between costs and benefits of

implementing an improvement to Visual Amenity.

e) The railway and the AONBs will be entwined for generations. This fact provides the opportunity to

ensure long term solutions such as use of vegetation are available.

f) The difficulties of retrofitting, amending or building a new structure on an operational electrified

railway are significant and this report has highlighted the high level implications. It is likely that as

an option is developed more specific risk and hazards will come to light.

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14. Appendices

The following appendices are included in this report.

Appendix Description

Appendix 1 Basic Visualisations of Options

Appendix 2 Assessment of Options

Appendix 3 RSSB Competition for Aesthetic OLE

Appendix 4 Moulsford and Gatehampton Solution

Appendix 5 Project Hazard & Risk Log

Appendix 6 Log of Issues from Advisory group

Appendix 7 GWEP Visual Amenity Glossary

Appendix 8 Headspans

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Balfour Beatty Rail