Second Avon Crossing Transport Modelling

TECHNICAL MEMORANDUM

PREPARED FOR: Bristol City Council

DATE: December 5th, 2016

PROJECT NUMBER: 673846.AO.14.01

STATUS: Final

WRITTEN BY: Toufik Al-Joura / Chris Bushell

APPROVED BY: Chris Bushell

1.0 Introduction 1.1 Overview CH2M have been commissioned by Bristol City Council (BCC) to undertake transport modelling and cost benefit analysis associated with two potential alignments for a second bridge crossing of the river Avon, in the vicinity of the existing M5 crossing. The new crossing is referred to as the Second Avon Crossing (SAC). 2.0 Scheme Assumptions 2.1 Options AECOM have been commissioned to undertake a feasibility study for various SAC options. This has identified possible options as shown in Figure 1. As advised by BCC, the options assessed by CH2M are Options 1 and 31. 2.2 Design assumptions In each option the SAC has been assumed to have one lane per direction. Due to the preliminary stage of option development, junction designs have not yet been produced for locations where the SAC will interact with the existing road network. Hence assumptions have been agreed with BCC / AECOM relating to the form of junction at each relevant location. Further, junctions have been coded on the basis that it is assumed sufficient capacities will be incorporated into junction designs to accommodate SAC traffic volumes. Table 1 indicates the assumed junction forms at relevant locations.

A4 Portway A369 Gordano Way Victoria Rd Marsh Ln Option 1 Signal Signal N/A N/A No connection Option 3 Signal N/A Priority N/A roundabout Table 1 – Assumed Junction Types

1 Option 3 includes the part of Option 2 over the River Avon to connect to the A4 Portway

1 SECOND AVON CROSSING TRANSPORT MODELLING

Figure 1 – SAC Options identified in AECOM study 2.3 Scheme Costs Costs for each option have been provided by AECOM. A further nominal allowance of 5% has been made for land and operating / maintenance costs over the assessment period (60 years). 44% Optimism bias has been applied in accordance with DfT guidance, in addition to 15% risk / contingency. Since AECOM have included an inflation allowance of 12.6% from the time of cost estimation (2016) until mid construction (2019), costs have been adjusted so as only to include cost increases in real terms (i.e. excluding general inflation, as advised by TAG). This has resulted in a net cost decrease of around 6% based on the GDP deflator, as per the WebTAG Databook (July 2016). Table 2 shows the costs for each option (2016 £ values and prices).

2 SECOND AVON CROSSING TRANSPORT MODELLING

Option 1 Option 3 Base costs 147,192,679 159,429,600 Operating cost 3,679,817 3,985,740 Land 3,679,817 3,985,740 Optimism bias 68,003,018 73,656,475 Total 222,555,330 241,057,555 Table 2 – Scheme Costs 3.0 Methodology 3.1 Overview The GBATS4M transport model of the Greater Bristol area has been used to test the SAC options. Scenarios have been modelled in the AM peak, inter-peak (IP) and PM peak models with forecast years of 2021 and 2036. This model contains assumptions about planned developments and schemes within the model area, in accordance with DfT guidance. Table 3 details the total additional homes/jobs explicitly assumed in the future year Reference Case models (excluding smaller sites less than 1 hectare for employment sites less than 50 homes for housing). The forecasts are also controlled to Tempro growth in line with DfT guidance. Car trips are forecast to increase by around 20% by 2036.

Year Additional New Homes Additional New Jobs

2013-2021 27,719 34,621

2021-2036 7,656 16,937

2013- 2036 35,375 51,559 Table 3 - Additional Planned Development included in Do Minimum

Further information on the model development is contained in GBATS4M MetroWest Do Minimum Forecasting Report, February 2016. To identify monetary impacts, TUBA2 software was used which incorporates the DfT’s Transport Appraisal Guidance (TAG) economic parameters issued in December 2015. 3.2 Transport Modelling To assess the new crossing options, the relevant highway links and connections were coded into the modelled network. The model was then re-assigned using a fixed demand highway assignment. Checks have been undertaken to ensure that local capacity constraints do not unduly limit the operation of the SAC in the model runs undertaken. No bus routes have been altered in the assessment. 3.3 Monetary Impacts Monetary impacts have been identified over a 60 year appraisal period using the DfT TUBA software in line with DfT guidance. Expansion factors were applied based on local data to calculate peak period and inter-peak period impacts from the modelled hours as follows:

2 Transport User Benefits Assessment version 1.9.6

3 SECOND AVON CROSSING TRANSPORT MODELLING

 AM : 2.55  IP : 6  PM : 2.56

Further expansion to annual impacts were derived assuming 253 weekdays per year.

TUBA uses value of time (VOT) parameters in line with DfT guidance which vary by trip purpose and traveller income group. Car driver 2015 values are as follows:

 Employers’ business: £26.54 / hour  Non-work low income: £5.31 / hour  Non-work medium income: £6.76 / hour  Non-work high income: £8.54 / hour

Appendix A gives further details of the TUBA guidance ‘consumer surplus’ calculations which have been employed. 4.0 Scheme Assessment 4.1 Traffic flows Table 4 provides the 2036 forecast traffic flows on the SAC for each option assessed in terms of passenger car units (PCUs) per hour. The modelling assignments indicate that 80-90% of the trips to use the new crossing would be diverted from the existing M5 crossing, with the remainder drawn from other routes. Option 1 Option 3 AM IP PM AM IP PM Eastbound 431 205 278 424 276 374 Westbound 539 327 751 691 384 878 Total 970 532 1029 1115 660 1252 Table 4 - SAC Traffic Volumes (PCUs)

This shows that SAC flows for Option 3 are slightly higher than those for Option 1 by around 15 to 20%. Table 5 provides modelled traffic flows for the M5 Avon crossing as a comparison, for each option post- construction of the new crossing. This indicates that the SAC is forecast to carry up to around 10% of the corresponding M5 volumes in the peak hours and around 5% in the inter-peak hours. Option 1 Option 3 AM IP PM AM IP PM Eastbound 6404 5148 5517 6445 5081 5456 Westbound 4701 4860 5945 4632 4844 5836 Total 11105 10008 11462 11077 9925 11292 Table 5 - M5 Traffic Volumes (PCUs) 4.2 Cost Benefit Analysis Table 6 gives the results of the cost benefit analysis, as per section 3.3.and Appendix A, reflecting re- routing of trips and associated reduced journey times and distances in aggregate across the network. Monetary values are presented in 2010 prices and values as per DfT guidance.

4 SECOND AVON CROSSING TRANSPORT MODELLING

Option 1 Option 3 Present Value of Benefits (PVB) 70,867,023 83,937,082 Present Value of Costs (PVC) 148,101,136 160,414,495 Net Present Value (NPV) - 77,234,113 - 76,477,413 Benefit Cost ratio (BCR) 0.48 0.52 Table 6 - Cost Benefit Analysis

The CBA results indicate that whilst Option 3 performs slightly better than Option 1, both options yield a low BCR value due to limited benefits relative to the scheme costs. It should be noted that the SAC may offer network resilience benefits, e.g. as an alternative route during incidents on the M5, which are not represented in this assessment. 5.0 Limitations 5.1 Overview It is advised that the assessment undertaken is a preliminary assessment to identify the broad level of benefits expected from the SAC. This has been undertaken using the GBATS4M highway model which was not developed specifically for the assessment of this scheme. The scheme assessment is potentially sensitive to the trip composition of users of the M5 crossing, particularly in relation to the mix of local verses long distance trips.

Further tasks that have not been undertaken, but would be recommended for a more detailed assessment, include:  ANPR survey (or similar) to gauge local traffic levels using M5 bridge  select link analysis of modelled M5 traffic  adjustment of model to reflect local / strategic traffic mix on M5 bridge by vehicle type  check of M5 bridge volumes against data and adjustment for significant differences  check of nearby M5 junction volumes against data and adjustment for significant differences  junction assessments of affected local junctions used for SAC access, such as M5 J19, A4 Portway etc.  review of highway network performance and constraints, and further potential network optimisation / enhancements  analysis of SAC users  analysis of scheme benefits, including spatial disaggregation  assessment of network resilience benefits, such as scheme benefits if M5 closures / restrictions occur, accounting for expected incident frequency. 6.0 Conclusions 6.1 Results The assessment above indicates that the SAC would carry around 10% of the corresponding M5 volumes in the peak hours and around 5% in the inter-peak hours. Option 3 is forecast to carry slightly higher volumes than Option 1. The modelling assignments indicate that 80-90% of the trips to use the new crossing would be diverted from the existing M5 crossing, with the remainder drawn from other routes.

The cost benefit analysis undertaken indicates BCRs are relatively low for both options considered, at 0.48 and 0.52 for Options 1 and 3 respectively. These values have been calculated as per section 3.3.and

5 SECOND AVON CROSSING TRANSPORT MODELLING Appendix A, reflecting re-routing of trips and reduced journey times and trip distances in aggregate across the network. 6.2 Limitations Due to the preliminary nature of the assessment, further refinement could be undertaken to improve the accuracy of the modelling and CBA results, as indicated above. Improved local connectivity / ambience for pedestrians and cyclists has not been included in this assessment. The scheme would offer a more direct crossing from the Shirehampton area for non- motorised users and offer a quieter route compared to the existing path alongside on the M5, with associated potential health benefits. However, taking these factors into account would be quite sensitive to subjective assumptions and unlikely to materially change the BCR. To undertake an assessment of this a count of the number of current non-motorised users of the M5 bridge would be helpful to understand current usage.

6 APPENDIX A – TUBA CALCULATIONS Appendix A – TUBA Calculations

Second Avon Crossing (2AC)

High-level Engineering Feasibility Study to inform Joint Transport Strategy

January 2017

Prepared for Bristol City Council

Issue Date Details Prepared by Checked by Approved by

1 17/06/16 Draft for interim client review Stuart Evans Christos Ted Evans Christodoulou Associate Director Regional Director James Gundy Ted Evans Jason Drummond

2 08/07/16 Draft Stuart Evans Christos Ted Evans Christodoulou Associate Director Regional Director James Gundy Ted Evans Jason Drummond

3 07/11/16 Draft 2 for client comment Stuart Evans David Dales Ted Evans Associate Director Technical Regional Director Reviewer Jason Drummond Principal Flood and Coastal Specialist

4 17/01/17 Final Jason David Dales Ted Evans Drummond Technical Regional Director Principal Flood Reviewer and Coastal Specialist

AECOM ONE Callaghan Square Cardiff Wales CF10 5BT

Limitations AECOM Infrastructure & Environment UK Limited (“AECOM”) has prepared this Report for the sole use of Bristol City Council (“Client”) in accordance with the Agreement under which our services were performed River Avon Tidal Flood Risk Management Strategy RESP1007626 (23/10/15) and Response to Tender Submission Clarifications (03/11/15) (the “Agreement”). The report takes into account the particular instructions and requirements of the Client in accordance with the provisions of the Agreement. It is not intended for and cannot be relied upon by any third party. No liability is accepted by AECOM and no responsibility is undertaken to any third party. Information obtained by AECOM has not been independently verified by AECOM, unless otherwise stated in the Report. The methodology adopted and the sources of information used by AECOM in providing its services are outlined in this Report. The work described in this Report was undertaken between May 2016 and January 2017 and is based on the conditions encountered and the information available during the said period of time. The scope of this Report and the services are accordingly factually limited by these circumstances. Where assessments of works or costs identified in this Report are made, such assessments are based upon the information available at the time and where appropriate are subject to further investigations or information which may become available. Copyright © This Report is the copyright of AECOM Infrastructure & Environment UK Limited. Any unauthorised reproduction or usage by any person other than the addressee is strictly prohibited.

TABLE OF CONTENTS

1. INTRODUCTION AND METHODOLOGY ...... 1

2. EXISTING CONSTRAINTS ...... 1

3. DESCRIPTION OF OPTIONS ...... 2

4. HIGHWAY ALIGNMENT ASSESSMENT ...... 5

5. ENVIRONMENTAL CONSTRAINTS ...... 7

6. ENGINEERING ASSESSMENT - STRUCTURES ...... 11

7. INTERFACE WITH TIDAL FLOOD RISK MANAGEMENT STRATEGY ...... 14

8. TRANSPORT CONNECTIVITY ...... 15

9. COST ESTIMATES ...... 16

10. ASSESSMENT OF OPTIONS ...... 19

11. CONCLUSIONS AND RECOMMENDATIONS ...... 22

A VERTICAL ALIGNMENTS ...... 24

B CONCEPT DESIGN SKETCHES ...... 25

C OPTION COST ESTIMATES ...... 26

1. INTRODUCTION AND METHODOLOGY

Background Bristol City Council (BCC) wishes to commission a high level feasibility study for the provision of a Second Avon Crossing (2AC) near to the existing M5 crossing. The study will focus on the technical, environmental, engineering and cost/benefit issues. The outcome will be a view as to whether the 2AC should be progressed further and in more detail in the Joint Transport Study (JTS) being carried out by the West of England. The feasibility study will seek to define any critical items or “showstoppers”. The key considerations of the study are as follows:- 1. Technical feasibility of a Second Avon Crossing (2AC) and suggested alignment, and any ‘showstoppers’. 2. Discussion of the engineering challenges posed and what solutions might be required to overcome them if they can be overcome. 3. Review of the access routes to connect Portishead to the South and Avonmouth to the North and links to the existing transport infrastructure. The 2AC route will also need to support the integrity of the area network. 4. A high level overview of elements such as clearances (fixed or moving central spans), location of supports, geotechnical conditions, form of structure etc. 5. Based on the aforementioned points the primary requirement will be to define the most economically viable engineering solution to provide the required transport linkages, maintain existing navigation rights and minimise environmental and flood risk. 6. Approximate initial costs of a 2AC as a standalone build and consideration of potential joint build cost from the construction of a potential tidal flood barrier. 7. Investigation into the environmental challenges are posed by the alignment. 8. How a 2AC could be integrated into the wider road network.

Methodology Our detailed methodology is described below:- 1. We have undertaken a desk based review of existing information, studies, reports and mapping to establish the baseline for the study and define the limitations of the current information, making best use of work completed to date on the AECOM Tidal Flood Risk Management Study (TFRMS). 2. We have worked up a short list of potential options which seek to address the issues. 3. We have assessed the options against the engineering viability, deliverability and environmental considerations.

Study Area The boundaries of the feasibility study area are defined on the Ordnance Survey Extract Figure 1.

2AC – HIGH LEVEL ENGINEERING FEASIBILITY STUDY

349000 350000 351000 352000 353000 354000 355000

AECOM Limited 1 Callaghan Square

179000 Cardiff, CF10 5BT +44 (0)29 2067 4600 tel www.aecom.com Project Title:

SECOND AVON CROSSING OPTIONS

Client: 178000 LEGEND Severn Beach Railway Line Study Area Boundary nt Gordano Motorway Services ^_ Rhyne/Lagoon n£ Portway Park and Ride M5 Motorway A369 A4 Railway n£ Railway Tunnel

177000 A4 Portway Royal Portbury Dock Railway Line

M5 Overbridge

SHIREHAMPTON Gordano Way / Royal Portbury Dock Rd ^_ Station Road Shirehampton

Portishead Railway Line Station Road Rail Underbridge 176000

Marsh Lane nt PILL

Martcombe Road

Projection: British National Grid

175000 Copyright: OS data © Crown copyright & database rights 2015 Ordnance Survey 100023406 AECOM Internal Project No: 60478613 Drawing Title:

SITE LOCATION PLAN

Scale at A3: 1:20,000 Drawing No: Rev: 174000 FIGURE 1 V1 0 125 250 M Source: Esri, DigitalGlobe, GeoEye, Earthstar Geographics, CNES/Airbus DS, USDA, USGS, AEX, Getmapping, Aerogrid, IGN, IGP, Drawn: Chk'd: App'd: Date:

swisstopo, and the GIS User Community ± This drawing hasbeen prepared for the useAECOM's of client. It maynot be used, modified, reproducedor relied upon bythird parties, except asagreed CCby AECOM or asrequired bylaw.AECOM accepts noresponsibility, anddenies anyliability whatsoever, to any party thatuses orrelies on thisdrawing withoutAECOM's express written consent. Donot scale this document.All measurements must beobtained from the stateddimensions. HS NT 03/11/16 Filename: P:\UKCDF1-IE\Projects\!GIS Management\001 Projects\River Avon Tidal Flood Risk\02_Maps\SecondAvonCrossing_1_LocationPlan_2ACReport.mxd

2. EXISTING CONSTRAINTS

The following features are a list of engineering and environmental constraints which will influence the alignment of the proposed 2AC as shown in Figure 2.

1. A4 Portway. The highway connection tie in in terms of level, proximity to other junctions and proposed junction form will be considered.

2. Park and Ride Site. The effects on the existing facility and its access will be considered.

3. Severn Beach Railway Line (live) – the need to maintain Network Rail’s headroom requirements.

4. Rail Line to Portbury Docks which is currently used. Minimum headroom as advised by BCC is 7.2m rail level to soffit level. Portishead Railway Line which is currently used as a link to the dock and therefore live for the purposes of this report. Minimum headroom as advised by BCC is 7.2m rail level to soffit level. This is in line with the requirements of the proposed Metrowest rail upgrade.

5. There are a number of designated sites within the Study Area. These include the Severn Estuary Site of Special Scientific Interest (SSSI), Ramsar Site and Special Protection Area (SPA). These areas include both banks of the River Avon. These will influence the structural form, pier spacing and earthworks. If any habitat loss is incurred then BCC may want (or need) to consider compensatory habitat provided in an alternative location. It is recommended that any additional habitat loss should be calculated at an early stage of the project so that appropriate mitigation can be sought and agreed with the competent authorities and statutory stakeholders.

6. River Avon (tidal).The TFRMS study has indicated a 1:1000 year design water level of 10.9m AOD in the Shirehampton/Pill area for a tidal barrier structure. This includes 0.3m freeboard and uses a conservative climate change scenario. A 1m freeboard to bridge soffit has been allowed to cater for floating debris.

7. The navigation clearances have been determined from Client supplied data (referencing work carried out by Atkins), namely clear opening of 20m width and a vertical clearance of 10m at the high water mark.

8. The high water mark has been determined by the AECOM TFRMS study as the 1:1000 year design water level of 10.9m AOD in the Shirehampton/Pill area. This includes 300mm freeboard and uses a conservative climate change scenario.

9. Existing Housing at Lodway and Pill. The alignment of the 2AC may require land acquisition.

10. Local Road (Marsh Lane) from Easton–in-Gordano to Portishead. A decision on whether to tie in at grade or bridge over will need to be made.

11. There is a Wessex Water outfall at Lamplighters Marsh, which may need clearance for future maintenance/replacement. This is not considered to be a significant issue but one to be addressed as part of the detailed design should it be within the selected route corridor.

12. M5 overbridge. The existing headroom and location of piers will influence the alignment of the 2AC.

13. Gordano Motorway Services. The potential to impact on the Services will need to be considered.

14. A369 Martcombe Road. The level of the existing highway and junction form will be a key consideration.

15. Existing Government Oil Pipeline. The existing safeguarding easements will need to be maintained.

16. Existing overhead electrical cables. The existing safeguarding easements will need to be maintained.

2AC – HIGH LEVEL ENGINEERING FEASIBILITY STUDY

17. Existing Industrial & commercial premises including car storage areas. The potential to acquire land will need to be considered.

18. Existing rhyne/ lagoon between car storage areas will need to be considered in terms of environmental impact.

19. Existing National Cycle Route no. 26 may need to negotiate or cross the 2AC.

20. Existing local long distance footpaths / public rights of way may need to negotiate or cross the 2AC.

The effects of the existing constraints are further analysed in Table 5 in Section 10.

2AC – HIGH LEVEL ENGINEERING FEASIBILITY STUDY

350000 351000 352000 353000 ^_ Severn Beach Railway Line

AECOM Limited 1 Callaghan Square Cardiff, CF10 5BT +44 (0)29 2067 4600 tel www.aecom.com Project Title:

SECOND AVON CROSSING OPTIONS

Client:

^_ ^_ LEGEND

^_ nt Gordano Motorway Services n£ ^_ ^_ Rhyne/Lagoon ^_ ^_ ^_ n£ Portway Park and Ride 177000 ^_ Grade I Listing ^_ ^_ A4 Portway ^_ ^_^_ ^_ Grade II Listing ^_ Grade II* Listing Royal Portbury Dock Railway Line M5 Overbridge ^_ ^_ M5 Motorway Option 4 ^_^_^_^_ A369 A4 Option 1 Railway Railway Tunnel ^_ National Cycle Route 26 Transportation Design Option 1 Transportation Design Option 2 Option 2 Transportation Design Option 3 Transportation Design Option 4 Option 3 Transportation Design Option 5 Gordano Way / Royal Portbury Dock Rd ^_ Option 5 Study Area Boundary Site of Special Scientific Interest - Environment Agency ^_^_^_ Special Protection Areas - Environment Station Road Shirehampton ^_ Agency Special Areas of Conservation - Environment Agency ^_ RAMSAR - Environment Agency Important Bird Areas - RSPB Lamplighters Marsh LNR ^_ Lamplighters Marsh SNCI Bridleway Portishead Railway Line ^_ Footpath Registered byway

176000 Station Road Rail Underbridge NCR 26 ^_ Cycle Network PILL ^_

Marsh Lane ^_ ^_ ^_ Projection: British National Grid ^_ Copyright: ^_ OS data © Crown copyright & database rights 2015 Ordnance nt Survey 100023406 AECOM Internal Project No: 60478613 ^_ Drawing Title: ^_ ^_^_ ^_ ^_^_ ENVIRONMENTAL ^_ CONSTRAINTS MAP

Scale at A3: 1:10,000 ^_ Martcombe Road ^_ ^_ Drawing No: Rev: FIGURE 2 V1 0 125 250 M Drawn: Chk'd: App'd: Date:

± This drawing hasbeen prepared for the useAECOM's of client. It maynot be used, modified, reproducedor relied upon bythird parties, except asagreed CCby AECOM or asrequired bylaw.AECOM accepts noresponsibility, anddenies anyliability whatsoever, to any party thatuses orrelies on thisdrawing withoutAECOM's express written consent. Donot scale this document.All measurements must beobtained from the stateddimensions. HS NT 03/11/16 Filename: P:\UKCDF1-IE\Projects\!GIS Management\001 Projects\River Avon Tidal Flood Risk\02_Maps\SecondAvonCrossing_2_Constraints_2ACReport.mxd

3. DESCRIPTION OF OPTIONS

Following a review of the existing constraints, available information and required objectives the following outline design options were developed as shown in Figure 3.

Available Information 1. Greater Bristol Strategic Transport Study (Atkins) 2. Maximum tide levels from TFRMS 3. Minimum headroom for disused rail lines from BCC 4. Minimum headroom for live rail line from Network Rail 5. Existing 3D LIDAR data 6. Existing Ordnance Survey mapping 7. Site reconnaissance photographs

Engineering Criteria The links are designed in accordance with the Design Manual for Roads and Bridges TD9/93 for a 50kph assumed design speed. Maximum gradients have been set at 5% and desirable minima for crest k=10 and sag k=9 curves applied. At this stage a 7.3m carriageway with a 3.5m cycleway and a 2.0m footway have been assumed for the 2AC cross section. A 1m verge and 1 in 3 earthwork slopes have also been assumed for the purposes of land take.

Potential for Barrier Synergy The primary purpose of this Second Avon Crossing (2AC) report is to provide an overview of the feasibility of a second highway crossing. A secondary order consideration for the 2AC study is to consider the potential for the highway crossing location being situated in a similar location under consideration for a tidal barrier and identifying any potential synergy that this could bring. The tidal barrier concept has been considered by the River Avon Tidal Flood Risk Management Strategy (TFRMS). At the time of writing, indicative locations for a possible barrier had been proposed to delineate between a "wide" and a "narrow" barrier (during the shortlisting phase for the TFRMS). The “wide” barrier location was between the Pill and Shirehampton areas, upstream of Option 2, but downstream of the river section of Option 5 (noting that the southern approach merges with the wide barrier location). The barrier would be perpendicular to the river and is in the 2AC study area. The narrow barrier location was situated several hundred metres further upstream of Option 5, and was referred to as the Nibley Road barrier (from the nearest street name in Shirehampton). The narrow terminology reflects the river’s reduced width compared to the wide barrier location. Like the wide barrier location, the narrow barrier concept is perpendicular to the river. The location is outside of the 2AC study area. From a transportation perspective, the Nibley Road barrier location would incur very difficult topographical challenges on the south side and increase journey times if the route was to act as relief to the M5. In that sense, the location is less attractive than the 2AC study area, and eliminates the potential for synergy with a barrier in this location. Therefore, none of the crossing options have synergy with the narrow barrier location. A non-perpendicular crossing alignment, as proposed for Option 5, reduces the potential for synergy with a tidal barrier because this would increase flow impedance. Similarly, if energy generation was also a consideration in the future, the structure would need to be optimised to the direction of maximum flow i.e. perpendicular. However, this option is in the assessment to inform the primary consideration of the identification of a potential crossing location which best meets the transportation requirements of the locality and the wider area access to employment areas.

2AC High Level Feasibility Report 2

The potential for synergy between Options 1-4, and primarily Option 2 is reported in Section 7. Options Overview Option 1 This Option joins the A4 Portway via a new junction and bisects the existing Park & ride site. The new junction may allow reconfiguration of the existing Park and Ride site. The link crosses the Severn Beach Rail Line on a road over rail bridge and then over the River Avon including its banks. The link then crosses the Portbury and Portishead Rail Lines on road over rail bridges before crossing Marsh Lane on a road over road bridge. Consideration could be given to an at grade junction at this location instead. Depending on the exact design of the link, between 2 and 4 houses will need to be acquired to accommodate the link. The link passes to the south east of Gordano Motorway Services before joining the A389 Martcombe Road at a new junction. Option 2 This Option joins the A4 Portway via a new junction to the west of the existing Park & ride site. The link crosses the Severn Beach Rail Line on a road over rail bridge and then over the River Avon including its banks. The link then crosses the Portbury and Portishead Rail Lines on road over rail bridges before joining the alignment of Option 1. Option 3 This Option joins Option 2 before it crosses the Portbury Rail Line and heads south west, crossing under the M5 overbridge. The link then bisects the existing car storage areas to the south of an existing rhyne / lagoon before joining the existing road network at Marsh Lane and Gordano Way. Option 4 This Option is the only one identified downstream of the M5 overbridge. It joins the local road network at Victoria Rd (industrial estate) but could, conceivably, with some local reconfiguration join the A4 Portway. The link crosses the river Avon and rises over the Portbury Rail Line via a road over rail bridge. It then joins Option 3 at the north end of the existing car storage area. Some land will be required from the car storage area to facilitate this link. Option 5 This Option is the furthest upstream identified. It joins the existing road network at Station Road Shirehampton. The exact tie point will depend on the vertical alignment to clear the Avon 1 in 1000 yrs tide level + freeboard. Land would need to be acquired from the yacht club to facilitate this link. Due to the narrow width of Station Road online widening would be required which could require land and property acquisition. The existing underbridge at the Severn Beach Line would require modification to provide a standard highway headroom. Currently it is signposted as only 11 feet 9 inches (3.6m). The link crosses the River Avon and its banks on a skewed alignment before rising up over the Portbury and Portishead Rail Lines on road over rail bridges. It then joins Option 1 alignment. These Options are interlinked and have been assessed insofar as the permitted combinations would be:  Option 1 – Complete Scheme  Option 1 & 2 – Option 1 to Portbury and Portishead rail lines followed by Option 2 to A4 Portway  Option 3 & 2 – Option 3 and the north eastern section of Option 2 over the Avon to the A4 Portway  Option 3 & 4 – Option 3 merging with the southern starting point of Option 4  Option 1 & 5 – Option 1 to Severn Beach railway crossing followed by Option 5 to A4 Portway

2AC High Level Feasibility Report 3

349000 350000 351000 352000 353000 354000 355000

AECOM Limited 1 Callaghan Square

179000 Cardiff, CF10 5BT +44 (0)29 2067 4600 tel www.aecom.com Project Title:

SECOND AVON CROSSING OPTIONS

Client: 178000 LEGEND Severn Beach Railway Line Study Area nt Gordano Motorway Services ^_ Rhyne/Lagoon n£ Portway Park and Ride M5 Motorway A369 A4 Railway n£ Railway Tunnel Transportation Design Option 1 177000 A4 Portway Transportation Design Option 2 Royal Portbury Dock Railway Line Option 4 Transportation Design Option 3

Option 1 Transportation Design Option 4 M5 Overbridge Transportation Design Option 5

Option 2

Option 3 SHIREHAMPTON Gordano Way / Royal Portbury Dock Rd ^_ Option 5 Station Road Shirehampton

Portishead Railway Line Station Road Rail Underbridge 176000

Marsh Lane nt PILL

Martcombe Road

Projection: British National Grid

175000 Copyright: OS data © Crown copyright & database rights 2015 Ordnance Survey 100023406 AECOM Internal Project No: 60478613 Drawing Title:

SITE LOCATION PLAN

Scale at A3: 1:20,000 Drawing No: Rev: 174000 FIGURE 3 V1 0 125 250 M Source: Esri, DigitalGlobe, GeoEye, Earthstar Geographics, CNES/Airbus DS, USDA, USGS, AEX, Getmapping, Aerogrid, IGN, IGP, Drawn: Chk'd: App'd: Date:

4. HIGHWAY ALIGNMENT ASSESSMENT

Horizontal Alignment

The key constraints to the horizontal alignment which affect the options are as follows:

1. North bank of the River Avon – existing housing, Park and Ride Site, M5 overbridge and the industrial site at Avonmouth. 2. The live railway lines which would ideally be crossed as square spans to simplify design and construction of structures and reduce costs. 3. The River Avon which would ideally be crossed as a square span to simplify design and construction and reduce costs. 4. South bank of the River Avon - existing road, Marsh Lane, which would ideally be crossed as a square span to simplify design and construction and reduce costs. 5. South Bank of the River Avon – existing housing (Lodway & Pill) and the Gordano Services. 6. Existing overhead power cables 7. Existing banks of the River Avon (Ramsar/SAC/SPA/SSSI). 8. Existing rhyne/ lagoon between car storage areas. 9. Existing A369 Martcombe Road. 10. Existing Station Road at Shirehampton. Vertical Alignment The key constraints to the vertical alignment are as follows:- 1. Tie in levels to the A4 Portway. 2. Tie in levels to Station Road. 3. Headroom under existing Severn Beach bridge at Station Road. 4. Headroom clearance over the Severn Beach Railway Line. 5. Headroom Clearance over the Portishead and Portbury Docks Railway Lines. 6. Headroom Clearance over Marsh lane or tie in at grade. 7. Headroom clearance under the M5 overbridge. 8. Clearance cover existing pipelines. 9. Clearance under existing overhead power lines. 10. Tie in levels to the A369 Martcombe Road. 11. Tie in Levels to the existing Marsh Lane downstream of the M5. 12. Tie in levels to Gordano Way / Royal Portbury Dock Road Roundabout.

Junctions with Existing Highway Network

At this early stage the following junction forms are suggested but would need more detailed traffic modelling and design input to confirm their suitability as the project progresses. Table 1 describes the potential junction options.

2AC High Level Feasibility Report 5

Table 1 – Potential Junction Options to Existing Network

Gordano Victoria Marsh Ln East Marsh Lane A4 Portway A369 Way Rd of M5 West of M5 Option Traffic Signal N/A N/A N/A 1 Signal or No connection if Roundabout overbridge or roundabout Option Traffic Signal Priority N/A Roundabout 2 Signal or No connection if Roundabout overbridge or roundabout Option Traffic Signal N/A Priority N/A N/A Roundabout 3 Option N/A Priority N/A Roundabout 4 Existing Changed junction may priority T need to be Junction upgraded to accommodate traffic volumes Option N/A N/A N/A 5 Existing Signal or No connection if junction may Roundabout overbridge or need to be roundabout upgraded to accommodate traffic volumes

Outline preliminary vertical alignments have been developed to define the principal elements and geometry, details of each vertical alignment is contained in Figure 3 in Appendix A.

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5. ENVIRONMENTAL CONSTRAINTS

The main environmental constraints which exist within the study area are presented in Table 2 below. Measures which should / could be considered to mitigate any adverse impacts are also identified. See Figure 4 for a map showing the environmental constraints within the Study Area.

Our assessment finds that there are no showstopper environmental constraints, which are immitigable. However, if the crossing is progressed there will be a considerable amount of environmental (impact) assessment work to be completed to identify and mitigate impacts. Table 2 - Environmental Constraints

Environmental Receptors and Potential Impacts Proposed Mitigation Constraints

Ecology All option alignments are located in close proximity to A Water Framework Directive (WFD) the Severn Estuary, which is designated as a Special Assessment is likely to be required. Due Protection Area (SPA) designated under the Birds to the nature, size and proximity of the Directive, and Special Area of Conservation (SAC) proposed alignments to an designated under the Habitats Directive. The SAC internationally designated site this may incorporates the River Avon whilst the SPA necessitate an Environmental Impact incorporates the River Avon mudflats. Both Habitats Assessment (EIA) as well as a Habitats Directive Sites and Birds Directive Sites form part of Regulations Assessment (HRA) Likely the Natura 2000 network of sites In addition, the River Significant Effects Screening, which Avon is designated as a Ramsar Site, Special Site of may have programme and cost Scientific Interest (SSSI) and an Important Bird Area implications. (IBA) according to RSPB data. If any of the alignments are developed The Study Area also includes Lamplighters Marsh Site within a Natura 2000 site, which applies of Nature Conservation Interest (SNCI) and to Option 1, 2, 4 and 5 crossings, the Lamplighters Marsh Local Nature Reserve (LNR) which Imperative Reasons of Overriding Public are both designated for their local importance. Importance (IROPI) aspect of the Habitats Regulations is likely to be There may be a negative impact on these designated triggered. An application to the sites which are in close proximity to the option Secretary of State will be required and alignments, particularly during the construction phase compensatory habitat provision will be due to increased levels of disturbance associated with required under the Regulations. This construction activity. would have significant financial and additional work implications.

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Environmental Receptors and Potential Impacts Proposed Mitigation Constraints

Archaeology Within the Study Area there is one Grade I Listed Any negative effects can potentially be and Built Building which is the Church of St Mary in Portbury, mitigated by careful design and siting of Heritage and eleven Grade II Listed Buildings, which include: the option alignment away from sensitive heritage assets and previously  The Lamplighters Public House recorded archaeological deposits to  Wellington House and attached stables reduce any environmental impact. The  105 Station Road form, layout and orientation of the option alignment should be developed  103 Station Road to limit any impacts to the setting of  Watch house, retaining walls to the river and garage heritage assets in the area. This is most relevant to crossing Option 5.  Mulberry Cottage and Mulberry House  Monument to the Ballard Family, in the churchyard and to the south of St Mary’s Church  Monument to David’s and Maynard, in the churchyard to south of St Mary’s Church  The Old Vicarage  Stables and Coach House  Court House Farmhouse There may be a negative impact on these Listed Buildings which are located in close proximity to the option alignment. There is also the potential for a negative impact on the setting of Listed Buildings which would also be a consideration as the project progresses.

Landscape All option alignments are likely to have a substantial Negative landscape and visual impacts effect on local key view points and the Landscape can be potentially (partly) mitigated by Character of the area. The Study Area is located careful design and siting of the within the Bristol, Avon Valleys and Ridges National proposed development. The form and Character Area (NCA) and Severn and Avon Vales layout of the proposed development (NCA). should be designed to relate to the landscape character of the area, taking The Landscape Character Areas (LCA) that are likely into account the landform and to be impacted by the proposed development are: topography of the surrounding area.  North Somerset: C2 Portbury Settled Costal Key viewpoints should be tested as part Edge of the design development process and  North Somerset: J6 Rolling Valley Farmland consultation with local communities will be a key part of the process.  North Somerset: F1 Abbots Leigh Sandstone Uplands  Bristol: Shirehampton

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Environmental Receptors and Potential Impacts Proposed Mitigation Constraints

Geomorphology There is potential for an impact on geomorphology Any negative impacts associated with and and water quality as construction activity could alter geomorphology and water quality Sedimentation the water flow, disturb the river bed, and raise associated with the option alignments sediment into suspension in the area. This would be would be managed by designing out

considered in light of the significant sediment loading some issues where possible, or of the River Avon in the absence of the development. minimising the impact through geomorphological and sediment transport modelling. If any works are required in the river this would require a Marine Management Organisation (MMO) Licence, a Habitats Regulations Assessment (HRA) Likely Significant Effects Screening, and a Water Framework Directive (WFD) Screening assessment.

Air Quality and There may be some negative impacts on air quality The noise and air quality impacts Noise and noise, particularly during the construction phase. associated with the construction phase of the development will be managed The Study Area is not within a UK Air Quality through standard mitigation which Management Area (AQMA). All options are likely to would be discussed by the project lead to elevated noise levels compared to the baseline design team at a later date. during the construction stage of the crossing. However, once operational noise levels are expected to be similar to the baseline, although some localised receptors may experience a slight deterioration in noise levels due to proximity to a new road. During operation, the distribution of traffic flows and predicted reduced congestion (increased traffic speeds) has the potential to lead to a slight improvement in local air quality alongside existing roads.

Planning It is anticipated that all of the option alignments being considered would fall under the Planning Act 2008 and therefore would require a Development Consent Order (DCO). This means that it would be the Secretary of State (via a recommendation from the Planning Inspectorate) rather than the local Council who would be the determining authority for the crossing.

The Planning Act process typically requires a minimum 12 to 18 months to prepare the DCO application, with a further 18 months for examination and determination. This would need to be factored into the overall delivery programme and development budget for the project.

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350000 351000 352000 353000 ^_ Severn Beach Railway Line

AECOM Limited 1 Callaghan Square Cardiff, CF10 5BT +44 (0)29 2067 4600 tel www.aecom.com Project Title:

SECOND AVON CROSSING OPTIONS

Client:

^_ ^_ LEGEND

176000 Station Road Rail Underbridge NCR 26 ^_ Cycle Network PILL NCA - Bristol, Avon Valleys and Ridges ^_ NCA - Severn and Avon Vales

Scale at A3: 1:10,000 ^_ Martcombe Road ^_ ^_ Drawing No: Rev: FIGURE 4 V1 0 125 250 M Source: Esri, DigitalGlobe, GeoEye, Earthstar Geographics, CNES/Airbus DS, USDA, USGS, AEX, Getmapping, Aerogrid, IGN, IGP, Drawn: Chk'd: App'd: Date:

6. ENGINEERING ASSESSMENT - STRUCTURES

Due to the proposed height of the 2AC to clear the existing railways and River Avon it is not considered viable to construct the approach works to the crossing in earthworks. The alignment will need to be carried on structure across these constraints in order to: 1. Minimise the impact on the Ramsar / SAC / SPA / SSSI sites 2. Minimise the loss of flood storage volume and flow conveyance. Four concept designs for the river crossing structure have been proposed noting that other modified concepts could be developed on the basis of these. The use of bascules is proposed to permit vessel passage on the Avon. A bascule bridge is comparable to a drawbridge and is the most common type of movable bridge. It consists of two counterweighted leaves or spans which pivot upward to allow vessels to pass underneath. The counterweights are present to balance each side of the bridge during the upward swing, and contribute to the lifting motion. The proximity of the proposed bridge crossing to the emerging options for a tidal barrier located upstream of Shirehampton (Refer to TFRMS Study for further details and assessment) presents the opportunity to also consider the synergy and any benefits for bringing two major engineering schemes proposals into one. The presented structure concepts for the river crossing vary by the number of spans, methods for providing passage for ships and their potential to be integrated with the tidal barrier. The only aspects of construction that would remain conceptually unaffected by the chosen crossing are the approaches to the bridge from both river banks. For the approach spans on both river banks, recommendation is made for the continuous composite steel (box or girders) and concrete deck structure supported on a simple cross-beam and two Ø1.20 m or Ø1.50m RC columns of the appropriate height. The structural deck depth would be approximately 1.50 m (with the exception of the bascule parts where it is likely to be increased to approximately 3m). 1. Approach spans could range from 25.0 m to 45.0 m to cross the obstacles on the ground (railway lines, roads, pipeline etc.). 2. Any required change in the longitudinal slope and elevation of the approach spans and the bridge crossing itself could easily be accommodated by varying the height of the supporting columns (this applies to any of the considered Options from 1 to 5). One of the benefits of the elevated approach spans is the minimal environmental impact on the surrounding land. (The same type of construction has already been used for the existing M5 bridge over the River Avon.) All four considered structure concepts to cross the river are based on the assumption that the river width is 154 m. Background to Concepts 1 and 2 The first two concepts assume similar continuous steel and concrete composite structure as for the approach spans. Most fundamentally, both concepts could be structurally integrated with a tidal barriers (and lock(s) for the passage of ships, if required) but are also viable as the stand-alone conventional bridge structures. Concept 1 features 5 equal spans (of 30.8 m) across the river with 4 reinforced concrete (RC) piers. It is presented with the optional tidal barrier gates and a ship lock at the central bascule span (of clear width 27.8 m). Concept 2 features 6 spans (of 23 m or 27, as per the sequence shown in Table 3) and presents a possible integrated solution with the tidal barrier and two locks at the central spans with bascules (clear widths 20.0 m). The presented scale is based on the assumption that the river depth is 10.0 m and the clearance from the average water level is 10.5 m leaving approximately 1.20 m minimum clearance for 1:1000y water level. Both concepts are flexible enough to accommodate different elevations across the river. To allow taller ships to pass without the need to interrupt bridge traffic, the clearance can be economically increased by changing the height of the columns that support approach spans.

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Soil conditions and the depth of bedrock are subject to further geotechnical investigation. A high level review of the British Geological Society (BGS) database indicates the following geology:- 1. Superficial deposits of tidal flat deposits of clay, silt, sand and gravel. 2. Bedrock of Westbury Formation and Cotham Member (undifferentiated) mudstone and limestone interbedded. A review of the nearest BGS borehole records sunk prior to the construction of the M5 overbridge indicate superficial deposit depths between 4 m and 9 m below ground level. It is assumed that, due to the depth of the superficial deposits, the piers would be founded on pile caps on deep, reinforced concrete (RC) piles into the bedrock. This type of foundation would be most practical whether the bridge is built separately or as an integrated structure with a tidal barrier. While RC piles could be either drilled (steel encased) or driven into the river from a floating barge, the construction of the piers and the cross heads would require either a temporary bridge structure supported on steel piles or formation of temporary embankments/jetties and coffer-dams. Foundations aside, the proposed composite structure with relatively short spans (up to around 30 m) is very well suited for construction on sites like the Avon crossing. The configuration of the terrain allows for the possibility that the bridge spans are constructed on land and either launched from the river banks (over the abutment and piers) or simply lifted into position using the mobile crane operating from the floating platform, for example. Background to Concept 3 The third concept is also a composite steel and concrete structure, but with three spans approximately 62 m, 30 m and 62 m, respectively, with the bascules at the central span for the passage of tall ships. The construction process for the abutments and two piers in the river could be essentially the same as already outlined for the first two concepts. Only, because of the larger side spans, this three-span composite structure could not be fully integrated with a tidal barrier and should be considered as a stand-alone bridge only. As a stand-alone structure, it may potentially offer advantage over the Concepts 1 and 2 (with 5 and 6 shorter spans) if it can be demonstrated that substantial savings in construction costs could be achieved by reducing the number of piers and, consequently, the scope of foundation works within the river. Background to Concept 4 The fourth explored concept for the river crossing is with a single span bridge structure that could (optionally) be built on supports that could be lifted at both ends to allow passage of taller ships. While it may be possible to introduce tidal barrier with a single span bridge, this would not be an economically feasible engineering solution. Therefore, a single span concept for the river crossing is only recommended if:  The bridge structure and tidal barrier are to be built separately on different locations;  The construction of foundations within the river presents significant technological or financial challenges (pending the more detailed geotechnical investigation). Our preliminary calculations indicate that a 154 m span steel arch structure to carry a single carriage way and two pedestrian and cycling lanes on each side could be built with approximately 1400 tonnes of steel and approximately 200 m3 of concrete for the deck. Off-site construction and the use of a mobile crane operating from the floating platform to install the structure would be recommended in order to minimise the environmental impact of construction on the adjacent land. The desired clearance under the arch could again be achieved by adjusting the height of columns above the abutments.

We summarise the key aspects of each concept in Table 3 below.

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Table 3 – Summary of Engineering Concepts (Structures and Spans) Concept Structure Materials Total Span Segments (m) Bascule present? No. Span (m) 1 continuous steel and 154 5 no. spans x 30.8 m Y concrete composite 2 continuous steel and 154 6 no. spans - 27 + 27 + Y concrete composite 23 + 23 + 27 + 27 3 continuous steel and 154 3 no. spans – 62 + 30 Y concrete composite +62 4 continuous steel and 154 1 no. span N (vessel clearance concrete composite incorporated through bridge deck height)

Four concept design sketches are included in Appendix B.

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7. INTERFACE WITH TIDAL FLOOD RISK MANAGEMENT STRATEGY

The most important conclusion from the structural engineering assessment of the highway crossing is that it would be technically possible to integrate a bridge type structure with a tidal barrier, with or without the use of locks. The cost estimates presented within this feasibility study are based only on the stand-alone bridge structure. An integrated solution would require significant consideration to quantify the potential for reducing the total construction costs of the separate bridge crossing and barrier schemes. For example, this should consider the feasibility of the barrier piers and abutments providing permanent supports for the bridge deck. At this stage, we would recommend a conservative view is taken to potential cost savings through an integrated structure. In the absence of detailed consideration, a target figure of achieving 20% cost savings on the cost of the standalone crossing is suggested as a potential indicator for this study. The basis of this target figure is that if a 50% saving is achieved on the cost of the foundations and piers, this would translate to the order of a 20% saving, say, on the cost of the crossing construction including PC and provisional sums. Section 9 provides the detail for the cost estimates. In comparison to two separate construction schemes, there could be potential additional financial and environmental benefits to BCC from an integrated solution via:

 Simpler procurement process involving one Joint Venture for design and construction.  Shorter construction time and single phase of construction with reduced environmental impact to the site surrounding areas (noting that there could be some environmental disbenefit if the crossing solution is a multiple narrow span concept (1 and 2) versus large span concepts (3 and 4))  Lower long-term maintenance costs for the integrated bridge-barrier structure.

As described in Section 3 above, the option alignment that is closest to the potential wide barrier location in the R Avon TFRMS is Option 2. A barrier has not been considered downstream of the M5 bridge, which reduces the potential for considering synergy with a highway crossing at this location. However, Option 4, along with Options 1 and 5 are not perpendicular crossings and are therefore less suited to integration because of flow impedance, particularly Option 5. This leaves Option 2 as the only location with the potential for some synergy with a tidal barrier, based on the locations studied to date, i.e. additional further studies would need to be undertaken to consider other potential barrier / crossing locations.

As stated in Section 3, none of the crossing options have synergy with the narrow barrier location considered by the TFRMS.

If Option 2 was progressed, of the four presented structure concepts to cross the river, the best suited for integration with a tidal barrier (or barrage type structure with locks) would be Concept 1 and Concept 2. These concepts are provided in Appendix B.

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8. TRANSPORT CONNECTIVITY

The transport connectivity for all vehicles, pedestrians and cyclists has been assessed based on the following criteria:

1. Motorised vehicles including local and potential diverted traffic off the M5 Motorway – Total diverted distance from Junction 18 to 19 of the M5 2. Public Transport – distance from existing railway stations, bus routes and Park and Ride site (assumed maximum walking distance 400m for able bodies persons but considerably less for disabled persons) 3. Pedestrians and Cyclists – distance from existing footways, footpaths & cycleways. Refer to Table 5 in Section 10 for table of transport connectivity analysis.

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9. COST ESTIMATES

Bases of Estimates An Order of Cost Estimate has been prepared for to provide indicative feasibility costs for the proposed 2AC. The outline design proposes 5 separate option alignments. Due to the preliminary nature of the proposal, the estimate has been prepared in advance of detailed information being available. This estimate should therefore be subject to continuous review, as the design and available information develops, in accordance with the Client's brief. The estimates have been priced at 3rd Quarter 2016 and include Preliminaries, Contingency/Design Review/Risk and Professional Fees. Allowance for inflation beyond this date has been included - assuming construction commencing Q1 2018, completing in Q4 2020. The costs contained in this estimate are based upon historic, empirical data collated from previous projects and benchmarked against other projects of a similar nature, albeit with a number of adjustments and assumptions identified within this report.

Assumptions and Key Points The following assumptions have been made in preparing this cost model. For clarity, several key points are also noted: 1. The high level AECOM cost estimate was produced with extremely limited design / scoping information, and should be reviewed against more definitive information once it becomes available. 2. Costs represent a forecasted price, at 3rd Quarter 2016, assuming a fixed price basis. 3. We have assumed competitive tenders will be sought. 4. The preliminaries / construction supervision allowance of 30% is based upon similar projects recently completed and includes due allowances for the nature of the site and maintaining/altering safe and adequate access/egress to the works. 5. Pricing takes account of the following risk conditions: 6. Working over tidal waterways 7. Working at height 8. Working over live rail networks 9. Notional Provisional Sum allowances have been included for all options. 10. We have assumed 15.00m wide deck/road (including margins), with approach roads either end. 11. Provisional allowances are included for road junctions connecting new road layouts to existing, including traffic signals. 12. Site clearance/earthworks/drainage/service ducts are included within rates for roads/structures. 13. The costing of jetties / retaining structures should be revisited when more detailed design information is available. 14. Temporary works have been included within preliminaries / construction supervision allowances, which represent 30% of the construction and maintenance costs for each option. 15. Approach roads are assumed at grade and not elevated. 16. Items have been excluded from the estimate where design scope is not currently defined enough to include even high level allowances. 17. Optimism bias has been applied to the total costs at a rate of 44%. This has been added at the request of BCC, and is in line with Department for Transport guidance on scheme costs (TAG Unit A1.2 guidance notes), specifically the Roads Category (Stage 1) in Table 8 - Recommended optimism bias uplifts for different projects at different stages of the life of a transport project. Exclusions

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The following items are excluded from this cost model: 1. VAT 2. Inflation beyond completion 3. Land acquisition costs 4. Property compulsory purchase costs 5. Legal fees 6. Client internal administration costs 7. Offsite highways works 8. Enhanced off site drainage to improve capacities 9. Consents 10. Water pumping stations 11. Client insurances and/or other Client direct costs 12. Additional works resulting from surveys, service investigations and geotechnical works 13. Offsite infrastructure works and upgrades 14. Alterations to existing premises 15. Barrier related works/bridges etc.

Note on Land Costs and Operation & Maintenance Costs Land values are a very difficult thing to quantify, particularly since the sort of land that could be needed for 2AC is not standard city centre brownfield land, i.e. the sort of which a commercial developer would purchase, and the costs are better understood. Our experience has demonstrated that a 'typical range' because of large variance between different projects in different locations. We would recommend that a local land agent, perhaps via existing BCC frameworks, could be approached to provide an estimate. In terms of bascule bridge operating costs, the recently submitted Outline Business Case for a third crossing at Lowestoft, Lake Lothing Third Crossing, Lowestoft, provides an estimate for operation and maintenance costs. The OBC suggests annual highway maintenance costs of £10k per year and operation and maintenance of the bridge to amount to £132k per year. In cash terms (2015 Q4 including risk adjustment) this is reported to be £11.7m in total for a 60 year scheme. Also in Lowestoft, a FoI request for an existing bascule bridge identified that over 7 financial years (2007- 2015), around £5.5m was spent on bridge operation and maintenance. The wider river at Avonmouth and different types of vessel traffic would need to be considered when making comparisons for a potential 2AC. The cost estimates presented in Appendix C, include line items for maintenance infrastructure (£1M) and Operation and Maintenance Manual (£100k). We provide these figures after completing our own estimate / review of potential operation and maintenance costs and estimate these would amount to the order of £1m per year, and would recommend this is used as an initial indicator at this stage of the project.

Summary Table 4 provides a summary of the estimates for all alignment options. A more detailed breakdown is provided in Appendix C. The total cost estimate for each option, rounded up to the nearest million is:  Option 1 (complete scheme) £242m  Option 2 (combination of Option 1 and Option 2 alignments) - £241m  Option 3 (combination of Option 3 and Option 2 alignments) £262m  Option 4 (combination of Option 3 and Option 4 alignments) £243m  Option 5 (combination of Option 1 and Option 5 alignments) £281m

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Table 4 – Cost Estimate Summary

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10. ASSESSMENT OF OPTIONS

Assessment Criteria The following set of scheme objectives has been selected as criteria against which to assess the options. These are based on the Client Brief and reflective of the proposal criteria. 1. Existing constraints as described in Section 2. 2. Effect on land and property. 3. Effect on environmental aspects including Archaeology and Built Heritage, Landscape, Geomorphology and Sedimentation and Air Quality and Noise, as described in Section 5. 4. Potential synergy (geographical location) with a tidal barrier option, as described in Section 7. 5. Transport connectivity, as described in Section 8. 6. Cost estimates as described in Section 9.

The crossing options can be interlinked and have been assessed insofar as the permitted combinations would be: 1. Option 1 – Complete Scheme. 2. Option 2 (combination of Option 1 & 2) - Option 1 to Portbury and Portishead rail lines followed by Option 2 to A4 Portway. 3. Option 3 (combination of Option 3 & 2) – Option 3 and the north eastern section of Option 2 over the Avon to the A4 Portway. 4. Option 4 (combination of Option 3 & 4) - Option 3 merging with the southern starting point of Option 4. 5. Option 5 (combination of Option 1 & 5) - Option 1 to Severn Beach railway crossing followed by Option 5 to A4 Portway.

Scoring Criteria 1. Existing constraints (non-environmental)  Based on cumulative scores in Table 5, which indicates the presence or not of a constraint. A ranking from 1 to 5, where 1 has the most constraints (lowest net score) and 5 has the least number of constraints (via highest net score in Table 5) is then used to compare the relative scores for non-environmental constraints in Table 7. 2. Effect on land and property (as presented in Table 5) – it is anticipated that land outside of BCC ownership would be required. Therefore:  Only land affected scores 3.  Less than 5 properties affected scores 2.  More than 5 properties affected scores 1. 3. The likelihood of environmental effects (Ecology, Archaeology and Built Heritage, Landscape, Geomorphology and Sedimentation, and Air Quality and Noise) without mitigation is captured in Table 5. The significance of the scores for each theme is included in Table 7, as follows: o No impact scores 5. o Some impact scores 3. o Most impact scores 1. 4. Transport connectivity, shown in Table 6  Ranking from 1 (least connected) to 5 (most connected). 5. Synergy (geographical location and orientation) with tidal barrier option, shown in Table 7

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 No synergy scores 1.  Potential synergy scores 3. 6. Cost estimate Rank 1 to 5, where 1 is highest cost estimate and 5 is lowest cost estimate. Note: The basis of the colour coding in the scoring tables below is green is positive, red is negative and yellow is neither wholly positive nor wholly negative. The indicative net score shown in tables is a count of the positive scores minus negative / possible scores. For example, if an option has 8 greens, 12 reds and 4 yellows, the net score would be -8. Crossing Option No. 1 2 3 4 5 Constraint Affected Y/N/?Possibly Highways A4 Portway Station Road Shirehampton Martcombe Road Marsh Lane Tie in to Marsh Lane downstream of M5 Tie in to Gordano Way / Royal Portbury Dock Rd M5 Overbridge Existing Park & Ride site Land Existing housing at Lodway and Pill Existing Land at Shirehampton Existing Gordano Motorway Services Existing car storage areas Existing industrial area in Avonmouth Rail Severn Beach Railway Line Royal Portbury Dock Railway Line Portishead Railway Line Station Road Rail Underbridge Utilities Oil pipeline Overhead cables Environment Ecology Archaeology and Built Heritage Landscape Geomorphology and Sedimentation Air Quality and Noise Totals 12 13 9 8 14 Totals 4 4 4 5 3 Totals 8 7 11 11 7 Indicative Net Score (N-Y-Possibly) -8 -10 -2 -2 -10

Table 5 – Existing non-environmental and environmental constraints Note on potential showstoppers with respect to constraints:  Options 3 and 4 may be affected by the Hinkley Connection project. Available maps for the Hinkley connection consent application show that Option 4 and Option 3 may be constrained on the landing side to the west of the Avonmouth M5 bridge (south bank). This could be a potential showstopper for these options.  Option 4 has an added impact on a SBL level crossing a significant increase in the amount of traffic using the level crossing may not acceptable to Network Rail which may force the rejection of this option. We have reviewed the alignment, and given the congestion locally of M5 bridge piers and the constrained local road network a grade

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separated option could be a "showstopper". The requirement for additional carriageway, extra structural foundations and earthworks, and potential demolitions to provide accommodation space, combined with the need to accommodate highway and railway safety considerations are predicted to be extremely difficult to resolve.  Option 5 requires revised headroom at the Severn Beach Line Bridge which could prove prohibitively expensive and thereby is a potential showstopper.

Option no. 1 2 3 4 5 Motorised vehicles travel distance (km) 6.6 6.9 6.7 6.6 7.2 Access to railway station Y/N/?Potentially Access to existing bus routes Y/N/?Potentially Access to existing Park and Ride site Y/N/?Potentially Access to existing footways Y/N/?Potentially Access to existing footpaths Y/N/?Potentially Access to existing cycleways Y/N/?Potentially Totals 1 2 1 - 1 Totals 1 1 - 2 2 Totals 4 3 5 4 3 Indicative Net Score (Y-N-Potentially) 2 0 4 2 0 Table 6– Transport Connectivity

Option no. / Criteria 1 2 3 4 5 (complete (combination of (combination of (combination of (combination of scheme) Option 1 & 2) Option 3 & 2) Option 3 & 4) Option 1 & 5)

Existing non- 3 1 5 5 2 environmental Constraints

Land and Property 2 3 2 3 1

Environmental Constraints

Ecology 1 1 1 1 1

Archaeology and Built 3 3 3 3 1 Heritage

Landscape 3 3 3 3 3

Geomorphology and 3 3 3 3 3 Sedimentation

Air quality and Noise 3 3 3 3 3

Transport Connectivity 4 3 5 4 3

Synergy with TFRMS 1 3 3 1 1

Cost estimate 5 5 2 3 1

Total 28 28 30 29 18

Table 6 – Overall Assessment

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11. CONCLUSIONS AND RECOMMENDATIONS

Conclusions The study has identified 5 potential alignments for 2AC. The range of costs for the alignments varies between £241 and £281 million, including optimism bias at 44%. A multi-criteria analysis has been undertaken on the options, which has looked at infrastructure and environmental constraints, land and property, transport connectivity and potential synergy with a tidal barrier. These criteria have been combined with the cost estimates to rank the overall score of the different options and options for further studies. From the assessment undertaken in Section 10 it can be concluded that:- 1. Option 5 has the lowest overall score. The option scores poorly, and worse than other options, on existing non-environmental constraints, land and property, archaeology and built heritage. It is not as well connected. This is the most expensive option due to high cost of the long structure and tying in works at Shirehampton. It has weak synergy with a tidal barrier because it doesn’t coincide with the wide barrier location developed in the TFRMS, and it also has a non-perpendicular alignment. This option also has a potential showstopper issue, in that it would require revised headroom at the Severn Beach Line Bridge which could prove prohibitively expensive. 2. Option 4 has the second highest overall score, but only marginally over Options 1-3. It scores relatively well in terms of existing non-environmental constraints, land and property and transport connectivity. It is only marginally more expensive than the cheapest options (1 and 2). It does not have synergy with the tidal barrier options considered by the TFRMS (location and orientation). There are potentially two showstopper issues, however, with this option. These relate to the Hinkley Connection project being coincident with the landing side on the south bank. The second issue is a conflict with the Severn Beach Line crossing, which could be technically and financially challenging, and difficult to satisfy regulatory interests (Network Rail and Bristol City Council (Highway Authority). 3. Options 1-2 have the same overall score, and only marginally lower than Options 3 and 4. The criteria scores vary across the options. On existing non-environmental constraints, Option 1 fares better than Option 2. Option 2 is marginally better in terms of land and property. Option 1 scores higher on transport connectivity than Option 2. Options 2 is one of two options (the other is Option 3) where there is synergy with the wide barrier option developed in the TFRMS, in terms of location proximity and an almost perpendicular alignment. Options 1 and 2, are the cheapest options. 4. Option 3 has the highest score, marginally. It has the best score on non-environmental constraints. Option 3 scores the highest on transport connectivity. This option has synergy with the wide barrier option, like Option 2. However, Option 3 is comparatively more expensive than Options 1 and 2 (and Option 4) and is exceeded in cost by Option 5 only. There is also a potential showstopper in terms of the Hinkley Connection project because it is coincident with the landing side on the south bank. 5. All options have similar, poor scores on a number of key environmental themes, namely ecology, landscape, geomorphology and sedimentation, and air quality and noise. It is difficult to separate out the environmental merits of the schemes at this early stage of the project.

Recommendations 1. Option 5 should not be considered further; its merits are poor compared with other options, it is most expensive, does not have the best transport connectivity and has no synergy with tidal barrier options considered by the TFRMS. It also has a potential showstopper issue (Severn Beach Line Bridge headroom). 2. Despite its marginal highest score, Option 4, this option has two potential showstopper issues (Hinkley Connection project constraint and Severn Beach Line level crossing). Before going further with this option, additional investigation is recommended to resolve these showstoppers and the crossing issue, which may take significant consultation between the regulatory authorities to provide a mutually acceptable solution.

2AC High Level Feasibility Report 22

3. Options 1, 2 and 3 are recommended to be taken forward for more detailed study. The influence of the Hinkley Connection project on Option 3 would be necessary to resolve this potential showstopper. The alignment of Option 1 should be considered to see if a perpendicular river crossing is possible; this would allow for potential synergy with a barrier structure. However, to do this, further study would be necessary to assess the merits of a barrier in this location. It is recommended that the non-environmental constraints are investigated further for Option 2 to confirm their significance.

Compliance with Brief The brief asked a number of questions to be answered by the study. These questions and the answers are provided below for ease of reference: 1. Is the SAC technically feasible; is there an alignment that would work? We have developed a number of technically feasible alignments, and ranked them to identify the preferred options. Recommendations are made to investigate these options further (Options 1-3). 2. What engineering challenges are posed by the SAC? What might the costs be as a standalone build as opposed to a joint build alongside a tidal barrier? The engineering challenges / constraints are listed, presented and have been assessed. The costs of the highway crossing options are presented in detail, along with consideration of potential savings from a highway crossing combined with a tidal barrier. 3. What environmental challenges are posed by the alignment and engineering solutions proposed? The environmental challenges are identified, discussed and potential mitigation is described. 4. What is the likely BCR of a SAC as a standalone build and does this change if the cost is shared between the SAC and a tidal barrier? What measure of benefit would be applicable? A combined highway crossing and barrier option would not change the measure of benefit concerning journey time saving vs the "do nothing" scenario. In order to establish the BCR of 2AC, it would be necessary to undertake detailed traffic modelling, to test the options vs the "do nothing"; this is work is being completed by other consultants for BCC, and the cost estimates in this report are key to that task.

2AC High Level Feasibility Report 23

A VERTICAL ALIGNMENTS

2AC High Level Feasibility Report 24

PROJECT

ISO A1 594mm x 841mm ISO A1 594mm TIE INTO MARTCOMBE ROAD Alignment - OPTION 1 Lone1 PROFILE SECOND AVON 38 38 38 36 36 36

34 34 TE 34 CROSSING 32 32 32 30 30 30 28 28 28 26 26 26 Approved: 24 24 24 TIE INTO PORTWAY 22 22 22 20 20 20

SWE 18 18 18 16 16 16 CLIENT 14 14 14 12 12 12

10 10 Checked: 10 DECK BRISTOL CITY 8 8 FREEBOARD 8 6 6 MARSH LANE SEVERN BEACH 6 4 PORTISHEAD RAILWAY LINE 4 DC 4 COUNCIL 2 2 RAILWAY LINE 2 0 0 0 Bristol City Council -2 AVON -2 -2 Bristol -4 -4 -4 Designer: City Hall, PO Box 3176

0+000 0+020 0+040 0+060 0+080 0+100 0+120 0+140 0+160 0+180 0+200 0+220 0+240 0+260 0+280 0+300 0+320 0+340 0+360 0+380 0+400 0+420 0+440 0+460 0+480 0+500 0+520 0+540 0+560 0+580 0+600 0+620 0+640 0+660 0+680 0+700 0+720 0+740 0+760 0+780 0+800 0+820 0+840 0+860 0+880 0+900 0+920 0+940 0+960 0+980 1+000 1+020 1+040 1+060 1+080 1+100 1+120 1+140 1+160 1+180 1+200 1+220 1+240 1+260 1+280 1+300 1+320 1+340 1+360 1+380 1+400 1+420 1+440 1+460 1+480 1+500 1+520 1+540 1+560 1+580 1+600 1+620 1+640 1+660 1+680 1+700 1+720 1+740 1+760 1+780 1+800 1+820 1+840 1+860 1+880 1+900 1+920 1+940 1+960 1+980 2+000 2+020 2+040 2+060 2+080 2+100 2+120 2+140 2+160 2+180 2+200 2+220 2+240 2+260 0+000 0+100 0+200 0+300 0+400 0+500 0+600 0+700 0+800 0+900 1+000 1+100 1+200 1+300 1+400 1+500 1+600 1+700 1+800 1+900 2+000 2+100 2+200 BS3 9FS

SAC INITIAL LONG SECTION OPTION 1 ONLY CONSULTANT 1:2500 H, 1:250 V 50KPH Project Management Initials: Project Management AECOM 1 CALLAGHAN SQUARE CARDIFF CF10 5TB TEL: (029) 20674600 FAX: (029) 20674699

TIE INTO MARTCOMBE ROAD NOTES

option 1- (1) PROFILE

36 36 36 34 34 34 32 32 32 30 30 30 28 28 28 26 26 26 TIE INTO PORTWAY 24 24 24 22 22 22 20 20 20 18 18 18 16 16 16 14 14 14 12 12 12 DECK 10 10 10

8 FREEBOARD 8 8 6 6 6 MARSH LANE SEVERN BEACH 4 4 4 PORTISHEAD RAILWAY LINE 2 2 2 0 RAILWAY LINE 0 0 AVON -2 -2 -2 -4 -4 -4

0+000 0+020 0+040 0+060 0+080 0+100 0+120 0+140 0+160 0+180 0+200 0+220 0+240 0+260 0+280 0+300 0+320 0+340 0+360 0+380 0+400 0+420 0+440 0+460 0+480 0+500 0+520 0+540 0+560 0+580 0+600 0+620 0+640 0+660 0+680 0+700 0+720 0+740 0+760 0+780 0+800 0+820 0+840 0+860 0+880 0+900 0+920 0+940 0+960 0+980 1+000 1+020 1+040 1+060 1+080 1+100 1+120 1+140 1+160 1+180 1+200 1+220 1+240 1+260 1+280 1+300 1+320 1+340 1+360 1+380 1+400 1+420 1+440 1+460 1+480 1+500 1+520 1+540 1+560 1+580 1+600 1+620 1+640 1+660 1+680 1+700 1+720 1+740 1+760 1+780 1+800 1+820 1+840 1+860 1+880 1+900 1+920 1+940 1+960 1+980 2+000 2+020 2+040 2+060 2+080 2+100 2+120 2+140 0+000 0+100 0+200 0+300 0+400 0+500 0+600 0+700 0+800 0+900 1+000 1+100 1+200 1+300 1+400 1+500 1+600 1+700 1+800 1+900 2+000 2+100

SAC INITIAL LONG SECTION OPTION 1 AND 2 1:2500 H, 1:250 V 50KPH

ISSUE/REVISION

TIE INTO PORTWAY

TIE INTO GORDANO WAY

Option 3 PROFILE

18 18 18 16 16 16 14 14 14 A 2016-11-01 FOR ISSUE 12 12 12 DECK 10 10 10 I/R DATE DESCRIPTION

8 FREEBOARD 8 8 6 6 6 4 MARSH SEVERN BEACH 4 KEY PLAN 4 PORTISHEAD 2 LANE RAILWAY LINE 2 2 RAILWAY LINE 0 0 0 -2 AVON -2 -2 -4 -4 -4 -6 -6 -6

0+000 0+020 0+040 0+060 0+080 0+100 0+120 0+140 0+160 0+180 0+200 0+220 0+240 0+260 0+280 0+300 0+320 0+340 0+360 0+380 0+400 0+420 0+440 0+460 0+480 0+500 0+520 0+540 0+560 0+580 0+600 0+620 0+640 0+660 0+680 0+700 0+720 0+740 0+760 0+780 0+800 0+820 0+840 0+860 0+880 0+900 0+920 0+940 0+960 0+980 1+000 1+020 1+040 1+060 1+080 1+100 1+120 1+140 1+160 1+180 1+200 1+220 1+240 1+260 1+280 1+300 1+320 1+340 1+360 1+380 1+400 1+420 1+440 1+460 1+480 1+500 1+520 1+540 1+560 1+580 1+600 1+620 1+640 1+660 1+680 1+700 1+720 1+740 1+760 1+780 1+800 1+820 1+840 1+860 1+880 1+900 1+920 1+940 1+960 1+980 2+000 2+020 2+040 2016-11-02 0+000 0+100 0+200 0+300 0+400 0+500 0+600 0+700 0+800 0+900 1+000 1+100 1+200 1+300 1+400 1+500 1+600 1+700 1+800 1+900 2+000

AVON M5 O/B

Last Plotted: Last Plotted: PROJECT NUMBER 60478613 SHEET TITLE CASSIDYD SAC INITIAL LONG SECTION OPTION 2 AND 3 SECOND AVON CROSSING 1:2500 H, 1:250 V 50KPH VERTICAL ALIGNMENTS OPTIONS 1 TO 3 F:\PROJECTS\HIGHWAYS - SECOND AVON CROSSING FEASIBILITY STUDY\03 EXECUTION\03 DOCUMENTS\01 DISCIPLINES - HIGHWAYS\02 WORKING\SHEETS\AVON M5 OB LONG SECTIONS OB LONG M5 WORKING\SHEETS\AVON - HIGHWAYS\02 DISCIPLINES DOCUMENTS\01 EXECUTION\03 STUDY\03 FEASIBILITY CROSSING AVON - SECOND F:\PROJECTS\HIGHWAYS Last saved by: Last saved SHEET NUMBER FIGURE 3 Filename: Filename: 1-3.DWG Printed on ___% Post-Consumer Recycled Content Paper PROJECT ISO A1 594mm x 841mm ISO A1 594mm SECOND AVON

TE CROSSING Approved: SWE CLIENT TIE INTO GORDANO WAY

Checked: LEVEL BRISTOL CITY CROSSING

DC COUNCIL Bristol City Council Bristol

Designer: SEVERN BEACH City Hall, PO Box 3176 RAILWAY LINE MARSH PORTISHEAD BS3 9FS LANE RAILWAY LINE TIE INTO VICTORIA ROAD AVON

CONSULTANT Project Management Initials: Project Management AECOM 1 CALLAGHAN SQUARE CARDIFF CF10 5TB TEL: (029) 20674600 FAX: (029) 20674699 SAC INITIAL LONG SECTION OPTION 3 AND 4 1:2500 H, 1:250 V 50KPH

TIE INTO MARTCOMBE ROAD

ISSUE/REVISION

TIE INTO STATION ROAD

A 2016-11-01 FOR ISSUE I/R DATE DESCRIPTION MARSH LANE PORTISHEAD KEY PLAN RAILWAY LINE

AVON 2016-11-02

Last Plotted: Last Plotted: PROJECT NUMBER 60478613

CASSIDYD SHEET TITLE SAC INITIAL LONG SECTION OPTION 1 AND 5 SECOND AVON CROSSING 1:2500 H, 1:250 V 50KPH VERTICAL ALIGNMENTS OPTIONS 4 AND 5 F:\PROJECTS\HIGHWAYS - SECOND AVON CROSSING FEASIBILITY STUDY\03 EXECUTION\03 DOCUMENTS\01 DISCIPLINES - HIGHWAYS\02 WORKING\SHEETS\AVON M5 OB LONG SECTIONS OB LONG M5 WORKING\SHEETS\AVON - HIGHWAYS\02 DISCIPLINES DOCUMENTS\01 EXECUTION\03 STUDY\03 FEASIBILITY CROSSING AVON - SECOND F:\PROJECTS\HIGHWAYS Last saved by: Last saved SHEET NUMBER FIGURE 3 (CONTINUED) 4&5.DWG Filename: Filename: Printed on ___% Post-Consumer Recycled Content Paper

B CONCEPT DESIGN SKETCHES

2AC High Level Feasibility Report 25

Clear width for the passage of ships: 27.8 m

10 m to +20 m

water depth 11 m

30.8 m 30.8 m 30.8 m 30.8 m 30.8 m

154.0 m (total bridge length)

CONCEPT 1:

5 x 30.8 SPANS (with or without the tidal barrier and locks).

All spans composite steel + concrete deck (width 15.0 m), total depth of the deck structure in the region 1.50 m (subject to detailed design); possibly 3.0 m to 3.0 m near the central piers.

Note: A rectangular shape for the channel was deducted from the height profile for one of the crossing options and is used on all the concept details. It has no impact on the presented concepts which should be considered as illustrative only at this stage.

CONCEPT 2:

6 x 25.1 SPANS (with or without the tidal barrier and two optional locks).

All spans composite steel + concrete deck (width 15.0 m), total depth of the deck structure in the region 1.50 m (subject to detailed design); possibly 3.0 m to 3.0 m for the bascules above the two central spans and lock gates.

Clear width for the passage of ships: 27.8 m 10 m to +20 m

water depth 11 m

61.6 m 30.8 m 61.6 m

154.0 m (total bridge length)

CONCEPT 3:

3 SPANS (61.60 m + 30.80 m + 61.60 m; variations possible to suit particular width for the passage of ships.

All spans composite steel + concrete deck (width 15.0 m), total depth of the deck structure in the region 2.0 m (subject to detailed design), possibly 3.0 to 4.0 near the central piers. 18.0 m

10 m to +20 m

water depth 11 m

154.0 m (total bridge length)

CONCEPT 4:

154 m span ARCH, central height 18.0 m.

Bottom/top chords steel boxes (approx. 1.0 m width/ 2.0 m height), possibly RC deck 20 cm thickness, lightweight external deck structure for pedestrian and cycling lanes. In the absence of the more detailed design, for a single carriageway arch bridge and 2 x (1.50 m + 1.50 m pedestrian/cycling lanes on each side) the estimated steel weight 1400 tonnes + RC deck 250 m3 concrete + est. 500 tonnes for the surfacing. Construction by lifting from the barge is possible, either in a single lift (depending on the max available crane capacity) or in three parts (deck + two arches). CONCEPT 1: isometric view

Concept 2: isometric view of the low-level crossing with (optional) closed tidal barrier and one lock gate open