A27 Chichester Bypass
Technical Appraisal Report
343538-90-060-RE-002-P02 September 2015 Project Support Framework (Consultancy) 2011 – 2016 A27 Chichester Bypass Technical Appraisal Report
A27 Chichester Bypass
Technical Appraisal Report
343538-90-060-RE-002-P02
Revision Record Revision Date Originator Checker Approver Description No P01 29 May 2015 First Issue P02 2 Sept 2015 Revised following SGAR1 comments
This document has been prepared on behalf of Highways England by Mott MacDonald Grontmij JV for Highways England's Project Support Framework (PSF) (Consultancy) 2011-2016. It is issued for the party which commissioned it and for specific purposes connected with the above-captioned project only. It should not be relied upon by any other party or used for any other purpose.
Mott MacDonald Grontmij JV accepts no responsibility for the consequences of this document being relied upon by any other party, or being used for any other purpose, or containing any error or omission which is due to an error or omission in data supplied to us by other parties.
This document contains confidential information and proprietary intellectual property. It should not be shown to other parties without consent from Mott MacDonald Grontmij JV and from the party which commissioned it.
Prepared for: Prepared by: Highways England Mott MacDonald Grontmij JV 1 Walnut Tree Close Stoneham Place Guildford Stoneham Lane Surrey Southampton GU1 4LZ SO50 9NW Project Support Framework (Consultancy) 2011 – 2016 A27 Chichester Bypass Technical Appraisal Report
Contents Page
Executive Summary ...... 1
1 Introduction ...... 5
2 Planning Brief ...... 6 2.1 Project Objectives ...... 6 2.2 Understanding the Current Situation ...... 7 2.2.1 Operational and Capacity Situation ...... 7 2.2.2 Safety Situation ...... 10 2.2.3 Social and Environmental Situation ...... 11 2.3 Understanding the Future Situation ...... 11 2.4 Need for Intervention ...... 12
3 Existing Conditions ...... 14 3.1 Description of the Locality ...... 14 3.1.1 The City of Chichester and District ...... 14 3.1.2 A27 Chichester Bypass ...... 15 3.2 Traffic ...... 16 3.3 Accidents and Journey Time Reliability ...... 17 3.3.1 Accident Analysis Methodology ...... 17 3.3.2 Accident Analysis – A27 Route Overview ...... 17 3.3.3 Journey Time Reliability ...... 19 3.4 Topography, Land Use, Property and Industry ...... 19 3.4.1 Topography ...... 19 3.4.2 Land Use, Property and Industry ...... 19 3.5 Climate ...... 20 3.6 Drainage ...... 22 3.6.1 Existing Situation ...... 22 3.6.2 Proposed Drainage ...... 23 3.7 Geology ...... 24 3.7.1 Geology along the existing Chichester Bypass ...... 25 3.7.2 Surrounding Geology ...... 25 3.8 Mining ...... 26
- i - Project Support Framework (Consultancy) 2011 – 2016 A27 Chichester Bypass Technical Appraisal Report
3.9 Accessibility ...... 26 3.10 Integration ...... 26 3.11 Environment...... 27 3.12 Public Utilities ...... 27 3.12.1 General ...... 27 3.12.2 Fishbourne Junction ...... 28 3.12.3 Fishbourne to Stockbridge Link ...... 28 3.12.4 Stockbridge Link Road (SLR) ...... 29 3.12.5 Stockbridge Junction ...... 29 3.12.6 Whyke Junction ...... 29 3.12.7 Bognor Road Junction ...... 30 3.12.8 Oving Junction ...... 30 3.12.9 Portfield Junction ...... 30 3.12.10 Summary of C3 Estimates ...... 30
4 Planning Factors ...... 32 4.1 Local Planning Policy ...... 32 4.2 West Sussex Transport Plan ...... 32 4.3 Chichester District Council Local Plan ...... 33 4.4 Options Constraints ...... 34
5 Description of Route Options ...... 36 5.1 Introduction ...... 36 5.2 Online Option Development ...... 36 5.2.1 Online Options General Notes ...... 36 5.2.2 Fishbourne Junction ...... 37 5.2.3 Stockbridge Junction ...... 40 5.2.4 Whyke Junction ...... 43 5.2.5 Bognor Road Junction ...... 46 5.2.6 Oving Junction ...... 48 5.2.7 Portfield Junction ...... 49 5.2.8 Stockbridge Link Road ...... 52 5.2.9 Online Option Descriptions ...... 52 5.3 Offline Option Development ...... 54 5.3.1 Design Strategy ...... 54
- ii - Project Support Framework (Consultancy) 2011 – 2016 A27 Chichester Bypass Technical Appraisal Report
5.3.2 Offline Route Selection and Refinement ...... 54 5.3.3 Offline Route Descriptions ...... 56 5.3.4 Hybrid Route Descriptions ...... 66 5.4 Other Options ...... 71 5.4.1 Tunnel ...... 71 5.4.2 Collector Distributor Lane ...... 71 5.4.3 Viaduct over the existing Chichester Bypass ...... 71 5.4.4 Public Transport Option ...... 71 5.5 Environmental Status ...... 72 5.5.1 Introduction ...... 72 5.5.2 Proposed Route Options ...... 72 5.5.3 Environmental Status ...... 73
6 Traffic Analysis ...... 78 6.1 Introduction ...... 78 6.2 Traffic Data ...... 78 6.3 Traffic Modelling Methodology ...... 79 6.3.1 Base year model ...... 79 6.3.2 Traffic forecasting ...... 80
7 Economic Assessment ...... 81 7.1.1 TUBA Assumptions ...... 82 7.1.2 Construction Delay ...... 82 7.1.3 Transport Economic Efficiency - Maintenance Delay ...... 82 7.1.4 Accidents Assumptions ...... 83
8 Safety assessment ...... 84 8.1 Impact on road user – Strategic Safety Action Plan...... 84 8.2 Safety of Road Workers ...... 84 8.3 Road Safety Review of Stage 1 PCF Options ...... 85 8.3.1 Offline Options ...... 85 8.3.2 Online Options (Options 1, 2, 11, 13, 15, 19, W & X) ...... 85 8.3.3 Online Option 1 ...... 85 8.3.4 Online Option 2 ...... 87 8.3.5 Online Option 11 ...... 88
- iii - Project Support Framework (Consultancy) 2011 – 2016 A27 Chichester Bypass Technical Appraisal Report
8.3.6 Online Option 13 ...... 90 8.3.7 Online Option 15 ...... 92 8.3.8 Online Option 19 ...... 93 8.3.9 Online Option W ...... 95 8.3.10 Online Option X ...... 96
9 Maintenance assessment ...... 99 9.1.1 Online and Offline - Flooding ...... 99 9.1.2 Offline - Maintenance Access ...... 99 9.1.3 Offline - Vegetation Growth and Trees ...... 100 9.1.4 Online and Offline - Vehicle Restraint Systems ...... 100 9.1.5 Offline - Signs ...... 100 9.1.6 Online - Structures ...... 100 9.1.7 Offline - Future Design ...... 100
10 Environmental assessment ...... 102 10.1 Introduction ...... 102 10.2 Consultation with Statutory Environmental Bodies ...... 102 10.3 Noise ...... 102 10.3.1 Online Options ...... 102 10.3.2 Offline Options ...... 103 10.3.3 Further Assessment ...... 103 10.4 Local Air Quality ...... 103 10.4.1 Online Options ...... 103 10.4.2 Offline Options ...... 103 10.4.3 Further Assessment ...... 103 10.5 Greenhouse Gases ...... 104 10.5.1 Online and Offline Options ...... 104 10.5.2 Further Assessment ...... 104 10.6 Landscape and Townscape ...... 104 10.6.1 Online Options ...... 104 10.6.2 Offline Options ...... 104 10.6.3 Further Assessment ...... 105 10.7 Heritage and Historic Resources ...... 105 10.7.1 Online Options ...... 105
- iv - Project Support Framework (Consultancy) 2011 – 2016 A27 Chichester Bypass Technical Appraisal Report
10.7.2 Offline Options ...... 105 10.7.3 Further Assessment ...... 106 10.8 Biodiversity ...... 106 10.8.1 Online Options ...... 106 10.8.2 Offline Options ...... 106 10.8.3 Further Assessment ...... 107 10.9 Water Environment ...... 107 10.9.1 Online Options ...... 107 10.9.2 Offline Options ...... 107 10.9.3 Further Assessment ...... 108
11 Assessment Summary...... 109 11.1 Appraisal Summary Tables (AST) ...... 109 11.2 Summary of consultation with public bodies ...... 109 11.2.1 Stakeholders Workshops ...... 110 11.2.2 A27 Focus Group ...... 110 11.2.3 Engagement of Statutory Environmental Bodies ...... 111 11.3 Comparison of Options ...... 112
12 Programme ...... 113
13 Conclusion and Recommendations ...... 114 13.1 Summary of option sifting results ...... 114 13.2 Options to be taken to Stage 2 ...... 115
14 Detailed cost estimate ...... 116 14.1 Assumptions ...... 116 14.2 Option cost estimates ...... 118
Appendix A – Environmental Constraints Plan ...... 120
Appendix B – Safety Reports ...... 121 Accident Analysis – Links ...... 121 Accident Analysis – Junctions ...... 125
Appendix C – Original Offline Route Options ...... 129
Appendix D – Refined and Hybrid Offline Route Options ...... 130
Appendix E – Options Assessment Framework Tables ...... 131
- v - Project Support Framework (Consultancy) 2011 – 2016 A27 Chichester Bypass Technical Appraisal Report
15 References ...... 132
Tables
Table 1- A27 2013 Automatic Traffic Counts ...... 16
Table 2 Accident Selection Criteria ...... 17
Table 3 A27 accident totals by Link and Junction (Existing) ...... 18
Table 4 Rainfall levels ...... 21
Table 5 - C3 Estimates ...... 31
Table 6 – Population at risk on Highways England Roads...... 84
Table 7 – Option 1 Road Safety Review Comments ...... 85
Table 8 – Option 2 Road Safety Review Comments ...... 87
Table 9 – Option 11 Road Safety Review Comments ...... 88
Table 10 – Option 13 Road Safety Review Comments ...... 90
Table 11 – Option 15 Road Safety Review Comments ...... 92
Table 12 – Option 19 Road Safety Review Comments ...... 93
Table 13 – Option W Road Safety Review Comments ...... 95
Table 14 – Option X Road Safety Review Comments ...... 96
Table 15 Stakeholders Workshop meetings ...... 110
Table 16 A27 Focus Group meetings ...... 111
Table 17 - Objectives Scoring Summary...... 112
Table 18: Key project milestones ...... 113
Table 19: Option Cost Estimates ...... 118
Figures
Figure 2.1 Journey Time Reliability ...... 7
Figure 2.2 Network Performance 2012/13 – Peak Hour Speeds ...... 8
Figure 2.3 Network Performance 2012/13 – Delay ...... 9
Figure 2.4 Safety on the Network ...... 10
- vi - Project Support Framework (Consultancy) 2011 – 2016 A27 Chichester Bypass Technical Appraisal Report
Figure 2.5 Proposed New Homes and Jobs (to 2021) ...... 12
Figure 3.1 Chichester Area Road Network ...... 15
Figure 3.2 Rainfall levels ...... 21
Figure 3.3 Rainfall intensities ...... 22
Figure 5.1: Proposed Through-about ‘Hamburger’ layout at Fishbourne Roundabout ...... 38
Figure 5.2: Proposed Grade Separated Junction at Fishbourne ...... 39
Figure 5.3: Proposed Grade Separated Junction at Fishbourne with Stockbridge Link ..... 40
Figure 5.4: Proposed Signalised Full-Movement Crossroads ...... 41
Figure 5.5: Proposed Signalised Crossroads with Banned Right Turns ...... 42
Figure 5.6: Removal of Stockbridge Junction ...... 43
Figure 5.7: Proposed Signalised Full-Movement Crossroads ...... 44
Figure 5.8: Proposed Signalised Crossroads with Banned Right Turns ...... 45
Figure 5.9: Removal of Whyke Junction ...... 46
Figure 5.10: Proposed Signalised Full-Movement Crossroads ...... 47
Figure 5.11: Proposed Grade Separated Junction ...... 47
Figure 5.12: Existing Oving Junction ...... 48
Figure 5.13: Proposed Signalised Crossroads with Banned Right Turns ...... 49
Figure 5.14: Crossroads as Section 278 Developer Design ...... 49
Figure 5.15: Existing Portfield Junction ...... 50
Figure 5.16: Proposed Additional Lanes on Westbound Approach ...... 51
Figure 5.17: Additional Lanes on Circulatory Carriageway ...... 51
Figure 5.18: Stockbridge Link Road and Extension ...... 52
Figure 5.19 Route A Location Plan ...... 57
Figure 5.20 Route B Location Plan ...... 60
Figure 5.21 Route C Location Plan ...... 62
Figure 5.22 Route D Location Plan ...... 64
- vii - Project Support Framework (Consultancy) 2011 – 2016 A27 Chichester Bypass Technical Appraisal Report
Figure 5.23 Route E Location Plan ...... 65
Figure 5.24 Route F Location Plan ...... 67
Figure 5.25 Route G Location Plan ...... 68
Figure 5.26 Route H Location Plan ...... 69
Figure 5.27 Route J Location Plan ...... 70
- viii - Project Support Framework (Consultancy) 2011 – 2016 A27 Chichester Bypass Technical Appraisal Report
Executive Summary
The existing A27 Chichester Bypass is an approximately 5.0km length of dual carriageway located at the South of Chichester in West Sussex with six at-grade junctions: Fishbourne, Stockbridge, Whyke, Bognor, Oving and Portfield. A schematic location plan is included below.
In the wider context, the A27 forms part of the Honiton (in Devon) to Folkestone (in Kent) Trunk Road along the south coast. The overall route is of varying standards. To the west of Chichester, it is a dual carriageway with grade-separated junctions, with a section of motorway (M27) between Portsmouth and Southampton followed by the A31. To the immediate east of Chichester, the A27 Westhampnett Bypass is a modern standard dual carriageway with a grade-separated junction with A285, although then an at-grade junction is present in Tangmere immediately afterwards. To the East of Tangmere, route alternates between single and dual carriageway standards until Pevensey where it forms the A259.
The largest challenge currently affecting the existing Chichester Bypass is the level of congestion at key junctions, leading to long journeys and poor journey time reliability. These challenges are further exacerbated during the seasonal peaks and during events at the nearby Goodwood estate due to the high tourism draw to the area. According to DfT data from November 2014, the section of bypass between Bognor Road and Portfield roundabouts ranks 63rd worst out of 2,497 road links across the country and the opposing direction ranking 73rd worst for Journey Time Reliability. The route also has a high accident rate (ranked in the top 50 nationally (10, 27, and 31 out of 250 national
Page 1 of 132 Project Support Framework (Consultancy) 2011 – 2016 A27 Chichester Bypass Technical Appraisal Report locations.), in part due to the close junction spacing along the length of the existing Chichester Bypass.
As well as the congestion challenge, any improvement solution needs to consider the close proximity of properties and businesses to the Bypass, some with direct access / egress facilities to the carriageway. This is a key constraint in terms of built environment in addition to the many related to the natural environment detailed later on.
Highways England and Mott MacDonald Grontmij (MMG) alongside input from key stakeholders including West Sussex County Council and Chichester District Council have developed a number of key project specific objectives to act as performance criterion in the sifting of proposed highway improvement options. Objectives derived include the following:
° Reduce Congestion on the Chichester Bypass ° Improving Road Safety during Construction, Operation and Maintenance ° Reducing adverse environmental impacts and eliminate where possible ° Improve Journey reliability on the Strategic Road Network (SRN) ° Give Consideration to Buildability ° Improve capacity and support the growth of regional economies ° Tackling Climate Change ° Mitigating the impacts of congestion and manage traffic flows on the local road network ° Maintain and improve connection of areas by footpaths and cycle paths ° Take account of the potential future need for a park and ride site on the eastern and western approaches to the city ° Ensure provision for access to new housing
In identifying the project objectives, the approach taken was to follow the guidance offered by the Department for Transport’s (DfT), Transport Analysis Guidance (TAG). To this extent, the stakeholders mentioned above, first identified the current and future problems and challenges related to the A27 at Chichester in the context of national, regional and local policies. The debate concluded that there was a ‘need’ for substantial intervention to address the problems identified and meet the objectives Options Identification
A total of 17 highway options have been identified in Stage 1 – Options Development as part of this project with the view to incorporate measures and interventions that are likely to address the objectives established. These options fall broadly in to three categories:
° Online junction improvements along the existing Chichester Bypass corridor; ° New offline bypasses to the North or South of Chichester; ° Hybrid options consisting of online junction improvements to some of the six existing junctions with partial offline alignments that can bypass the reminder.
These options have been sifted to a short-list in accordance with the Department for Transport’s Transport Analysis Guidance (TAG) – The Transport Appraisal Process. A
Page 2 of 132 Project Support Framework (Consultancy) 2011 – 2016 A27 Chichester Bypass Technical Appraisal Report number of public transport options have also been considered as part of the Stage 1 process in addition to the road based ones listed above.
Appraisal Approach
In accordance with the Department for Transport’s TAG, the nine-step approach was followed to appraise the options generated. In this approach we have carried out an initial assessment and sift of the options (Step 6), followed by a further development and assessment of the options (Step 7) including assessing these against the project objectives.
After the options were generated they have been sifted to identify the better performing options. The aim of the sift was first to identify at a high level, any obvious option outliers that had been proposed during the option generation stage but that had generally failed to meet the outline criteria of EAST (Early Assessment and Sifting Tool from DfT) with regards to a strategic, economic, environmental or social context. Then, in support of EAST, a detailed analysis was undertaken to score the performance of each option against the project specific objectives using a 5 point system and identify the best performing options for further consideration. Results of Options Sifting Process
From the sifting process, Option 19, Route E, Option G and Option J were identified as the least performing options. Option 19 – an online improvement option, despite indication good value for money, appears to fail to address congestion by 2029 with some junctions even operating at capacity in 2014. Route E – a complete offline route to the south on Chichester, Option G – a hybrid option combining online improvements to some junctions , followed by an offline segment to the south of Chichester and Option J – another hybrid option but with more extensive offline construction, scored moderately well against congestion and other associated issues. However, these had significant adverse environmental impacts due to their southerly route alignments and were considered to be of poor value for money due to the high capital costs incurred through the difficult ground conditions to the south of Chichester.
These options have been discounted in Step 6 of the appraisal. Other options have also been discounted in Step 7 – Development and Assessment of Potential Options on the basis that they were presenting very similar components. Where this was the case, the options indicating inferior performance were discounted. This aspect is detailed further in the Options Assessment Report 343538-09-010-RE-003.Conclusions
The results of the sifting process show that the following options are identified as the better performing options when assessed against both the EAST criteria and the specific project objectives, therefore it is considered these are worthy of further consideration and as such will be taken forward to the WebTAG Stage 2 – Further Appraisal process for further consideration:
° Route B – offline bypass route to the north of Chichester.
Page 3 of 132
Project Support Framework (Consultancy) 2011 – 2016 A27 Chichester Bypass Technical Appraisal Report
1 Introduction
Junction improvements along the existing Chichester Bypass were initially proposed as part of the South Coast Multimodal Study (SoCoMMS) in 2000. Since then a number of schemes have investigated solutions to the congestion present along this section of road, including a Public Consultation in 2005, but to date no major improvements have been delivered. A more detailed history of the scheme can be found in the Options Appraisal Report, 343538-09-010-RE-003.
Mott MacDonald Grontmij (MMG) has been appointed by Highways England to review the previous studies, including all online options and offline routes. MMG are to determine if they are still viable options capable of catering for traffic levels in 2034, the updated design year, and carry a short-list of options through to the end of Project Control Framework (PCF) Stage 2. In addition to assessing the previous options the study is to re-establish the scheme objectives, which are described in the Client Scheme Requirements (CSR). The assessment of the options shall be carried out as detailed in the Options Appraisal Report, 343538-09-010-RE-003.
Page 5 of 132 Project Support Framework (Consultancy) 2011 – 2016 A27 Chichester Bypass Technical Appraisal Report
2 Planning Brief 2.1 Project Objectives
The Aims and Objectives for this scheme can be found in the Client Scheme Requirements, 343538-90-010-RE-001. The Transport Objectives listed in that document are as follows; • Reduce congestion on the Chichester Bypass • Improve road safety, during construction, operation and maintenance for all, as defined in DMRB Volume 0 Section 2 Part 3 GD 04/12: o Road workers o Road users o Other parties • Reduce adverse environmental impacts & eliminate where possible o Address existing Air Quality Management Areas (AQMAs) and ensure no further AQMAs are created as a result of selected option o Address existing noise important areas and ensure no further noise important areas as a result of selected option • Improve journey time reliability on the Strategic Road Network (SRN). • Improve capacity and support the growth of regional economies o Facilitate timely delivery of the scheme to enable provision of housing demand in line with the Chichester Local Plan o Improve regional connectivity o Improve accessibility to areas with tourist activity
Other Objectives identified between Highways England and Local Authorities have been identified as;
• Consider buildability, to ensure the design: o Facilitates ease of construction within the scheme / land constraints o Minimises disruption to road users and local residents from construction activities o Facilitates practical traffic management solutions during construction
Regional Objectives - West Sussex County Council (WSCC) • Tackling Climate Change • Promoting economic growth • Improving Safety, Health and Security • Improving Accessibility
Local Objectives - (Chichester District Council (CDC) • Mitigating the impacts of congestion and manage traffic flows, especially on A27 • Encourage and support opportunities for businesses. • Ensure provision for access to new housing • Encourage and support opportunities for businesses. • Improve transport links to support and encourage tourism. • Maintain and improve connection of areas by footpaths and cycle paths • Conserve and enhance the historic landscape and natural environment
Page 6 of 132 Project Support Framework (Consultancy) 2011 – 2016 A27 Chichester Bypass Technical Appraisal Report
• Take account of the potential future need for a park and ride site on the eastern and western approaches to the city
2.2 Understanding the Current Situation
2.2.1 Operational and Capacity Situation
Junction improvements have been proposed on the Chichester Bypass since the original SoCoMMS study was announced in 2000. Since then the traffic levels on the bypass have increased by 12%1. This figure did decrease between 2007 and 2011 with the recession, but has since returned to the pre-recession levels. The traffic levels on the SRN are predicted to rise by between 23.6% and 71.8% higher than 2010 levels by 20402.
The Journey Time Reliability (JTR), shown in Figure 2.1, shows a fall from 65.0% to 59.6% over the period of March 2011 to September 2014 for the A27 links, compared to 75.5% to 75.2% over the same period nationally3. Of particular note is the link between Bognor Road and Portfield roundabouts ranking 63rd worst out of 2,497 road links across the country and the opposing direction ranking 73rd worst. These figures clearly point to a worsening of the existing conditions, which regularly sees extensive queuing during peak periods.
Figure 2.1 Journey Time Reliability
1 Data retrieved from http://www.dft.gov.uk/traffic-flows in May 2015 for the Havant to Chichester, Fishbourne to Stockbridge and Portfield to A285 links comparing 2000 to 2013 traffic levels. 2 DfT National Transport Model analysis, https://www.gov.uk/government/uploads/system/uploads/attachment data/file/212474/road-transport- forecasts-2013.pdf 3 Data retrieved from https://www.gov.uk/government/statistical-data-sets/cgn01-journeys-on-time-ha- motorways-and-a-roads DfT Table CGN0106, last updated 13 November 2014
Page 7 of 132
Project Support Framework (Consultancy) 2011 – 2016 A27 Chichester Bypass Technical Appraisal Report
2.2.3 Social and Environmental Situation
The existing A27 Chichester Bypass faces a number of environmental constraints, as presented in Appendix A – Environmental Constraints Plan. Of these, the key challenges facing the scheme are the Air Quality Management Area (AQMA) at Stockbridge, the historic flooding problems and surrounding flood plains, and the separation the A27 causes between Chichester and the Manhood Peninsula.
The AQMA is of particular concern as the current traffic congestion contributes to the poor air quality, and so this location is very sensitive to any improvements. If air quality modelling indicates the proposed improvements would worsen the current situation this could well prevent the scheme from going forwards. Additionally this could be an opportunity to improve the air quality and so health of the residents living within this area.
The flooding problems along the Chichester Bypass have caused significant problems in the past, although following a meeting with the BBMM Area 4 maintenance team on the 11th of February 2015 they informed us these have mostly been addressed with new pumps at Whyke and Portfield to prevent the carriageway from flooding.
The Chichester Bypass currently acts as a boundary between Chichester and the Manhood Peninsula to the south. Whilst there are non-motorised user (NMU) crossing points at Stockbridge and Bognor Road, with a new bridge being constructed at Whyke, the carriageway still forms a barrier. The challenge this presents is that the scheme must be mindful not to increase the separation, or through the increase of free-flowing traffic and increased NMU facilities the opportunity to improve access across the carriageway.
2.3 Understanding the Future Situation
A capacity assessment of the existing junction layouts shows that Fishbourne, Stockbridge, Whyke and Bognor Road junctions are all over capacity even with 2014 traffic, Oving Road reaches capacity before 2029, and Portfield reaches capacity between 2029 and 2034.
As highlighted in Figure 2.5, a large number of homes are scheduled for construction, with 2,450 homes in Chichester by 2021 and over 6,900 by 2029. The plan below also shows 15,280 new homes are due to be constructed by 2021 and 12,399 new jobs created in the Arun District, which borders Chichester and notably includes Bognor Regis (connected to the SRN and the A27 by the A259 at the Bognor Road Roundabout), Littlehampton and Angmering. These will only place further strain on the road network and further increase the congestion around Chichester.
Page 11 of 132
Project Support Framework (Consultancy) 2011 – 2016 A27 Chichester Bypass Technical Appraisal Report
Southampton (and the ports there), as well as other locations to the West, and locations to the East such as Worthing, Brighton, Hastings and Eastbourne.
The six junctions on the Chichester Bypass are where the radial routes between the south coast (Manhood Peninsula and Bognor Regis) and the city centre cross the Chichester Bypass, and junction spacing varies from 0.5km to 1.2km. The average annual daily traffic (AADT at 2013 level) on the links between junctions is in the order of 35-45,000 vehicles, below standard value for link capacity, which indicates that the current delays and queues are caused by insufficient junction capacities.
Although intended to act as a strategic route, in reality the majority of traffic using the bypass is formed of local trips accessing Chichester, particularly from the Manhood Peninsula to the south, and from the A259 (Bognor Regis). Only approximately 40% of traffic using the bypass is estimated to be through traffic.
It is therefore a combination of the close proximity of the junctions and the conflict between the competing north-south and east-west traffic flows that result in significant congestion and extensive queuing at most of the junctions at peak times, disrupting the mainline flow of the road and compromising its operation as a strategic route.
Other problems associated with congestion on the bypass include rat-running through residential areas, commercial areas and on minor roads, causing congestion through local villages.
The Chichester Local Plan (2014) identifies the need for over 6900 new homes in the city and the immediate area to be delivered by 2029. This large number of additional homes are likely to further exacerbate the problem, with the A27 being the closest strategic route to these developments but already having insufficient junction capacity.
It is therefore evident that due to congestion the Bypass acts as a deterrent and barrier to development in an around Chichester. Traffic delays are a major problem that needs to be addressed for current levels of traffic and to accommodate future traffic growth.
The above information clearly shows that a need for intervention is necessary.
Page 13 of 132 Project Support Framework (Consultancy) 2011 – 2016 A27 Chichester Bypass Technical Appraisal Report
3 Existing Conditions 3.1 Description of the Locality
3.1.1 The City of Chichester and District
The Chichester District is situated in the South East of England, within West Sussex, and is bordered by the counties of Hampshire and Surrey. The district is generally rural, with significant levels of arable farming taking place. The Chichester District covers an area of 78,632 hectares and covers a larger area than any other district in West Sussex
The City of Chichester is the only city in West Sussex and has historical importance, attracting large numbers of visitors each year. In terms of townscape, Chichester lies at the centre of an area called the 'South Coast Plain’. The character of the study area is that of an urban fringe in a flat landscape. On the southern, south-eastern and south-western fringe of Chichester, residential and light industrial development has expanded to meet the boundary formed by the bypass. Except for Chichester Harbour, the village of Fishbourne and the suburb of Stockbridge, the remaining landscape beyond the A27 to the south comprises flat farmland with large and medium sized fields enclosed by hedges.
Chichester has significant historical and cultural assets, including the Chichester Festival Theatre, Chichester Cathedral and the Goodwood Estate and Racecourse
The population of Chichester District was 113,794 as of 2011, which is split between 54,401 males and 59,393 females, which equates to 47.8% males and 52.2% females. (National split: 49.2% males and 50.8% females).
The largest age group in the district were people aged 45-59. Most notably, almost 1 in 4 people in the district are aged 65+ (24.4%) this is much higher than the national average (16.4%).
Chichester is in general a prosperous area with low levels of unemployment (2.7%), and high house prices (average £317,456). According to the “West Sussex Local Economic Assessment”, the total value of the economy as of 2007 was £2.41bn and the average weekly income was £360. The key industrial sectors of the Chichester District are agriculture, property and public administration.
Chichester is an established centre for business and a popular shopping destination with a range of independent retailers and high street stores. The City is also becoming a thriving place for students with a popular University and College, attracting students from across the country.
The area attracts a high number of tourists with its good quality beaches and leisure facilities.
Page 14 of 132 Project Support Framework (Consultancy) 2011 – 2016 A27 Chichester Bypass Technical Appraisal Report
3.1.2 A27 Chichester Bypass
The existing A27 Chichester Bypass is part of the Ashford to Honiton Trunk Road along the south coast. The route is of varying standard. Around Chichester, it is a dual carriageway (D2AP) approximately 5km long with at-grade roundabouts at Fishbourne Road (A259), Stockbridge Road (A286), Whyke Road (B2145), Bognor Road (A259), and Portfield. There is a traffic signal controlled cross-road junction with Oving Road (B2144), located between Bognor Road and Portfield junctions.
To the west of Chichester, it is a dual carriageway with grade-separated junctions, with a section of motorway (M27) between Portsmouth and Southampton followed by the A31. To the immediate east of Chichester, the A27 Westhampnett Bypass is a modern standard dual carriageway with grade-separated junction, although an at-grade junction is present in Tangmere. Further east but still within West Sussex the A27 remains dual carriageway standard with at-grade junctions. The only exception to this standard is at Arundel and Worthing, where it is predominantly single carriageway. The road network in the Chichester area is shown in Figure 3.1.
The Chichester Bypass performs two important functions. Firstly, as part of the south coast trunk road (Ashford-Honiton), it provides for strategic, east-west traffic movements. Secondly, by its location it also provides for local movements, including traffic from the coastal belt (areas such as the Witterings and Bognor) that wishes to access Chichester. Local traffic from the A259 Bournes corridor to the west, the Manhood Peninsular to the south and the Greater Bognor area to the south-east all use the bypass to access Chichester or beyond. Traffic along the A259 corridor shares the A27 section of the bypass between Bognor Road and Fishbourne Roundabout.
Figure 3.1 Chichester Area Road Network
Page 15 of 132
Project Support Framework (Consultancy) 2011 – 2016 A27 Chichester Bypass Technical Appraisal Report
3.3.3 Journey Time Reliability
The existing Chichester Bypass has a lower level of Journey Time Reliability (JTR) than other A Roads on the Strategic Road Network, with an average JTR of 62.0% compared to that of 74.7% on the SRN as a whole between 2013 and 2014.
Reliability in this context is defined as variation in journey times that transport users are unable to predict, and measurements of the monetised journey time reliability benefits from a scheme proposal should be based solely on the unpredictable variation, because of the extra costs incurred by travellers.
In order to assess the journey time reliability benefits of the scheme, and to follow the latest WebTAG guidance, we propose that MyRIAD is used.
There are two sources of journey time reliability benefits. The first is related to reduced queuing at incidents (accidents specifically) and is therefore referred to as incident-related variability (IRV). The second is referred to as day to day variability (DTDV).
MyRIAD uses a simple link based network that is developed from select link analysis undertaken within the traffic model. It takes AADT traffic flows from the model and uses standard economic parameters such as incident frequencies published by the DfT to calculate the change in IRV and DTDV between the future year Do-Minimum and Do- Something scenarios.
3.4 Topography, Land Use, Property and Industry
3.4.1 Topography
The topography of the scheme area is generally subdued and gently undulating. Ground levels in the wider area reach a maximum of approximately 25m Above Ordnance Datum (AOD). In the immediate vicinity of the scheme, ground levels rarely rise above 10m AOD and become lower towards the coast and the Chichester Channel. The existing Chichester Bypass approximately follows the 10m contour. To the south of the study area, the land is low lying and forms marshland and mudflats. At Mile Pond, to the south of Stockbridge, ground levels are approximately 7m AOD.
The River Lavant runs through the study area from north to south, towards the Chichester Channel, and the Chichester Canal flows to the south past Stockbridge.
3.4.2 Land Use, Property and Industry
The city of Chichester forms the main area of land in urban use north of the existing Chichester Bypass with the land in close proximity being mainly residential. Stockbridge and Fishbourne form the main urban areas south of the existing Chichester Bypass.
Most of the land south of the existing Chichester Bypass between Whyke and Fishbourne Junctions is used for agricultural purposes which consist mainly of arable and some livestock farming. According to information from the Agricultural Land Classification for
Page 19 of 132 Project Support Framework (Consultancy) 2011 – 2016 A27 Chichester Bypass Technical Appraisal Report
England and Wales, South East Region, the agricultural land is mostly of grade one and two (‘excellent’ and ‘very good’) quality.
Land east of the existing Chichester Bypass between Portfield and Bognor Road Junctions is predominantly in industrial use. Gravel extraction is the main activity, and as a result, a number of lakes have been formed which are important for wintering birds. The gravel extraction site between Shopwhyke Road and the existing Chichester Bypass is currently under residential development with the first houses planned for construction in 2015.
There are a number of retail parks and light industrial uses mixed in with the residential areas adjacent to the existing Chichester Bypass. These include Chichester Gate Leisure Park to the north of Stockbridge Junction and Portfield Retail Park adjacent to Portfield Junction.
The Manhood Peninsula is accessed primarily via the existing Chichester Bypass, using the junction at Stockbridge for East and West Wittering, and Whyke for Selsey. West Wittering has a high tourism draw, with the West Wittering Estate reporting approximately 150,000 cars visiting per year (an 11% rise since 2001)6. They estimate that the average number of visitors per car is three and that 63% of visitors travel by car to reach the area. This leads us to a total of 450,000 visitors by car to West Wittering each year, compared to a total by all modes of transport of 715,000 visitors to West Wittering and 1,360,500 for the Chichester Harbour Area of Outstanding Natural Beauty overall. The average day trip expenditure per person is estimated to be £32 so the total expenditure from these car visitors to West Wittering is estimated at £14.4 million per year.
3.5 Climate
Chichester experiences an oceanic climate, with cool summers (highs of 21°C) and mild winters (highs of 9°C), with an average of 24 day of air frost per year.
Average annual rainfall is 725mm, ranging from a low of 40.9mm per month in the summer to a high of 91.9mm for October. This is lower than the UK annual average of 1373mm, with a summer low of 70mm and a winter high of 127mm. Table 4 and Figure 3.2 compare Chichester rainfall levels to the UK average. It is clear that Chichester’s monthly rainfall is representative of the wider UK distribution; however Chichester receives approximately 37% less rainfall than the UK.
6 UE Associates “Valuing Chichester Harbour” report 2009
Page 20 of 132
Project Support Framework (Consultancy) 2011 – 2016 A27 Chichester Bypass Technical Appraisal Report
Figure 3.3 Rainfall intensities
3.6 Drainage
3.6.1 Existing Situation
The existing drainage network along the A27 consists for the most part of concrete channel and gullies along the central reserve and near-side carriageway edges.
A meeting was held with the Area 4 maintenance team on 11th February 2015 and they reported the following considerations/issues:
Page 22 of 132 Project Support Framework (Consultancy) 2011 – 2016 A27 Chichester Bypass Technical Appraisal Report
• There is a significant history of carriageway flooding along the existing Chichester Bypass, in particular between the Portfield roundabout and the A285 to Halnaker. Between 2012 and 2014 the eastbound carriageway has flooded four times. • Bognor Road junction still has some flooding problems in the offside lanes on the Northern side of the roundabout. The A259 and Quarry Lane suffer similarly (adjoining/adjacent roads), indicating this area is potentially susceptible to flooding. Maintenance teams believe there could be a silted-up balancing pond in the vicinity that is causing this problem. • There are a large number of bodies of water that have historically been used as outfalls/balancing ponds, however they have increasingly found that local land owners have seen fit to populate them with fish which severely limits maintaining them as they would then be classed as habitats. Any future balancing ponds would need to address this somehow, either through legal protection or physical, to ensure that the effectiveness of the ponds is not reduced. • Some of the existing Chichester Bypass culverts and channels outfall into ditches to the south that should be maintained by the riparian land owner. There seems to be a common problem that land owners do not understand their riparian duties and as such these ditches block causing the drainage system to back-up. • V-Channels are good in principle but the existing channels don’t seem to self-clean due to shallow falls. • French drains are not favoured because unless maintained regularly they silt up and self-seeding plants take hold to further reduce drainage and can present an impact hazard if the situation is further neglected. • Ditches often end up being classed as habitats which restricts the work that can be carried out to maintain them.
In an attempt to address some of these issues, a new pump was installed at Shopwyke Park to take water away from the A27 between Portfield and the A285 to the Chichester flood relief channel. The Area 4 team state the pump is working well and has to-date, stopped incidents of flooding problems adjacent to Shopwyke and Portfield.
3.6.2 Proposed Drainage
Due to the early stage of the project, a detailed drainage design has not been undertaken however, a Highway Catchment Assessment has been carried out to initially identify potential outfalls and any required attenuation.
During Stage 2 a drainage design will be developed in more detail on the short list of options.
The as-built information for the existing drainage along the existing Chichester Bypass has been requested. Once received, this will be reviewed to inform the design strategy for drainage in the next phase.
Page 23 of 132 Project Support Framework (Consultancy) 2011 – 2016 A27 Chichester Bypass Technical Appraisal Report
3.7 Geology
British Geological Survey (BGS) online mapping7 has been utilised to determine the anticipated geology underlying the Scheme with BGS description in italics. The superficial geology comprises of the following:
• Head Deposits - Sand, Silt and Clay: “Polymict deposit: comprises gravel, sand and clay depending on upslope source and distance from source. Poorly sorted and poorly stratified deposits formed mostly from solifluction and/or hillwash and soil creep”. • River Terrace Deposits (Undifferentiated) - Sand, Silt and Clay: “Sand and gravel, locally with lenses of silt, clay or peat. [Generic description]”. • Alluvial Fan Deposits - Gravel, Sand, Silt and Clay: “Alluvium with a low-angle cone form, developed at the mouths of tributary valleys [generic description]… very localised source”. • Alluvium - Clay, Silt, Sand and Gravel: “Normally soft to firm consolidated, compressible silty clay, but can contain layers of silt, sand, peat and basal gravel. A stronger, desiccated surface zone may be present. [Generic description]”. • Raised Beach Deposits, 2 - Gravel: “Gravel and rarely sand; commonly with bank- like form”. • Raised Marine Deposits - Clay, Silt, Sand and Gravel: “Variable lithology. Gravel (shingle), sand, silt and clay; commonly charged with organic debris (plan and shell); now above the level of the present shoreline as a result of earth movement of a general fall in sea level. [Generic description]”.
It is anticipated that the following bedrock geology will be encountered for all proposed routes:
• London Clay Formation - Clay, Silt and Sand: “The London Clay mainly comprises bioturbated or poorly laminated, blue-grey or grey-brown, slightly calcareous, silty to very silty clay, clayey silt and sometimes silt, with some layers of sandy clay. It commonly contains thin courses of carbonate concretions (‘cementstone nodules’) and disseminated pyrite. It also includes a few thin beds of shells and fine sand partings or pockets of sand, which commonly increase towards the base and towards the top of the formation. At the base, and at some other levels, thin beds of black rounded flint gravel occur in places. Glauconite is present in some of the sands and in some clay beds, and white mica occurs at some levels”. • Lambeth Group - Clay, Silt, Sand and Gravel: “vertically and laterally variable sequences mainly of clay, some silty or sandy, with some sands and gravels, minor limestones and lignites and occasional sandstone and conglomerate”. • Lewes Nodular Chalk Formation, Seaford Chalk Formation, Newhaven Chalk Formation, Culver Chalk Formation - of the White Chalk Subgroup.
7 BGS Geology of Britain Viewer: http://mapapps.bgs.ac.uk/geologyofbritain/home.html , accessed November 2014
Page 24 of 132 Project Support Framework (Consultancy) 2011 – 2016 A27 Chichester Bypass Technical Appraisal Report
3.7.1 Geology along the existing Chichester Bypass
Modification works to the existing Chichester Bypass west of the city are anticipated to encounter superficial deposits of predominantly Head Deposits and River Terrace Deposits. Localised deposits of Alluvium, Alluvial Fan Deposits and Raised Marine Deposits could also be encountered. The superficial deposits are underlain predominantly by London Clay Formation, passing over Lambeth Group and Lewes Nodular Chalk Formation in the vicinity of Fishbourne.
River Terrace Deposits are predominately encountered at the Fishbourne Junction. At Stockbridge Junction Alluvial Fan and River Terrace Deposits are anticipated. Localised areas of Alluvium are also present. Both junctions are underlain by Lewes Nodular Chalk Formation.
In the eastern part of the Scheme, Alluvial Fan Deposits are predominately encountered at the Whyke, Bognor Road, Oving Road, and Portfield junctions. Head Deposits are recorded, outside the scheme area. Proximal to Tangmere, the route passes over Raised Storm Beach Deposits. The solid geology underlying the superficial material comprises predominantly London Clay Formation. The Lambeth Group is encountered in the vicinity of Whyke roundabout and to the south of the Scheme; Lambeth Group and Lewes Nodular Chalk Formation underlie the Raised Beach Deposits in the vicinity of Tangmere.
Areas of infilled ground and worked ground are also expected along the on-line works, particularly at the eastern extent of the scheme area.
3.7.2 Surrounding Geology
• North of Chichester, Superficial Geology. To the north it is anticipated that predominantly Head Deposits will be encountered. Alluvium deposits are present in association with the river valley of River Lavant. River Terrace Deposits may also be encountered, and at the eastern extent of any potential routes, Raised Storm Beach Deposits and Alluvial Fan Deposits may be encountered. • North of Chichester, Solid Geology. To the north it is anticipated to be underlain by London Clay Formation to the west, passing over successively older formations of the Lambeth Group and Lewes Nodular Chalk Formation towards the east. At the eastern extent there is likely to be geology of the Lambeth Group. • South of Chichester, Superficial Geology. To the north it is anticipated that predominantly Alluvial Fan Deposits and River Terrace Deposits will be encountered. Head Deposits and River Terrace Deposits are also anticipated. Small areas of Alluvium and Raised Marine Deposits may be encountered. • South of Chichester, Solid Geology. To the north it is anticipated to be underlain by a sequence of progressively younger geology towards the east: Lewes Nodular Chalk Formation, Lambeth Group and London Clay Formation. At the eastern extent Lambeth Group geology may be encountered again.
Areas of infilled ground and worked ground are to be expected in some areas due to widespread gravel extraction, particularly in the eastern part of the scheme area and predominantly associated with the south. Historical records obtained from the BGS
Page 25 of 132 Project Support Framework (Consultancy) 2011 – 2016 A27 Chichester Bypass Technical Appraisal Report website indicate that Made Ground depths associated with historic extraction works can exceed 10m bgl in some areas.
3.8 Mining
Historically, mining of the sand and gravel of the Raised Storm Beaches has occurred in the Chichester area. The BGS Mining Plans Portal8 and Coal Authority interactive mapping9 do not hold any records of mining for the scheme area.
A disused pit is noted on the Ordnance Survey (OS) map of the area at Westhampnett. The BGS Geoscience Data Index10 also notes a sand and gravel pit on the south side of the railway at Drayton House. This is not noted on the OS map, but there is a large regular shaped water body, which possibly indicates that there was once a quarry, which has subsequently flooded due to high groundwater surface. Similarly, gravel pits are marked at Shopwyke. These too are water filled and used for recreational water activities.
South of Portfield is a number of lakes. BGS records indicate artificial ground associated with these lakes. It is unknown whether these lakes are associated with historic mining.
It is anticipated that predominantly along the existing Chichester Bypass and to the south of Chichester areas of historic mining can be encountered
3.9 Accessibility
The public footpath and public rights of way around Chichester are extensive, with the original severance caused by the construction of the existing Chichester Bypass being mitigated by a number of Non-Motorised User crossings by the way of bridges at Stockbridge and Bognor Road junctions, with another under construction adjacent to Whyke junction. To the north of Chichester there is a bridleway and footpath along the path of a disused railway line, as well as numerous rights of way leading into the South Downs National Park.
The South Coast Cycle Route 2 is in close proximity to the existing Chichester Bypass, crossing it twice. Once is via a subway located to the west of Fishbourne roundabout, the second time via the Chichester Canal underpass. In addition to this, there are a number of cycle routes through Chichester, notably one linking Chichester to Bognor Regis along the A259. There are also cycle routes designated along the eastbound side of the existing Chichester Bypass between Stockbridge and Whyke junctions, and crossing the existing Chichester Bypass at Oving Road junction, which is a signal controlled crossroads.
3.10 Integration
Along with the existing Chichester Bypass running to the south of Chichester, there is a ring road system within Chichester utilising the A286. Chichester Railway Station is
8 BGS Mining Plans Portal: https://www.bgs.ac.uk/nocomico/choose search.htm, accessed December 2014 9 Coal Authority interactive mapping: http://mapapps2.bgs.ac.uk/coalauthority/home.html, accessed December 2014 10 BGS GeoIndex: http://mapapps2.bgs.ac.uk/geoindex/home.html, accessed December 2014
Page 26 of 132 Project Support Framework (Consultancy) 2011 – 2016 A27 Chichester Bypass Technical Appraisal Report managed by Southern and located just to the north of Stockbridge junction. In 2013/14 it served 3,269,044 trips11 and there are direct services to London Victoria (via Gatwick Airport), Brighton, Portsmouth and Southampton. There is a well-developed bus service, with routes to Bognor Regis, Portsmouth, Brighton, Petworth, East and West Wittering, Selsey and Tangmere.
3.11 Environment
The City of Chichester and the surrounding area are environmentally sensitive, with large areas of protected land and a number of listed buildings. Although it has an urban character, the Bypass and the study area are surrounded by a large number of ecological and environmental constraints including landscapes with multiple national and European designations, historic townscape, visual aspects and scheduled monuments, flood plains, key receptors, significant ecology habitat sites such as South Down National Park, etc. Important watercourses and waterbodies are also present in the study area, such as the Chichester Canal, Fishbourne Canal and the River Lavant as well as a number of lakes and ponds.
With the number and nature of the options considered, this information is extensively covered in Section 5.5.
3.12 Public Utilities
3.12.1 General
Following the development of the feasibility design, MMGJV undertook C2 inquires along the existing A27 Bypass corridor as well as areas to the north and south. The responses to the C2 inquiries are summarised in the Statutory Undertakers Estimate, 343538-90-200- ES-001.
A set of composite statutory undertakers’ equipment location plans has been produced which have been used in all stages of the design and have also been included within the target cost information.
The results of the C2 preliminary inquiry show that several undertakers have been highlighted as having equipment that may need diverting as a result of the proposed design options.
At present, C3 budgetary estimates have been obtained for only the design options considered along the existing A27 Bypass. The request was submitted based on the junction option with the greatest footprint to allow for a conservative budget estimate. Due to the large number of options with elements away from the existing corridor (i.e. offline options) at present, C3 estimates have been deferred until after the Stage 1 sifting process has been undertaken to reduce the number of unnecessary C3 requests. The outstanding C3 requests will be requested during Stage 2 once the number of offline options has been reduced.
11 Office of Road and Rail Figures, http://orr.gov.uk/statistics/published-stats/station-usage-estimates
Page 27 of 132 Project Support Framework (Consultancy) 2011 – 2016 A27 Chichester Bypass Technical Appraisal Report
Only statutory undertakers highlighted through the C2 process as having plant at each of the online junction locations were contacted further for C3 estimates. The C3 estimates were requested from the applicable statutory undertakers on the 8th December 2014 and were collected to form a full budgetary estimate at each junction. The responses to the C3 inquiries are summarised in the Statutory Undertakers Estimate, 343538-90-200-ES-001.
Below is a summary of equipment present at each of the existing Chichester Bypass junctions, with an assessment made as to the possible extent of diversion required to accommodate improvements.
3.12.2 Fishbourne Junction
A gas distribution depot is located to the north east corner of the junction meaning that a considerable number of other diversions may be required depending on the scale of works proposed at this junction. The most notable is a high pressure gas main which crosses the existing Chichester Bypass to the east of the junction, as well as a medium pressure main which runs along the centre of Cathedral Way. An additional gas diversion may also be required of a Low Pressure gas pipe which crosses the A27 to the west of Fishbourne Junction.
Comparatively less major utility works include the potential diversion of a Portsmouth Water main located to the west of the junction and a Southern Water sewer which crosses the A27 to the east of the junction which then crosses both Terminus Road and Cathedral Way.
Telecom utility services are present on the north and south of the roundabout, and cross the A27 to the west of the junction. Junction improvements may require alteration to the existing layout and reconstruction of a number of joint boxes.
High and low voltage electric cables run parallel to the A27 west of the junction and along Cathedral Way and Terminus Road. Street light cabling is also present on the current roundabout and A27 approaches, which may require diversion as part of the new junction lighting design.
3.12.3 Fishbourne to Stockbridge Link
Any widening of the link between Fishbourne and Stockbridge junctions may have an impact on gas, telecoms, electric, street lighting and water utilities.
The most significant diversion that may be required is the relocation of a High Pressure gas main that crosses the existing Chichester Bypass near to Fishbourne junction and runs parallel to the south of the route. A medium pressure gas main runs parallel along the northern verge, crossing the carriageway near Stockbridge junction.
BT underground telecoms cables run along the south of the existing Chichester Bypass with a single crossing point at the River Lavant. Due to the proximity of the carriageway any widening is likely to result in this cable requiring relocation.
Page 28 of 132 Project Support Framework (Consultancy) 2011 – 2016 A27 Chichester Bypass Technical Appraisal Report
Adjacent to Stockbridge junction, low voltage electrical and street lighting cables cross the carriageway. New ducting may need to be provided to accommodate any carriageway widening. Street lighting runs on both the north and south side of the carriageway for the entire length of the link.
3.12.4 Stockbridge Link Road (SLR)
The proposed SLR route corridor runs south east from Fishbourne junction to the A286 Birdham Road in Stockbridge. There are two significant utilities along this proposed route which may require diversion.
These are two high voltage electric cables, and a high pressure gas main, which run across the line of the proposed SLR route corridor.
Alterations may be required for three sewers, one that crosses the route at Fishbourne Junction, the second that crosses approximately half way along the route and the third runs along Birdham Road. Minor telecom diversions are also required where the link road ties in with Birdham Road and Fishbourne Junction. Other diversions where the link joins Birdham Road include low voltage electric cables, low pressure gas and a water main.
At a late stage in the design a proposal was put forward to extend this link road through to the B2145, outside the initial area of our consultation with Statutory Undertakers and with too little time to consult further. If an option is taken forward which includes this link road then further investigation will need to be carried out in the next stage.
3.12.5 Stockbridge Junction
There are a large number of utilities that travel along Stockbridge Road, passing north/south across the junction. These include two sewers, mains water, low and high voltage electric cables and BT underground telecoms cables.
A large number of utilities also run parallel to the existing Chichester Bypass on the approaches to this junction and may require diversion. On the north side there is street lighting, high voltage electric cable and a medium pressure gas main which crosses the junction. On the south side there is mains water, underground BT cables, low voltage electric cables and medium pressure gas.
To the east of the junction BT underground cables and low voltage electric cables cross the existing Chichester Bypass. The ducting for these may need to be extended to accommodate the proposed alterations in junction approach.
3.12.6 Whyke Junction
At the Whyke junction the existing known utilities are electric, water, telecoms and gas. Telecoms cables, water mains, low and high voltage electric cables cross the existing roundabout and may require diversion to allow for any alterations. A water main and a medium pressure gas main run on the south side of the existing Chichester Bypass and may also require diversion. Street lighting cables are also present, which will be moved as part of the new junction lighting design.
Page 29 of 132 Project Support Framework (Consultancy) 2011 – 2016 A27 Chichester Bypass Technical Appraisal Report
3.12.7 Bognor Road Junction
To the south of the junction several utilities cross the existing Chichester Bypass including high voltage electric cables, medium pressure gas and telecoms cables from BT, Virgin Media and SSE Telecoms. To the north of the junction a Virgin media cable crosses along the line of the railway.
Through the centre of Bognor junction BT telecoms, low voltage electrical cables and mains water cross the existing Chichester Bypass.
Along the western edge of the existing Chichester Bypass there are sewerage, low and high voltage electric cables, underground BT cables, Virgin Media cables and medium pressure gas pipes. Many of these utilities will require diverting in the event of any carriageway widening on the approaches to the junction. In addition, mains water, medium pressure gas, high and low voltage electric cables and Virgin Media telecoms are present on the eastern edge and may also require diversion.
3.12.8 Oving Junction
Utilities at this junction either cross along the line of Oving Road or follow the line of the A27 on the east or west verge. The utilities that cross in the line of Oving Road include sewers, mains water, low pressure gas, high and low voltage electric cables and BT underground cables.
Along the west verge of the A27 the utilities present include BT telecoms, high and low voltage electric cables, mains water and medium pressure gas. Along the east verge utilities include BT telecoms, mains water and low voltage electric cables. Also present at the junction is street lighting, these may need to be moved as part of the new junction lighting design.
3.12.9 Portfield Junction
Utilities present at Portfield Junction include; water mains, high and low voltage electric cables to the east and north of the junction and street lighting.
It is likely that any significant change in junction layout will result in diversions being required.
3.12.10 Summary of C3 Estimates
Table 5 below shows the provisional costs provided as a response to the C3 requests. Please see Statutory Undertakers Estimate, 343538-90-200-ES-001 for further details.
Page 30 of 132
Project Support Framework (Consultancy) 2011 – 2016 A27 Chichester Bypass Technical Appraisal Report
4 Planning Factors 4.1 Local Planning Policy
Current local policy guidance, relevant to the assessment of this proposal, is contained in the West Sussex Transport Plan 2011 to 202612 and the Chichester District Council Local Plan 2014 to 202913, which is currently under examination by the Secretary of State. The South East Plan was withdrawn in 2013 and so is not included in this document.
4.2 West Sussex Transport Plan
The summary of priorities for the West Sussex Transport Plan opens with “Improvements to the A27 trunk road and complementary public transport improvements to the current bottlenecks at Chichester…to increase capacity, improve reliability and safety and increase the competitiveness of local business and attract investment”.
The key topics covered in the plan are:
• Improved economy • Improving accessibility • Housing • Employment • Environmental sensitivity
Predicting a 5% increase in population over the first five years (2011 to 2016), the plan looks at traffic growth within the period and expresses concern that whilst some areas are already above capacity there may soon be more locations under real risk of being exceeding capacity, which would “have a detrimental effect on quality of life for our community”. The increase in population beyond 2016 is unclear, depending on the rate of new home construction, which in turn depends on improvements to the road network, in part around Chichester.
The listed objectives are;
• Promoting Economic Growth • Tackling Climate change • Improving Accessibility • Improving Safety, Health and Security
The section on the Strategic Road Network (SRN) describes the A27 as “the most unreliable all-purpose trunk road in England and experiences significant amounts of delay along the length of the route. In West Sussex, the most significant problems are at Chichester, Arundel, Worthing and Lancing where bottlenecks cause congestion, high
12 West Sussex Transport Plan, 2011 to 2026, https://www.westsussex.gov.uk/media/3042/west sussex transport plan 2011-2026 low res.pdf 13 Chichester Local Plan: Key Policies Pre-submission, 2014 to 2029, http://www.chichester.gov.uk/CHttpHandler.ashx?id=20516&p=0
Page 32 of 132 Project Support Framework (Consultancy) 2011 – 2016 A27 Chichester Bypass Technical Appraisal Report accident rates, severance and diversion onto unsuitable routes. The A27 fails to meet the current needs of the area which is also in need of regeneration in the coastal towns.” The plan then continues to describe the successive studies undertaken on the area and how specifically in Chichester the high level of local north-south traffic wishing to cross or join causes extensive congestion during peak periods, worsened by tourist traffic in the summer.
In the Implementation Plan section of the report they note that there is currently a good public transport network, but concerns over the cost and reliability due to congestion put many people off. The sections of the Implementation Plan relevant to the existing Chichester Bypass promote working with Highways England to secure improvements to the junctions on the route, developing Park and Ride sites (which could influence where bus-priority junctions are located) and encouraging HGVs to stay on the existing Chichester Bypass rather than diverting through local roads to save time.
4.3 Chichester District Council Local Plan
The Chichester District Council Local Plan is not currently finalised and is under examination by the Secretary of State and so the information below should be read with this in mind.
The key objectives listed in the plan are divided into four categories, with relevant objectives paraphrased below;
• Economy o Encourage and support opportunities for businesses, in locations with good access to the A27 o Improve transport links to support and encourage tourism • Housing and Neighbourhoods o Ensure provision for access to new housing • Environment o Conserve and enhance the historic landscape o Mitigate the impact on developments and reduce flood risks • Health and Well-Being o Maintain and improve connection of areas by footpaths and cycle paths • Strategic Infrastructure o Mitigating the impacts of congestion and manage traffic flows, especially on the A27 o Improve cycle routes and encourage public transport use o Ensure water resources are unaffected by potential impacts from developments.
In addition to the above points, the Local Plan describes the construction of approximately 3,000 houses in Shopwyke, West of Chichester City, Westhampnett and Tangmere developments, all within close proximity of adjacent to the existing Chichester Bypass. Whilst the intention is that these communities will be closely linked with Chichester by public transport, the ring-road nature of the current A27 Chichester Bypass will mean that
Page 33 of 132 Project Support Framework (Consultancy) 2011 – 2016 A27 Chichester Bypass Technical Appraisal Report those who will drive will likely put extra pressure on these junctions, worsening the existing situation. Over the area covered by the plan there are intended to be over 6,900 new homes.
4.4 Options Constraints
Constraint mapping has been undertaken and identified the following constraints:
• Environmental constraints: o Scheduled Monuments o Areas of water o Flooding o Geological constraints o Ancient woodland o Registered Common Land o Noise Important Areas o Air Quality Management Areas o RAMSAR o Nature Reserves o Parks and Gardens o South Downs National Park o Utilities o Conservation Areas
• Political constraints: o Listed buildings o Public Rights of Way o Planning applications o Strategic Development Areas o Areas of tourism
A constraints map has been produced and attached as Appendix A – Environmental Constraints Plan, and a Graphical Information System (GIS) created, called APOLLO. The APOLLO system allows users to view a map of the Chichester area and then overlay the proposed routes and different constraints. The client team within Highways England have been issued with individual log-in details.
In a summary of the constraints, to the north of the existing Chichester Bypass there are substantial areas of historic woodland, numerous listed buildings and the South Downs National Park. Adjacent to the River Lavant there is a small area that has a greater than 1% chance of fluvial flooding, but generally the flood risk is low to the north of Chichester.
To the south there are significant areas of flooding and bodies of water, such as the Chichester Canal, numerous lakes and Chichester Harbour, which is a designated a Ramsar site among other designations. In addition, adjacent to Fishbourne junction is the Fishbourne Roman Palace.
Page 34 of 132 Project Support Framework (Consultancy) 2011 – 2016 A27 Chichester Bypass Technical Appraisal Report
The existing Chichester Bypass corridor is very constrained due to the high level of development that lines the route. Adjacent to Fishbourne junction is a large Tesco superstore, and on the northern side of the link between Fishbourne and Stockbridge is an industrial estate. Stockbridge junction is a Noise Priority Area and an Air Quality Management Area (AQMA) and is closely surrounded by housing developments making any major alterations problematic. Whyke junction has Ivy Lake to the south east, housing developments to the north and farmland to the south west. The link between Stockbridge and Whyke is less constrained, with farmland to the south, however there is a petrol filling station on the eastbound carriageway.
Between Whyke and Bognor Road junctions, the link has a group of large lakes surrounding Chichester Lakeside Holiday Park to the south and to the north some housing and more lakes.
Bognor Road junction is very constrained on the eastbound side with a large industrial estate. On the westbound side there is currently little in the way of constraint, although it is understood that a retail development is proposed. It should also be noted that there is a road over rail bridge to the north of the Bognor Road junction which may require modification to accommodate any widening.
The link between the Bognor Road and Portfield junctions has housing on the eastbound side, and an old quarry on the westbound side. Oving cross-roads are also situated on this link.
Page 35 of 132 Project Support Framework (Consultancy) 2011 – 2016 A27 Chichester Bypass Technical Appraisal Report
5 Description of Route Options 5.1 Introduction
Following on from the Atkins review of the 2009 designs, Highways England has tasked the Mott MacDonald Grontmij JV with designing a solution to the problems discussed previously, taking account of the proposed housing developments in the Chichester and West Sussex local plan. Any proposed designs must also ensure the objectives from Highways England in the Client Scheme Requirements are fully considered.
In addition to the previous schemes, and further to the work done in 2005 by Bullen Consultants, there is now more interest in reviewing the potential for an offline route option. An offline option could help improve the flow of strategic traffic and increase the total distance along the South Coast without an at-grade junction. This currently extends between Woolsbridge Roundabout on the A31, through to Fishbourne Roundabout on the existing Chichester Bypass. The previously developed online options viewed it to be impractical to grade-separate all the junctions on the Chichester Bypass due to their close proximity and sub-standard weaving lengths, meaning that the only options to extend this distance are to either close several junctions, or construct an offline route.
A total of 17 proposed options have been generated, that broadly fall into the following three categories:
° Online junction improvements along the existing Chichester Bypass corridor; ° New offline bypasses to the North or South of Chichester; ° Hybrid options consisting of online junction improvements to some of the six existing junctions with partial offline alignments that can bypass the reminder junctions on the existing section.
All the options identified are presented in detail in the following sections.
5.2 Online Option Development
5.2.1 Online Options General Notes
During the previous study undertaken by Jacobs, four online options were identified (Options 11, 13, 15, & 19). Further works undertaken by West Sussex County Council and Chichester District Council have also been adopted by the development process as lower- cost options, and with minor amendments are known as Option W and Option X respectively.
As part of this new study, these previous options have been re-assessed with revised turning counts for 2034 traffic levels. In addition, two new online options have been considered (Options 1 & 2) and four new online/offline hybrid options have been proposed (Routes F, G, H & J), described in Section 0.
Page 36 of 132 Project Support Framework (Consultancy) 2011 – 2016 A27 Chichester Bypass Technical Appraisal Report
At present, each of the six junctions has been assessed for a variety of layouts allowing all six online and four hybrid options to be considered.
Turning count and queue length data from surveys conducted in November 2014 has been received from the Lot 5 provider, Jacobs. The AM and PM peak hour for each junction has been chosen based on total amount of traffic demand at the junction, calculated using the traffic passing through the junction and the maximum queued traffic. Queue lengths were converted from metres to Passenger Car Unit (PCU) assuming 6m per PCU.
In order to factor up the 2014 data to the design year of 2034, TEMPRO6.2 traffic growth for the Chichester local authority area has been used as this was higher than the West Sussex equivalent growth factor. Fuel and income factors from WebTAG data book (Nov 2014) have been applied.
The six junctions modelled were: • Fishbourne • Stockbridge • Whyke • Bognor • Oving • Portfield
5.2.2 Fishbourne Junction
Previous assessment work undertaken by Jacobs concluded that only a grade separated solution would work for the design traffic flows and as such, two options were presented by the Jacobs 2010 report. The first solution proposes the A27 as a flyover passing over the top of the existing roundabout. The second involves constructing a new roundabout above the current level of the A27 into which the existing roads will feed.
West Sussex County Council and Chichester District Council both proposed an at-grade, ‘hamburger’, or through-about solution.
As part of the new study, the following junction arrangements were tested for performance against the 2034 design year traffic: • At-grade – ‘hamburger’ arrangement • Grade-separated with Terminus Rd diverted onto the A259 N • Grade-separated as above but with the Stockbridge link-road attached
5.2.2.1. Through-about ‘Hamburger’ Junction
A through-about or ‘hamburger’ roundabout, shown in Figure 5.1, is a signalised cross- road / roundabout hybrid. The junction has the advantages of a cross-road in that mainline traffic can travel unhindered when a green signal is shown. However the junction has greater capacity than cross-roads, allowing vehicles to be stacked around the junction and controlled by signals.
Page 37 of 132 Project Support Framework (Consultancy) 2011 – 2016 A27 Chichester Bypass Technical Appraisal Report
A ‘hamburger’ junction is a low cost solution, involving the modification of the existing at- grade roundabout with the introduction of signals. However, this arrangement does not allow free-flow on the mainline all the time and modelling indicates that the ‘hamburger’ arrangement will provide capacity up to the year 2029, but will fail before the 2034 design year.
Figure 5.1: Proposed Through-about ‘Hamburger’ layout at Fishbourne Roundabout
5.2.2.2. Grade Separated Junction
A grade-separated, non-signalised junction was modelled for 2034 traffic volumes. This layout increases capacity by removing the mainline traffic from the junction and allowing it to flow un-hindered. This in-turn allows the side-road traffic to negotiate the junction without having to compete with the high volume main-line flow.
The layout below shows the mainline above the junction, however until the junction is modelled in 3D, the optimal arrangement will be unknown. Elevating the mainline over the junction typically consumes less land because the slips and circulatory carriageway are at- grade, although may reduce the stopping sight distance. A retaining structure is likely to be required between the mainline and the slips in order to reduce land-take. Provisional work indicates that due to the differences in design speeds, keeping the A27 at-grade and elevating the roundabout will reduce the visual intrusion and improve the practicality of the design.
Page 38 of 132 Project Support Framework (Consultancy) 2011 – 2016 A27 Chichester Bypass Technical Appraisal Report
The traffic model indicated that for this layout to work satisfactorily at 2034, Terminus Rd will need to be diverted onto the A259 as shown in Figure 5.2.
Figure 5.2: Proposed Grade Separated Junction at Fishbourne
Despite the advantages, it should be noted that a grade-separated solution will consume more land and cost substantially more to construct than an at-grade solution. In addition, there is likely to be significant disruption to the mainline traffic flow during construction. However, this type of junction typically provides the most capacity and in this case our preliminary modelling indicates it will operate successfully at the design year of 2034. 5.2.2.3. Grade Separated Junction with the Stockbridge Link Road
Parts of the online proposals being considered involve the restriction of movements at the Stockbridge and Whyke junctions. In order to facilitate this, a Stockbridge Link Road would be constructed to transfer these restricted movements to the Fishbourne junction, combined with the diversion of Terminus Road onto the A259N.
The layout below has been found to only work up until 2029, with the caveat that the redistribution of flows from banning movements will not be fully understood until analysis by the full traffic model has been undertaken. This arrangement is shown in Figure 5.3.
Page 39 of 132 Project Support Framework (Consultancy) 2011 – 2016 A27 Chichester Bypass Technical Appraisal Report
Figure 5.3: Proposed Grade Separated Junction at Fishbourne with Stockbridge Link
5.2.3 Stockbridge Junction
Stockbridge junction is currently a four arm at-grade roundabout between the existing Chichester Bypass and the A286. The previous 2009 study determined that signalising the existing roundabout was insufficient for improving through capacity on the existing Chichester Bypass, however shall be tested again to ensure this is the case.
The following junction arrangements have been tested for performance against the 2034 design year traffic: • At-grade signalised roundabout (current geometry) • Signalised full-movement crossroads • Signalised crossroads with banned right turns
Additionally an option has been put forward looking at removing the Stockbridge junction by constructing a grade separated arrangement (fly-over) with no link between the existing Chichester Bypass and the A286. Grade separation at this junction is not possible due to its proximity to Fishbourne Junction.
5.2.3.1. At-grade Signalised Roundabout
It was found that if the current arrangement were signalised it would still not provide adequate capacity for 2014 traffic, let alone for the design year 2034.
Page 40 of 132 Project Support Framework (Consultancy) 2011 – 2016 A27 Chichester Bypass Technical Appraisal Report
5.2.3.2. Signalised Full-Movement Crossroads
A signalised crossroad arrangement, as shown in Figure 5.4, allowing full movements was modelled for the design year of 2034. This arrangement was found to fail before 2029.
Figure 5.4: Proposed Signalised Full-Movement Crossroads
5.2.3.3. Signalised Crossroads with Banned Right Turns
A signalised crossroad arrangement, as shown in Figure 5.8, with banned right turns was modelled for the design year of 2034. This arrangement was found to work for 2034, with some congestion. It should be noted that the impact of relocated traffic by banning right turns has not been accounted for at this stage. This will be part of the work during Stage 2 once the full traffic model has been completed.
Page 41 of 132 Project Support Framework (Consultancy) 2011 – 2016 A27 Chichester Bypass Technical Appraisal Report
Figure 5.5: Proposed Signalised Crossroads with Banned Right Turns
5.2.3.4. Removal of Stockbridge Junction
This arrangement would have the existing Chichester Bypass passing over the A286 with no connection between the two roads. This will allow the two straight across movements to occur unhindered, but has the disadvantage of not allowing any link (and therefore turning movement) between the two roads.
It has been decided to propose to elevate the mainline as opposed to the A286 because it would be difficult to maintain access to the number of properties that line the A286 if this was elevated.
This arrangement has not been modelled as part of this review, but the proposal will be modelled when the wider traffic model is ready. It is important to note that the impact of removing the turning ability at this junction will not be fully understood until the full traffic model is available, however it has been assumed this modification would be introduced with the Stockbridge Link Road transferring these movements to the Fishbourne and Bognor Road junctions.
Page 42 of 132 Project Support Framework (Consultancy) 2011 – 2016 A27 Chichester Bypass Technical Appraisal Report
Figure 5.6: Removal of Stockbridge Junction
5.2.4 Whyke Junction
Whyke junction is currently a four-arm at-grade roundabout at the intersection of the existing Chichester Bypass and the B2145 Whyke Road. The previous 2009 study determined that signalising the existing roundabout was insufficient for improving through capacity on the existing Chichester Bypass, however shall be tested again to ensure this is the case.
The following junction arrangements were tested for performance against the 2034 design year traffic: • At-grade signalised roundabout (current geometry) • Signalised full-movement crossroads • Signalised crossroads with banned right turns
Additionally an option has been put forward looking at removing the Whyke junction by constructing a grade separated arrangement (fly-over) with no link between the existing Chichester Bypass and the B2145. Grade separation is not possible at this junction due to its proximity to Bognor Road junction.
5.2.4.1. At-grade Signalised Roundabout
It was found that if the current arrangement were signalised it would still not provide adequate capacity for 2014 traffic, let alone for the design year of 2034.
Page 43 of 132 Project Support Framework (Consultancy) 2011 – 2016 A27 Chichester Bypass Technical Appraisal Report
5.2.4.2. Signalised Full-Movement Crossroads
A signalised crossroad arrangement, shown in Figure 5.7, allowing full movements was modelled for the design year of 2034. This arrangement was found to fail before 2029.
Figure 5.7: Proposed Signalised Full-Movement Crossroads
5.2.4.3. Signalised Crossroads with Banned Right Turns
A signalised crossroad arrangement with banned right turns was modelled for the design year of 2034. This arrangement was found to work for 2034, with some congestion. It should be noted that the impact of relocated traffic by banning right turns has not been accounted for at this stage. This will be part of the work during Stage 2 once the full traffic model has been completed.
Page 44 of 132 Project Support Framework (Consultancy) 2011 – 2016 A27 Chichester Bypass Technical Appraisal Report
Figure 5.8: Proposed Signalised Crossroads with Banned Right Turns
5.2.4.4. Removal of Whyke Junction
Here the existing Chichester Bypass would pass over the B2145 with no connection between the two roads. This arrangement allows the two straight across movements to occur unhindered, but has the disadvantage of not allowing any link between the two roads.
In a similar manner to the Stockbridge junction, it has been proposed to elevate the mainline and not the side road. This is because elevating the side road will be problematic due to the number of adjoining properties and access roads.
It is proposed to elevate the B2145 as opposed to the A27 because there appears to be sufficient space to elevate the side road, and this will help maintain a high quality alignment for the A27.
This arrangement has not been modelled as part of this review, but the proposal will be modelled when the wider traffic model is ready. It is important to note that the impact of removing the turning ability at this junction will not be fully understood until the full traffic model is available, however it has been assumed this modification would be introduced with the Stockbridge Link Road transferring these movements to the Fishbourne and Bognor Road junctions.
Page 45 of 132 Project Support Framework (Consultancy) 2011 – 2016 A27 Chichester Bypass Technical Appraisal Report
Figure 5.9: Removal of Whyke Junction
5.2.5 Bognor Road Junction
Bognor Road junction is currently a five-arm at-grade roundabout at the intersection of the existing Chichester Bypass and the A259, with the local Vinnetrow Road making the fifth arm.
The following junction arrangements were tested for performance against the 2034 design year traffic: • At-grade signalised roundabout (current geometry) • Full movement signalised cross-roads (Vinnetrow Road diverted onto A259) • Grade-separated layout with mainline elevated (Vinnetrow Road diverted onto A259)
5.2.5.1. At-grade Signalised Roundabout
The modelling determined that the Bognor junction would cater for 2014 traffic if signalised, however would not have enough capacity for 2034 traffic. This arrangement was found to fail at some stage between 2014 and 2029. 5.2.5.2. Signalised Full-Movement Crossroads (Vinnetrow Road diverted) A full-movement signalised cross-road junction has been modelled, with Vinnetrow Road diverted onto the A259, and was found to be over capacity before 2029.
Page 46 of 132 Project Support Framework (Consultancy) 2011 – 2016 A27 Chichester Bypass Technical Appraisal Report
Figure 5.10: Proposed Signalised Full-Movement Crossroads
5.2.5.3. Grade Separated Junction
A grade-separated, non-signalised junction was modelled for 2034 traffic volumes. This layout increases capacity by removing the mainline traffic from the junction and allowing it to flow un-hindered. This in-turn allows the side-road traffic to negotiate the junction without having to compete with the high volume main-line flow. This model has assumed the relocation of Vinnetrow Road, with the transfer of traffic onto the A259.
Our preliminary modelling shows that the grade-separated layout will cater for the 2034 design year traffic.
Figure 5.11: Proposed Grade Separated Junction
Page 47 of 132 Project Support Framework (Consultancy) 2011 – 2016 A27 Chichester Bypass Technical Appraisal Report
5.2.6 Oving Junction
Oving junction is currently a signalised crossroads between the existing Chichester Bypass and Oving Road which permits all movements.
The following junction arrangements were tested for performance against the 2034 design year traffic: • Existing signalised full-movement crossroads • Cross-roads with banned right turns • Developer design with banned rights turns and buses only straight ahead.
5.2.6.1. Existing Signalised Full-Movement Crossroads
Oving junction was modelled in its existing configuration for both 2014 and 2034 traffic. It was found to work for 2014 demand but fails before 2029.
Figure 5.12: Existing Oving Junction
5.2.6.2. Signalised Crossroads with Banned Right Turns
A variation on the existing crossroad configuration has been modelled, with banned right turns. This arrangement is shown below and has been found to work up to the year 2034.
Page 48 of 132 Project Support Framework (Consultancy) 2011 – 2016 A27 Chichester Bypass Technical Appraisal Report
Figure 5.13: Proposed Signalised Crossroads with Banned Right Turns
5.2.6.3. Crossroads as Section 278 Developer Design
This arrangement has already been proposed as part of Section 278 works to facilitate a housing development and includes banned right turns and buses only out of Oving Road East. The arrangement has been shown below and the modelling has shown it will cater for traffic up to the year 2034.
Figure 5.14: Crossroads as Section 278 Developer Design
5.2.7 Portfield Junction
Portfield Junction is currently a four arm at-grade roundabout at the junction between the existing Chichester Bypass, the A285 and the old Chichester By-pass.
Page 49 of 132 Project Support Framework (Consultancy) 2011 – 2016 A27 Chichester Bypass Technical Appraisal Report
The following junction arrangements were tested for performance against the 2034 design traffic: • Existing Layout • Additional lanes on the westbound approach • Additional lane on circulatory carriageway (road marking amendment only)
Grade separation at this location is not possible as the radius of the curve of the existing Chichester Bypass through the junction is too small to fit a 120kph design to, even with relaxations. 5.2.7.1. Existing Layout
Portfield Junction was modelled in its existing configuration for both 2014 and 2034 traffic. It was found to work for 2014 demand but fails with 2034 demand levels due to extensive queuing on the A27 northbound arm. The existing arrangement works up to 2029 but fails before 2034.
Figure 5.15: Existing Portfield Junction
5.2.7.2. Additional Lanes on Westbound Approach
This layout provides an additional two lanes on the westbound approach to cater for the large left-turn movement. This has been modelled and found to fail before 2029.
Page 50 of 132 Project Support Framework (Consultancy) 2011 – 2016 A27 Chichester Bypass Technical Appraisal Report
Figure 5.16: Proposed Additional Lanes on Westbound Approach
5.2.7.3. Additional Lanes on Circulatory Carriageway
It is proposed to add one additional lane on the circulatory carriageway between the existing Chichester Bypass southern arm and the A27 eastern arm. This could be achieved by simply amending the road markings and will facilitate the right turning movement between the two carriageways.
This layout has been modelled and found to work for 2034 traffic levels.
Figure 5.17: Additional Lanes on Circulatory Carriageway
Page 51 of 132 Project Support Framework (Consultancy) 2011 – 2016 A27 Chichester Bypass Technical Appraisal Report
5.2.8 Stockbridge Link Road
To mitigate the effects of proposed turning restrictions at Stockbridge and Whyke junctions, a link road has been proposed to run from Fishbourne Junction down to join with the A286 just south of Stockbridge with a roundabout and then with a possible extension on to the B2145, see Figure 5.18. This is proposed as a single carriageway and relies on an upgrade of Fishbourne Junction to a grade-separated junction.
Figure 5.18: Stockbridge Link Road and Extension
5.2.9 Online Option Descriptions The individual junction assessment results have been combined to give overall route summaries for the various online options, namely options 11; 13, 15, 19, W, X, 1, 2 and the combined routes F, G, H, & J.
Option 11 included a grade separated roundabout at Fishbourne junction, signalised full movement crossroads at Stockbridge, Whyke and Bognor junction. No changes were considered at Oving and Portfield.
Option 13 included a grade separated roundabout at Fishbourne junction. Stockbridge, Whyke and Oving are signalised with right turns banned and straight across movements from radial routes restricted to buses only. Bognor junction is a grade separated roundabout and no change is proposed at Portfield.
Option 15 included a grade separated roundabout at Fishbourne junction with Stockbridge Link Road as an additional arm joining at the southern end between A27E and A259S. All other junctions are the same as in option 13.
Option 19 included a grade separated roundabout at Fishbourne junction, a full movement signalised crossroad at Stockbridge, signalised roundabouts at Whyke and Bognor and the existing layouts for Oving and Portfield.
Option W included a hamburger layout for Fishbourne, signalised junctions with banned right turns for Stockbridge, Whyke and Oving, apart from Oving Road East, where the ahead movement is banned instead. Bognor and Portfield are increased size roundabouts with Bognor being signalised.
Page 52 of 132 Project Support Framework (Consultancy) 2011 – 2016 A27 Chichester Bypass Technical Appraisal Report
Option X included a hamburger layout for Fishbourne, full movement crossroads at Stockbridge and Whyke, a larger signalised roundabout at Bognor and a signalised junction with banned right turns at Oving. At Oving the Oving Road East approach is banned for all traffic except buses. Portfield has a widened westbound approach.
Option 1 includes grade separation at Fishbourne, signalised cross-roads with banned right turns at Stockbridge and Whyke, grade separation at Bognor Road, Oving Cross Roads (as per developer plans) and Portfield is a peak time signalised roundabout.
Option 2 includes grade separation at Fishbourne with an additional arm for Stockbridge Link Road, a flyover (no junction) at Stockbridge and Whyke, grade separation at Bognor Road, Oving cross roads (as per developer plans), Portfield is a peak time signalised roundabout.
For layouts detailing the online options refer to the Options Appraisal Report, 343538-09- 010-RE-003.
Page 53 of 132 Project Support Framework (Consultancy) 2011 – 2016 A27 Chichester Bypass Technical Appraisal Report
5.3 Offline Option Development
5.3.1 Design Strategy
At this stage all offline routes have been designed to Dual 2 All Purpose (D2AP) specifications, with a 120kph design speed. If after completion of modelling the predicted traffic levels indicate a single carriageway would suffice, then consideration will be given to altering the design accordingly. Designing the road to a D2AP standard maintains constancy in standards with the adjacent sections of the A27. In addition, the Dual 2 All Purpose design criteria is more stringent so the design would be to a higher standard and easier to convert to Single Carriageway with a more relaxed horizontal and vertical alignment if required. The design speed of 120kph has been chosen as this is typical for a rural dual carriageway configuration and in keeping with the existing A27 in this area.
5.3.2 Offline Route Selection and Refinement
Corridor selection
The initial route options were designed based on the visible corridors in the land, and then drawn using minimal relaxations from standards to produce the Options 1, 3, 5, 7, 8, 10 and 11 shown in Appendix C – Original Offline Route Options.
An option that passed to the South West of Chichester, through the Chichester Harbour, was not considered as it would impact on the RAMSAR, SSSI and AONB that cover this area. We then refined these, applying relaxations to the curve radii to reduce land take, avoid environmental constraints and minimise disruption to existing properties to produce Options 2, 4, 6, 9 and 12.
From this list we then discarded the following options:
• Option 1 – Considerably lengthy route that cuts through a significant area of ancient woodland to the West. To the East the route cuts through several properties and a business park in Strettington. Option 2 improves on both of these, although does impact a property in Westerton. • Option 3 – Requires the demolition of a number of homes in West Broyle and a larger area of woodland than Option 4. To the East the route cuts through several properties and a business park in Strettington, avoided by Option 4, although this does impact a property in Westerton. • Option 5 – Cuts through the middle of a large body of water just prior to tying in to the A27 at the Eastern end of the route, Option 6 reduces this. • Option 7 – Would require the demolition of numerous properties in Tangmere and a tighter radius to re-join the existing A27 corridor further west would conflict with the location of the current junction with the A285. • Option 8 – Significant earthworks required to cross East Trout Lake, Runcton Lake, and Vinnetrow Lake. Also would significantly impact the Chichester Lakeside Holiday Park and a number of properties located along School Lane to the south. • Option 9 – Similar issues to Option 3 to the western end of the route, but the improved alignment to the route was incorporated into Options 2 and 4.
Page 54 of 132 Project Support Framework (Consultancy) 2011 – 2016 A27 Chichester Bypass Technical Appraisal Report
• Option 10 – Proposed to alleviate traffic round Whyke and enable construction of a dumbbell junction. Removed due to the minimal advantages in improving this junction when compared to the construction cost and buildability given the proximity of the lakes.
The remaining options are Options 2, 4, 6, 11 and 12.
These options were then further refined as follows;
• Option 2 – Now forms the western part of Routes A & B, refined to reduce the severance relating to Hunters Race and the B2178 at West Broyle. • Option 4 – Now forms the western part of Routes C & D, refined to avoid Sewage Treatment Plant located off Fordwater Road to the west of Goodwood Airfield. • Option 6 – Now forms Route F, refined to reduce impact on local properties, although consequentially intrudes into the proposed Shopwhyke Strategic Development Area • Option 11 – Stockbridge Link Road, part of the on-line improvements to alleviate difficulties with restricting turning movements at Stockbridge junction • Option 12 – Now forms Route E, refined to tie in at the western end further east to reduce the potential impact to the Roman Villa scheduled monument in Fishbourne. Also refined to no longer merge with the main carriageway between Whyke and Bognor Road roundabouts, instead running adjacent to reduce the severance issues the previous alignment caused.
In addition to the above, a new corridor has been identified to the east of Chichester that bypasses the Tangmere/Boxgrove junction instead utilising the corridor of land between Boxgrove and Halnaker. This has the double advantage of avoiding a Noise Important Area between Tangmere and Boxgrove, reducing the severance between these two villages, and increasing the distance until the next at-grade junction until the roundabout at Fontwell, 2.7 miles away. This new corridor now forms the eastern part of Routes A & C, with Option 4 forming the western part of Routes B & D.
A Route G has also been identified, which ties in to the existing A27 Chichester Bypass between the Whyke and Bognor Road roundabouts, then heads East, to the South of Shopwhyke Park then North alongside the proposed Tangmere Strategic Development Area and joining in to the existing dumbbell junction between the A27 and the A286, which will need upgrading to take the increased traffic loads. This route is similar to Route F, although has the advantages of not encroaching on any proposed development areas and avoiding any large bodies of water, although the key disadvantage is that the junction with the A27 is effectively at-grade and through traffic heading West along the A27 will have to intentionally deviate from the mainline to continue on the trunk road, and so the journey will be perceived as disjointed to users.
Route H has been identified as an alternative path to Routes E & F, which cut up through the Shopwhyke Strategic Development Area, and instead runs further east, along the boundary of Westbourne House School. A Route J has also been identified that joins to the same point of the A27 Routes F, G and H, but runs further east, to the south of
Page 55 of 132 Project Support Framework (Consultancy) 2011 – 2016 A27 Chichester Bypass Technical Appraisal Report
Tangmere with a tie in similar to Routes A & C at Crockerhill. These routes can be seen in Appendix D – Refined and Hybrid Offline Route Options.
5.3.3 Offline Route Descriptions
Route A
Route A is a new bypass to the north of Chichester, approximately 11.8km in length. The proposed bypass will tie-in to the existing A27 at Ratham Lane and Clay Lane to the West, and at Crocker Hill (B2233 Nyton Road) to the East.
Route Description
Route A ties in to the existing A27 to the west of the Clay Lane bridge. The alignment passes to the west of West Broyle adjacent to the existing Hunter’s Race. The route also follows the alignment of New Road north of Goodwood Aerodrome along the southern boundary of the South Downs National Park.
The alignment continues along New Road and then passes to the north of Boxgrove to tie- in to the A27 west of Crockerhill.
Summary of Benefits
• Uninterrupted route for through traffic all the way to Fontwell by avoiding at-grade junction at Tangemere, creating a continuous grade-separated dual carriageway between Ringwood on the A31 to the West and Fontwell on the A27 to the East (62 miles) • Addresses area of priority noise concern between Tangmere and Boxgrove • Re-uses existing road corridors where possible • Avoids major disruption to existing settlements, with the exception of Strettington • Majority of route constructed offline so should minimise disruption to local traffic during works • Could support better access to Goodwood sites depending on junction strategy solutions.
Summary of Difficulties
• Route skirts the edge of the South Downs National Park, would need approval for any ingress • Whilst visual intrusion is minimised by keeping the new bypass at-grade, there is likely to be significant objection to any visual intrusion, and a number of local roads will need elevating over the bypass, posing further visual intrusion. • Severs the small village/hamlet of Strettington, involving the likely demolition of several listed buildings • Number of structures required to reduce local route severance • Passes close to West Broyle, East Lavant and Boxgrove, may generate a strong reaction from these communities.
Page 56 of 132 Project Support Framework (Consultancy) 2011 – 2016 A27 Chichester Bypass Technical Appraisal Report
• Some improvements to existing on-line bypass may still be required so that the traffic demand at a local level is met for the design year. • Route passes nearby to West Broyle, East Lavant and the north of Chichester which may generate strong resistance. • One of the lengthiest routes.
Figure 5.19 Route A Location Plan
Route B
Route B is a new bypass to the north of Chichester, approximately 9.4km in length. The proposed bypass will tie-in to the existing A27 at Ratham Lane and Clay Lane to the West, and at Tangmere Rd to the East.
Route Description
Route B ties in to the existing A27 to the west of the Clay Lane bridge. The alignment passes to the west of West Broyle adjacent to the existing Hunter’s Race. The route also follows the alignment of New Road north of Goodwood Aerodrome along the southern boundary of the South Downs National Park.
The alignment passes through the edge of Westerton and crosses the A285 to tie in to the existing A27 east of the current junction with the A285 and A27, before the Tangmere roundabout.
Page 57 of 132 Project Support Framework (Consultancy) 2011 – 2016 A27 Chichester Bypass Technical Appraisal Report
Page 58 of 132 Project Support Framework (Consultancy) 2011 – 2016 A27 Chichester Bypass Technical Appraisal Report
Summary of Benefits
• Avoids major disruption to existing settlements. • Re-uses existing road corridors where possible • Large majority of works constructed off-line, so should minimise disruption to local traffic during works. • Could support better access to Goodwood sites depending on junction strategy solutions. • A possibility exists to create a continuous grade-separated dual carriageway between Ringwood on the A31 to the West and Fontwell on the A27 to the East (62 miles), if the at-grade Tangmere junction is addressed. • Reduced length compared to routes A and C.
Summary of Difficulties
• Route skirts the edge of the South Downs National Park, would need approval for any ingress • Route passes nearby to several listed properties, adversely effecting them. • Number of structures required to reduce local severance. • New bypass will be interrupted by existing at-grade roundabout between Boxgrove and Tangmere, unless addressed as separated scheme. • Proposed route passes through some land already earmarked for development. • Route passes nearby to West Broyle, East Lavant and the north of Chichester which may generate strong resistance. • Whilst visual intrusion is minimised by keeping the new bypass at-grade, there is likely to be significant objection to any visual intrusion, and a number of local roads will need elevating over the bypass, posing further visual intrusion. • Some improvements to existing on-line bypass may still be required so that the traffic demand at a local level is met for the design year.
Page 59 of 132 Project Support Framework (Consultancy) 2011 – 2016 A27 Chichester Bypass Technical Appraisal Report
Figure 5.20 Route B Location Plan
Route C
Route C is a new bypass to the north of Chichester, approximately 11.3km in length. The proposed bypass will tie-in to the existing A27 approximately 30m east of the Clay Lane overbridge at the western end, loop around Chichester to the north and then back into the existing A27 adjacent to Crocker Hill (B2233 Nyton Road) to the East.
Route Description
Route C ties in to the existing A27 east of the Clay Lane bridge. The alignment passes to the east of West Broyle, through the West of Chichester Strategic Development Area. The route passes to the north of Goodwood Aerodrome along the existing corridor of New Road, along the southern boundary of the South Downs National Park.
The alignment continues along New Road and then passes to the north of Boxgrove to tie- in to the A27 west of Crockerhill.
Summary of Benefits
• Uninterrupted route for through traffic all the way to Fontwell by avoiding at-grade junction at Tangemere, creating a continuous grade-separated dual carriageway between Ringwood on the A31 to the West and Fontwell on the A27 to the East (62 miles)
Page 60 of 132 Project Support Framework (Consultancy) 2011 – 2016 A27 Chichester Bypass Technical Appraisal Report
• Addresses area of priority noise concern between Tangmere and Boxgrove • Re-uses existing road corridors where possible • Avoids major disruption to existing settlements • Large majority of route constructed offline so should minimise disruption to local traffic during works • Could support better access to Goodwood sites depending on junction strategy solutions.
Summary of Difficulties
• Route skirts the edge of the South Downs National Park, would need approval for any ingress • Severs the small village/hamlet of Strettington, involving the likely demolition of several listed buildings • Number of structures required to reduce local route severance • Whilst visual intrusion is minimised by keeping the new bypass at-grade, there is likely to be significant objection to any visual intrusion, and a number of local roads will need elevating over the bypass, posing further visual intrusion. • Passes close to West Broyle, East Lavant and Boxgrove, may generate a strong reaction from these communities. • Some improvements to existing on-line bypass may still be required so that the traffic demand at a local level is met for the design year. • One of the lengthiest routes.
Page 61 of 132 Project Support Framework (Consultancy) 2011 – 2016 A27 Chichester Bypass Technical Appraisal Report
Figure 5.21 Route C Location Plan
Route D
Route D is a new bypass to the north of Chichester, approximately 8.9km in length. The proposed bypass will tie-in to the existing A27 approximately 30m west of the Clay Lane overbridge at the western end, loop around Chichester to the north and then back into the existing A27 adjacent to Tangmere and Boxgrove.
Route Description
Route D ties in to the existing A27 east of the Clay Lane bridge. The alignment passes to the east of West Broyle, through the West of Chichester Strategic Development Area. The route passes to the north of Goodwood Aerodrome along the existing corridor of New Road, along the southern boundary of the South Downs National Park.
The alignment passes through the edge of Westerton and crosses the A285 to tie in to the existing A27 east of the current junction with the A285 and A27, before the Tangmere roundabout.
Summary of Benefits
• Avoids major disruption to existing settlements. • Re-uses existing road corridors where possible
Page 62 of 132 Project Support Framework (Consultancy) 2011 – 2016 A27 Chichester Bypass Technical Appraisal Report
• Large majority of works constructed off-line, so should minimise disruption to local traffic during works. • Could support better access to Goodwood sites depending on junction strategy solutions. • A possibility exists to create a continuous grade-separated dual carriageway between Ringwood on the A31 to the West and Fontwell on the A27 to the East (62 miles), if the at-grade Tangmere junction is addressed. • Reduced length compared to routes A and C.
Summary of Difficulties
• Route skirts the edge of the South Downs National Park, would need approval for any ingress • Route passes nearby to several listed properties, adversely affecting them. • Number of structures required to reduce local severance. • New bypass will be interrupted by existing at-grade roundabout between Boxgrove and Tangmere. • Whilst visual intrusion is minimised by keeping the new bypass at-grade, there is likely to be significant objection to any visual intrusion, and a number of local roads will need elevating over the bypass, posing further visual intrusion. • Proposed route passes through some land already earmarked for development. • Route passes nearby to West Broyle, East Lavant and the north of Chichester which may generate strong resistance. • Route likely to have significant visual impact on landscape. • Some improvements to existing on-line bypass may still be required so that the traffic demand at a local level is met for the design year.
Page 63 of 132 Project Support Framework (Consultancy) 2011 – 2016 A27 Chichester Bypass Technical Appraisal Report
Figure 5.22 Route D Location Plan
Route E
Route E is a new bypass to the south and east of Chichester and is approximately 8.9km in length. The proposed alignment runs adjacent to the existing Chichester Bypass on the bend between Whyke and Bognor Roundabouts, and re-joins the existing A27 1km west of the junction with the A285.
Route Description
Route E ties in to the existing A27 to the northwest of Fishbourne Roundabout. It travels round the south of Stockbridge and passes over a number of lakes to the north of the Chichester Lakeside Holiday Park, adjacent to the existing Chichester Bypass. The alignment crosses the Railway Line adjacent to Bognor Road junction, passes through the Stockbridge Strategic Development Area and ties in to the existing A27 to the west of Dairy Lane, east of the A285 junction.
Summary of Benefits
• Reduced severance minimising the effects on local traffic patterns. • Limited demolition of existing properties • Avoids built-up areas reducing noise and visual impacts on existing communities.
Summary of Difficulties
Page 64 of 132 Project Support Framework (Consultancy) 2011 – 2016 A27 Chichester Bypass Technical Appraisal Report
• Extensive earthwork solutions required to carry route over the lakes. It should also be noted at this stage the depth of the lakes is unknown. An earthwork solution will only be suitable for a maximum depth of approximately 5m, and this is the current assumption. If it transpires the lakes are deeper than envisaged, a structure may be required further increasing costs. • Loss of flood storage if lakes are used for flood storage. Lost volume will need to be made up elsewhere. • Passes close to Chichester Lakeside Holiday Park. • Complex junction arrangement at Fishbourne and no junction at Bognor Road due to space/alignment constraints. • Severing the existing A27 to the east will likely create heavy traffic on adjacent local roads (Stane Street/Roman Road), not severing the road would require a complex junction due to the proximity of the A285 junction. • Some improvements to existing on-line bypass may still be required so that the traffic demand at a local level is met for the design year.
Figure 5.23 Route E Location Plan
Page 65 of 132 Project Support Framework (Consultancy) 2011 – 2016 A27 Chichester Bypass Technical Appraisal Report
5.3.4 Hybrid Route Descriptions
Route F
Route F comprises of online improvements from Fishbourne to Bognor Road junctions and then a new bypass to the south and east of Chichester, tying in just prior to the existing dumbbell. The proposed new alignment is 4.4km in length.
Route Description
The offline element of Route F ties in to the existing Chichester Bypass to the east of Whyke Roundabout and passes close to the north of Chichester Lakeside Holiday Park. It continues northeast until it crosses the Railway Line adjacent to Bognor Road junction, passes through the Stockbridge Strategic Development Area and ties in to the existing A27 to the west of Dairy Lane, east of the A285 junction.
Summary of Benefits
• More limited road crossings reduces risk of severance • Limited demolition of existing properties • Avoids built-up areas reducing noise and visual impacts on existing communities. • Combining online and offline improvements reduces the length of new construction.
Summary of Difficulties
• Extensive earthwork solutions required to carry route over the lakes. It should also be noted at this stage the depth of the lakes is unknown. An earthwork solution will only be suitable for a maximum depth of approximately 5m, and this is the current assumption. If it transpires the lakes are deeper than envisaged, a structure may be required further increasing costs. • Loss of flood storage if lakes are used for flood storage. Lost volume will need to be made up elsewhere. • Passes close to Chichester Lakeside Holiday Park. • Improvements to online elements likely to cause significant traffic disruption.
Page 66 of 132 Project Support Framework (Consultancy) 2011 – 2016 A27 Chichester Bypass Technical Appraisal Report
Figure 5.24 Route F Location Plan
Route G
Route G comprises of online improvements from Fishbourne to Bognor Road junctions and then a new bypass to the south and east of Chichester. The proposed offline route is approximately 4.2km in length.
Route Description
The offline element of Route G ties in to the existing Chichester Bypass to the east of Whyke Roundabout and passes close to the north of Chichester Lakeside Holiday Park. It continues northeast until it crosses the Railway Line adjacent to Bognor Road junction, passes to the north of several lakes ties in to the existing A27 at the junction with the A285.
Summary of Benefits
• Provides similar benefits to route F. However, route G avoids crossing several lakes leading to savings on extensive embankments. • Requires limited grade separation of local roads • Avoids built-up areas reducing noise and visual impacts on existing communities.
Summary of Difficulties
Page 67 of 132 Project Support Framework (Consultancy) 2011 – 2016 A27 Chichester Bypass Technical Appraisal Report
• Improvements to online elements likely to cause significant traffic disruption. • The proposed alignment does not provide a continuous bypass to the existing A27 as it requires traffic to use the dumbbell junction at Temple Bar. This junction may require significant upgrades to meet the increased demand level. • The dumbbell junction mentioned above has been mooted to be part of a proposed housing development.
Figure 5.25 Route G Location Plan
Route H
Route H comprises of online improvements from Fishbourne to Bognor junctions and then a new bypass to the south and east of Chichester. The proposed alignment is approximately 4.5km long and would require 4 grade separated crossings.
Route Description
The offline element of Route H ties in to the existing Chichester Bypass to the east of Whyke Roundabout and passes close to the north of Chichester Lakeside Holiday Park. It continues northeast until it crosses the Railway Line adjacent to Bognor Road junction, passes to the east of the Westbourne House School and ties in to the existing A27 to the east of the A285 junction.
Summary of Benefits
Page 68 of 132 Project Support Framework (Consultancy) 2011 – 2016 A27 Chichester Bypass Technical Appraisal Report
• Provides similar benefits to route G. However, route H avoids crossing the Shopwhyke Strategic Development Area. • Requires limited grade separation of local roads • Avoids built-up areas reducing noise and visual impacts on existing communities.
Summary of Difficulties
• Improvements to online elements likely to cause significant traffic disruption. • The proposed route enters into the land owned by the Westbourne House School and will require realignment of the Chichester Flood Relief Channel at this location to minimise the number of crossings. • The route crosses through a number of large bodies of water
Figure 5.26 Route H Location Plan
Route J
Route J comprises of online improvements from Fishbourne to Bognor junctions and then a new bypass to the south and east of Chichester. The proposed offline route is approximately 6.3km in length and would require seven grade separated crossings.
Route Description
Page 69 of 132 Project Support Framework (Consultancy) 2011 – 2016 A27 Chichester Bypass Technical Appraisal Report
The offline element of Route J ties in to the existing Chichester Bypass to the east of Whyke Roundabout and passes close to the north of Chichester Lakeside Holiday Park. It continues northeast until it crosses the Railway Line adjacent to Bognor Road junction, passes to the north of several lakes, north of Oving, South of Tangmere and ties in to the existing A27 at Crockerhill.
Summary of Benefits
• This route provides a bypass of Tangmere (and the at-grade junction there). • Requires limited grade separation of local road. • Apart from the initial departure from the existing A27 to the West it avoids bodies of water.
Summary of Difficulties
• Improvements to online elements likely to cause significant traffic disruption. • The route crosses through the Tangmere Strategic Development Area and may require the demolition of some buildings at the Tangmere Airfield Nursery • The route passes very close to a number of properties in Tangmere and would potentially require their demolition as well as a number of properties in East Hampnett.
Figure 5.27 Route J Location Plan
Page 70 of 132 Project Support Framework (Consultancy) 2011 – 2016 A27 Chichester Bypass Technical Appraisal Report
5.4 Other Options
A number of other options have been considered at a very high level, and are reviewed in more detail in the Options Appraisal Report, 343538-09-010-RE-003. A summary of these options is below.
5.4.1 Tunnel
Due to the sensitive nature of the surrounding land the feasibility of a tunnelled solution was investigated. Whilst this offered clear benefits in terms of reduced visual and noise intrusion there were significant disadvantages to this method. The high water table in the area means that the tunnelling could be extremely complex or cost prohibitive, potentially requiring constant pumping required during operation. In addition to these tunnels are typically very expensive, and encountering difficult ground conditions can rapidly increase the cost and delay completion. For these reasons, a tunnelled solution has not been considered further.
5.4.2 Collector Distributor Lane
Another option considered was the use of collector distributer lanes, constructed adjacent to the existing Chichester Bypass and used to reduce conflicts between strategic and local traffic. This solution would potentially have lowered environmental impacts and be lower cost compared to a new bypass. This solution however faces problems with the constraints around the existing route, with a large number of properties adjacent to the existing bypass, and the link between Whyke and Bognor Road being flanked on either side by a series of lakes. Additionally it is likely to worsen the noise and air quality along the route, and may not cater for 2034 traffic, still relying on the existing closely spaced junctions. For these reasons, a collector distributer solution has not been considered further.
5.4.3 Viaduct over the existing Chichester Bypass
During a key stakeholder engagement meeting the possibility of constructing a viaduct above the existing Chichester Bypass was suggested. This would elevate the through traffic above the existing junctions, permitting the existing Chichester Bypass to be used for local traffic as a ring road. Whilst this has the key benefit of effectively grade separating all junctions, it comes with significant construction costs, complex construction of one carriageway over another, and significant noise and visual intrusion problems in a key area. For these reasons, a viaduct solution has not been considered further.
5.4.4 Public Transport Option
A review of the rail, bus and park and ride situations was undertaken as part of the scheme. It concluded that for rail any improvement would be prohibitively expensive, the funding for which would likely not be approved, and that the existing line is already running close to capacity. Reviewing the bus options concluded that some increase to service frequency on the costal route could be made that would save some car journeys. The investigation into Park and Ride revealed that it does offer some opportunity, accompanied
Page 71 of 132 Project Support Framework (Consultancy) 2011 – 2016 A27 Chichester Bypass Technical Appraisal Report by a rise in city-centre car park prices, to reduce demand on the road network. This would potentially be costly to establish, with an estimated £5m initially, with running costs of £500,000 per year. Whilst the Chichester District Council does recognise that Park and Ride may be required to manage car use within the city, it does not currently have any plans to implement such a solution. For these reasons, public transport options have not been considered further.
5.5 Environmental Status
5.5.1 Introduction
The local area in the immediate vicinity of the proposed scheme is of high environmental value, due to its location on the River Lavant, just south of the South Downs National Park (SNDP), on the south coast.
Chichester Harbour to the southwest of the City is an important area in terms of landscape, ecology and heritage; it is internationally designated as a Special Area of Conservation (SAC), Special Protection Area (SPA), and Ramsar Site, and nationally designated as a Site of Special Scientific Interest (SSSI) and Area of Outstanding Natural Beauty (AONB). The view of Chichester Cathedral from the Harbour area is considered to be historic and important. Small pockets of Biodiversity Action Plan (BAP) Priority Habitats exist across all of the proposed online and offline options, with larger pockets comprising largely Coastal and Floodplain Grazing Marsh and Mudflat to the south west, and Woodpasture and Parkland, Deciduous Woodland and Ancient Woodland around the western and northern outskirts of the City.
Historically, Chichester’s location made it an ideal place for settlement, with many ancient route ways converging here. The oldest section lies within the Medieval walls of the City, which are built on Roman foundations. As such, a plethora of Scheduled Ancient Monuments (SAMs), Listed Buildings and Conservation Areas surround the City, including Fishbourne Roman Palace, which lies approximately 350m from the route of the existing A27 bypass.
5.5.2 Proposed Route Options
Online Options
The eight proposed online options, located to the south of the city centre, include upgrades and improvements to the A27 Chichester Bypass (Options 1, 2, 11, 13, 15, 19, W and X), in addition to the construction of a new Stockbridge Link Road (included as part of Options 2 and 15), and the construction of a Whyke/Bognor link road (included as part of Option 2).
A summary of the environmental constraints for the proposed online options is provided in Appendix A – Environmental Constraints Plan. Details of the potential environmental effects of the online options are given below.
Page 72 of 132 Project Support Framework (Consultancy) 2011 – 2016 A27 Chichester Bypass Technical Appraisal Report
Offline Options
The five proposed offline options include a selection of new routes to the north of Chichester (Routes A-D) as well as an option to the south of Chichester (Route E).
Hybrid Options
In addition to the above there are four hybrid options, consisting of online improvements at the first three junctions, the reconstruction of the Bognor Road junction, and a new stretch of offline bypass that ties into the existing Chichester Bypass on the Whyke to Bognor Road link (Routes F-J).
A summary of the environmental constraints for the proposed offline options can be seen in Appendix A – Environmental Constraints Plan; a description of the potential environmental effects of the offline options is given below.
For full details of the environmental baseline for all route options, reference should be made to the Environmental Scoping Assessments that have been produced for the Online and Offline Options (Mott MacDonald, 2015).
5.5.3 Environmental Status
Noise
The existing noise environment in the study area is dominated by that of traffic on the bypass route and from radial routes linked to the bypass junctions. Five Noise Action Planning Important Areas exist within 500m of the proposed online options; these are located at Stockbridge roundabout, east and west of Whyke roundabout, and between the Bognor and Portfield roundabouts.
Noise sensitive receptors within 500m of the proposed online options include approximately 1,550 residential properties, 13 farms, four schools and more than 300 commercial properties. Existing outdoor noise levels for the noise receptors located immediately adjacent to the A27 are considered to be in the range of 69-78dB. There are no other major noise sources in the study area.
There is a Noise Action Planning Important Area designated along the existing A27 at Tangmere. In addition, a Noise Important Area is designated along the A27 to the east of Tangmere.
Local Air Quality
Chichester District Council has designated one Air Quality Management Area (AQMA) at Stockbridge Junction, for exceedences of the annual mean air quality objective, through which all eight of the online options would run. Associated with this AQMA is a continuous NO2 monitoring station, located to the east of Stockbridge Junction.
Page 73 of 132 Project Support Framework (Consultancy) 2011 – 2016 A27 Chichester Bypass Technical Appraisal Report
Greenhouse Gases
No baseline environmental information currently exists for greenhouse gases.
Landscape and Townscape
The study areas for the proposed online options lie within National Character Area (NCA) 126 South Coast Plain (NE525), characterised by a flat, coastal landscape with an intricately indented shoreline lying between the dip slope of the South Downs and South Hampshire Lowlands, and the waters of the English Channel, Solent and part of Southampton Water (NE, 2014). Chichester Harbour AONB lies within the South Coast Plain NCA, and is located approximately 450m from the western extent of the proposed online options.
The immediate landscape of the bypass is characterised by a number of roundabouts and junctions, as well as general highways infrastructure of signage, traffic lights and pedestrian overbridges with the highway alternating between two and three lanes of traffic. The existing bypass route is bordered by a variety of land uses with residential and industrial areas mainly to the north within Chichester and fields and lakes to the south. In many locations there is mature vegetation along the existing A27 comprising narrow linear tree belts or shrub planting.
In terms of townscape, Chichester lies at the centre of an area called the 'South Coast Plain' in Countryside Character Volume 7 – South East and London. The character of the study area for the proposed online options is that of an urban fringe in a flat landscape. On the southern, south-eastern and south-western fringe of Chichester, residential and light industrial development has expanded to meet the boundary formed by the bypass. Except for Chichester Harbour, Fishbourne village and the suburb of Stockbridge, the remaining landscape beyond the A27 to the south comprises flat farmland with large and medium sized fields enclosed by hedges.
The study areas for the proposed route Offline Options sit within National Character Area (NCA) 125 South Downs (NE432), and would skirt the edge of the South Downs National Park. The South Downs NCA is an extremely diverse and complex landscape with considerable local variation representing physical, historical and economic influences; much of it has been formed and maintained by human activity, in particular in agriculture and forestry.
Heritage and Historic Resources
The study area for the proposed online options is covered by the Chichester Historic Environment Records (HER). There are approximately 11 Grade I Listed Buildings and 280 Grade II Listed Buildings within 1km of the online route options.
Fishbourne Roman Palace Scheduled Ancient Monument (SAM) lies 300m from the western extent of the proposed online options, with Fishbourne Roman Palace Registered Park and Garden located just beyond. A further 4 SAMs lie within 1km of the proposed
Page 74 of 132 Project Support Framework (Consultancy) 2011 – 2016 A27 Chichester Bypass Technical Appraisal Report options. Fishbourne Conservation Area also lies within approximately 300m of these proposed options, and Chichester Conservation Area is located approximately 150m north.
The Chichester Dykes and Devils Dyke SAMs form a line from Mid Lavant to Goodwood Park, and Boxgrove Priory SAM lies within 350m of northern offline route options. Boxgrove Conservation Area also lies within 200m of these routes, to the north-east of Chichester.
All options lie within the vicinity of the Tangmere Conservation Area, with Oving Conservation Area to the east of Chichester also identified as part of the desk study.
Biodiversity
Solent Maritime SAC, Chichester and Langstone Harbours Special Protection Area (SPA)/Ramsar, Chichester Harbour Site of Special Scientific Interest (SSSI) and Mudflat and Intertidal Substrate Foreshore Biodiversity Action Plan (BAP) priority habitats are located within 500m of the proposed Scheme. In addition, the Ebernoe Common SAC, The Mens SAC and Singleton and Cocking Tunnels SAC, which are designated for bat populations, are located within 30km of the proposed works.
Fishbourne Meadows Site of Nature Conservation Interest (SNCI), Chichester Canal SNCI and Chichester Gravel Pits and Leythorne Meadow SNCI are located within 200m of the proposed Scheme. The River Lavant flows under the A27 at Fishbourne and flows into Chichester and Langstone Harbours SPA/Ramsar, Harbour SSSI and Solent Maritime SAC. In addition, pockets of BAP priority habitat exist throughout all route options. Ancient woodland scatters the study area for the proposed northern route options, and a number of Chichester Gravel Pits and Leythorne Meadow SNCI would be intersected by the proposed route Options.
The road verges and centres of Fishbourne Junction, Stockbridge Junction, Whyke Junction, Bognor Road Junction, Oving Junction, and Portfield Junction are considered to be of low conservation value, consisting of varying occasional to frequent stretches of semi-mature trees, some limited mature trees and sections of hedgerow. However, the mature trees are considered to have a medium conservation value and ecological potential to support nesting and foraging birds, and habitats within the study area have been shown to support several protected species including water voles, badgers and bat species.
Singleton and Cocking Tunnels SAC, located approximately 6km north of the proposed Scheme, and The Mens SAC and Ebernoe Common SAC, located approximately 20km north east of the proposed Scheme, are designated due to the presence of significant populations of bats. In addition, the Solent Maritime SAC, Chichester and Langstone Harbours SPA/Ramsar, Chichester Harbour SSSI and Mudflat and Intertidal Substrate Foreshore BAP priority habitats are located approximately 1,200m from the proposed Scheme.
Water Environment
Page 75 of 132 Project Support Framework (Consultancy) 2011 – 2016 A27 Chichester Bypass Technical Appraisal Report
The South East River Basin Management Plan (RBMP) (Environment Agency, 2009) provides information on four Water Framework Directive (WFD) surface waterbodies within the study area that have the potential to be either directly or indirectly affected by the proposed online and offline options, and include the River Lavant that approaches Chichester to the north east of the city and subsequently flows under the A27 between Fishbourne and Stockbridge roundabouts, Fishbourne Stream, Chichester Canal, Pagham Harbour, and Chichester Harbour East.
There are also several lakes to the southeast of Chichester, some of which could be affected by the proposed options. These lakes are thought to be historic gravel pits, which have subsequently filled with water and are now used for fishing and other recreational activities. There are numerous other unnamed watercourses and ponds in the vicinity of the study area for the proposed options.
To the southwest of Chichester the Worthing-Portsdown Chalk groundwater body (GB40701G500700) underlies the proposed online options. There is an area of Groundwater Source Protection Zone (Zone I) located approximately 750 m to the west of Fishbourne roundabout, and the western extent of the scheme lies within a Eutrophic Nitrate Vulnerable Zone Area.
The Environment Agency’s (EA) indicative flood mapping shows that the proposed options would run through areas of Flood Zones 1, 2 and 3.
The majority of offline options would pass through areas of Groundwater Source Protection Zone (SPZ) 1, 1C, 2, and 3, located to the northwest and northeast of Chichester, and the western extent of the proposed options lies within a Eutrophic Nitrate Vulnerable Zone Area. In addition, the whole of the proposed route lies in a Groundwater NVZ. The eastern extent of the Scheme lies in a surface water NVZ area.
Physical Fitness
Numerous Public Rights of Way (PRoW) occur along the study area for the proposed online options, used by pedestrians, cyclists and equestrians.
Journey Ambience
To the north of the proposed Scheme, traveller views are dominated by residential and light industrial developments in the city of Chichester. To the south, the villages of Fishbourne and Stockbridge comprise the notable urban developments. Traveller views are otherwise largely dominated by agricultural land interspersed with water features. The views are predominantly flat, with the spire of Chichester Cathedral in the city centre as the only significant landmark.
The level of driver stress at the more congested A27 junctions of Fishbourne, Stockbridge, Whyke and Bognor is considered to be high. However, the level of driver stress at the less congested junction at Oving is considered to be moderate.
Page 76 of 132 Project Support Framework (Consultancy) 2011 – 2016 A27 Chichester Bypass Technical Appraisal Report
Within the study area for the proposed route Offline Options, traveller views would be expected to be dominated by agricultural land and pockets of wooded habitats, interspersed with farm buildings, individual dwellings, and the outskirts of the villages of Fishbourne, East Lavant, Boxgrove, and Tangmere.
Page 77 of 132 Project Support Framework (Consultancy) 2011 – 2016 A27 Chichester Bypass Technical Appraisal Report
6 Traffic Analysis 6.1 Introduction
The Chichester Area Traffic Model (CATM) has been used previously to assess a number of options to relieve congestion on the existing Chichester Bypass for Highways England, Chichester District Council and West Sussex County Council. The CATM is now out of date and non WebTAG compliant, and therefore needs updating in order to test the latest options to relieve congestion along the existing Chichester Bypass.
The Appraisal Specification Report produced by in January 2015 details the methodology proposed to update the CATM. This is summarised in section 6.3 below.
6.2 Traffic Data
As part of the CATM update, the following existing traffic data sources have been collated and reviewed: • West Sussex County Council traffic database (WSCC) • Highways England traffic information database (TRADS) • Highways England journey time database (JTDB) • Department for Transport traffic count database (DfT)
Also reviewed were existing reports from previous studies and existing traffic models with relevant traffic survey data and network information used in the update of CATM.
Based on the review of the data available and an understanding of the data required to build the updated CATM, additional traffic data collection has been undertaken. This has consisted of: • Four classified link counts • Eight classified junction turning counts • Seven moving observer journey time route surveys • Mobile phone data
The link counts, junction counts and journey time surveys were undertaken in June and November 2014. Anonymised mobile phone data was collected for the weeks of 7th and 14th July.
The link, turning counts and journey time surveys will be used in the base year model calibration and validation with the mobile phone data being used to build the base year matrices.
Full details of the traffic survey data used as part of the CATM update can be found in the January 2015 Traffic Data Collection Report.
Page 78 of 132 Project Support Framework (Consultancy) 2011 – 2016 A27 Chichester Bypass Technical Appraisal Report
6.3 Traffic Modelling Methodology
The purpose of developing the new model is to forecast the traffic impacts of options to relieve congestion along the existing Chichester Bypass.
6.3.1 Base year model
The detailed study area will be based on that used in CATM encompassing the main centres of Chichester and Bognor Regis. It will extend to the coast, the Hampshire border, the northern edge of the South Downs and include parts of Arun district to the west of Arundel and the River Arun. The model will be covering the highway mode only.
Anonymised mobile phone data will use O2 as the mobile provider and Inrix to facilitate the transfer of data. The data collected is double-anonymised with trips within the study area defined to a high level of accuracy of between 5-20 metres. The data will be extracted to determine the true origin and final destination of External-External trips passing through the study area on the main A roads. Data will only be collected from moving phones (either in-use or in passive mode).
Previously developed algorithms will be used to • determine ‘rules’ for trips which stop for a period of time, in order to be able to define trip chaining • omit slow-modes • split the remaining trips into highway and train
The mobile phone data will be cleaned and processed to trip records. Data for all phones / individuals are aggregated to obtain demand matrices at OD level by time period. Trips inferred as using the Rail with mode of travel will be excluded. The data is associated with expansion factors which are applied to scale the mobile phone sample to a full expanded dataset.
Car trips will be split into three journey purposes, namely work/commuting, employer business, and other. In addition LGV and HGV demand will be modelled as discrete classes. Highway assignments will be based on peak hour flows for the morning and evening periods (0800 to 0900 and 1700 to 1800) and average hour for inter-peak using SATURN.
Variable demand modelling will be undertaken using DIADEM at an OD level using 12 hour data with trip frequency and destination choice responses included. Macro and micro time period choice and income segmentation are not required
The highway model will be calibrated and validated against traffic count data based on highway screenlines formed ATC’s placed around Chichester, normalised to the year and month of the new base year model, based on a Tuesday to Thursday average weekday. Realism testing for the demand model will be carried out in accordance with the advice in WebTAG Unit M2 Section 6.
Page 79 of 132 Project Support Framework (Consultancy) 2011 – 2016 A27 Chichester Bypass Technical Appraisal Report
6.3.2 Traffic forecasting
Traffic forecasting will use factors constrained to TEMPRO growth to update production and attraction trip ends for each zone for each purpose/mode combination. The four largest strategic housing sites included in the Chichester District Council Local Plan are large developments close to the A27 Chichester Bypass. These will be modelled explicitly as zones in their own right using planning assumptions from the Chichester Local Plan. LGV and OGV matrices will be scaled using the national growth factors obtained from NRTF.
Traffic forecasts will be prepared for 2019, scheme opening year, 2034 and 2041 and for a core scenario, with low growth and high growth sensitivity tests run at a minimum.
Outputs from the traffic forecasts will provide inputs to the environmental and operational assessments of the scheme
Page 80 of 132 Project Support Framework (Consultancy) 2011 – 2016 A27 Chichester Bypass Technical Appraisal Report
7 Economic Assessment
The Lot 5 provider, Jacobs, will assess the majority of the economic impacts of the improvements using DfT’s WebTAG (Web-Based Transport Analysis Guidance) based upon HM Treasury (HMT) Green Book principles.
The WebTAG guidelines provide a detailed methodology for quantifying a wide range of potential impacts of a transport scheme and monetizing them wherever possible. According to the WebTAG guidelines, the potential impacts of the improvements will be categorised under three main objectives as Economy, Environment and Society. These objectives will be further subdivided into sub-objectives such as Journey Times, Journey Times Reliability, Noise, Air Quality, Greenhouse Gas Emissions, and Accidents. The proposed economic assessment of A27 improvements will assess all of the above impacts according to the guidelines and the results will be summarised in an Appraisal Summary Table (AST) as prescribed in the WebTAG guidelines.
In terms of the benefit assessment, scenarios with ‘High’ and ‘Low’ estimates will be assessed as sensitivity tests. With regards to the construction and maintenance cost, WebTAG does not require the production of Highest and Lowest Cost Scenarios as part of the economic assessment. A single ‘Best Estimate’ will be applied which will include a risk allowance based upon a quantified risk assessment including the optimism bias in accordance with HMT Green Book guidance. The estimate, the risk assessment and the optimism bias will be further refined as the scheme progresses towards the detailed design phase by when the design work will allow for the most accurate quantification of the risks and costs. At the end of each scheme stage, the net present value and benefit cost ratio (BCR) from the proposed improvement scheme will be calculated on the basis of the latest cost estimates.
Jacobs will undertake the proposed economic assessment in a customised Excel Spreadsheet based assessment tool which will incorporate all TUBA and QUADRO assessments. The strategic transport travel demand model will be used to extract daily vehicular traffic data for the economic, environment and society impact assessments. The Journey Time savings, Reliability benefits and Accident benefits will also be derived from the traffic data obtained from the strategic transport travel demand model and using the economic assessment spreadsheet incorporating TUBA and QUADRO assessments as discussed above.
Annual traffic (flows and speed) will be estimated from the daily traffic output from the model. The annual traffic estimate will be based on the annualisation factors calculated from the data analysis of the observed daily traffic on the A27 obtained from the Highways England ATC loops and other available real-time traffic data from WSCC. The same observed data will also be used to estimate the day trip factors for the non-modelled time periods.
Based on the data and requirements, Jacobs will propose a suitable methodology and discuss and finalise with Highways England to incorporate the non-modelled time periods in the impact assessment.
Page 81 of 132 Project Support Framework (Consultancy) 2011 – 2016 A27 Chichester Bypass Technical Appraisal Report
Annual flows and average speeds will be provided to the environmental team as inputs into the calculation of monetised noise benefits.
A sensitivity test will be specified in agreement with Highways England to assess the impacts on the scheme’s benefits of the assumed parameters. The results of the economic assessment will be summarized in an Appraisal Summary Table. The elements (JT reliability, Wider impact benefits) pertaining to the wider economic benefits (or cost) will be discussed and agreed with Highways England and will be incorporated in the overall economic appraisal and the Appraisal Summary Table.
7.1.1 TUBA Assumptions
The estimation of scheme costs is a crucial part of the scheme appraisal. Economic assessment considers both the actual cost of the scheme and the projected capital cost of maintenance in future years.
Base cost estimates for construction, land/ property and preparation and administration, including adjustment for risk and optimism bias will be provided by the Highways England Commercial team. Costs will be provided in the DfT's standard base year 2010.
The capital cost of maintenance is the cost of people, machinery and materials to maintain the highway network. The best available information on maintenance costs with / without the scheme for the 60 year appraisal period will be obtained from the Lot 1 supplier and Highways England.
7.1.2 Construction Delay
During the construction of the scheme, delays will be experienced by road users. These delays can be kept to a minimum through the use of effective traffic management but are unlikely to be removed all together. This results in travel time and Vehicle Operating Cost (VOC) disbenefits on the existing network that should be considered as part of the AMCB.
QUADRO is the industry-standard software and will be used to value the delays to road users using the standard economic parameters within the program.
Construction activities, traffic management arrangements and diversion routes will be coded into QUADRO, which will then be run to simulate the impact of the construction activities on travel times, VOC and accidents on the existing A27 and surrounding network.
7.1.3 Transport Economic Efficiency - Maintenance Delay
Delays will be experienced by road users during periods of maintenance in both the existing situation and the Do Something situation. In the existing situation, delays caused by maintenance will be significant due to traffic diversions on to alternative routes when the existing A27 is closed or running at reduced capacity.
Traffic flows in the Do Something situation are likely to increase as a result of more traffic using the scheme. However, it is expected that maintenance delays would be relieved due to the new scheme.
Page 82 of 132 Project Support Framework (Consultancy) 2011 – 2016 A27 Chichester Bypass Technical Appraisal Report
QUADRO is the industry-standard software and will be used to value the delays to road users using the standard economic parameters within the program.
Maintenance activities, traffic management arrangements and diversion routes will be coded into QUADRO, which will then be run to simulate the impact of the maintenance activities on traffic on the A27 and surrounding network.
7.1.4 Accidents Assumptions
COBALT is the industry standard software used to derive the accident impacts of a scheme.
COBALT uses junctions and links to represent the Do Minimum and Do Something highway networks. Accident data for the most recent five year period is entered in to the COBALT network along with existing and future annual average daily traffic flows from the traffic model.
COBALT calculates existing accident rates based upon existing records and estimates future accident numbers based upon default accident rates in the Do-Minimum and Do- Something scenario for each option. For new links in the Do-Something scenario default accident rates are used to calculate the number of accidents. COBALT then compares the predicted numbers of accidents with and without a scheme, and converts them into monetary values by multiplying the numbers of accidents by their monetised costs.
COBALT outputs the accident benefits for the scheme over the 60 year appraisal period in 2010 prices and discounted to 2010.
Page 83 of 132
Project Support Framework (Consultancy) 2011 – 2016 A27 Chichester Bypass Technical Appraisal Report
9 Maintenance assessment
As described in Section 8.2, Safety of Road Workers, Highways England has an unambiguous policy regarding its stance towards road worker safety. This section also details key features in design to assist in ensuring road worker safety.
To obtain current feedback from those maintaining the existing Chichester Bypass, the MMGJV Design Team met with representatives from the Area 4 maintenance team on 11th February 2015. During that meeting aspects of the design were identified where there is potential to facilitate maintenance of these online and offline routes.
9.1.1 Online and Offline - Flooding
There is a need to ensure any future balancing ponds do not become habitats that would prevent the pond from receiving surface runoff, whether this would require legal or physical protection is unclear.
A number of the existing V-Channels on the existing Chichester Bypass are poor at self- cleansing, filling with debris and detritus that not only inhibits drainage but also can promote vegetation growth. To alleviate this problem the design team should ensure V- channels have adequate fall to be self-cleansing.
French Drains are prone to collecting silt and if not maintained properly then become host to vegetation, which could pose a hazard to errant vehicles and adds an extra maintenance burden. The maintenance teams suggest avoiding French drains in the design if possible and to investigate an alternative method.
At a number of locations on the existing Chichester Bypass the culverts and channels outfall into ditches that should be maintained by the riparian land owner, however these are often in a state of disrepair and so inhibit free flow. Whilst this is not a problem specific to this scheme it was highlighted that Highways England should be advised to pursue landowners not fulfilling their riparian maintenance duties.
9.1.2 Offline - Maintenance Access
To ensure safe access during maintenance works there needs to be a suitable location to park a maintenance vehicle and carry out the works on foot. The existing Chichester Bypass has a few locations where maintenance laybys have been installed which have proven useful. The recommendation is that the design should consider that enough “Grasscrete” style lay-bys are proposed in safe locations where the extent of the scheme permits.
To minimise the risk from slips, trips and falls the design should consider steps and footpaths for access where required, but also to ensure they are low maintenance to minimise road worker exposure to hazards when maintaining them.
Page 99 of 132 Project Support Framework (Consultancy) 2011 – 2016 A27 Chichester Bypass Technical Appraisal Report
9.1.3 Offline - Vegetation Growth and Trees
Whilst having vegetation and trees close to the road can be beneficial from an environmental standpoint, they require more frequent maintenance to ensure they are outside the working width of the safety barrier. The specification of slow-growing trees and other vegetation would assist in reducing the maintenance requirements. In recent high winds a number of trees fell on the carriageway, which is a hazard that can be minimised by ensuring any future planting is set a suitable distance back from the carriageway edge.
9.1.4 Online and Offline - Vehicle Restraint Systems
Concrete barrier in the central reserve is typically preferred due to the minimised maintenance implications over time and after barrier strikes.
Where possible it was recommended that cross-over points be considered as part of the design to permit the closing of a carriageway in a contra-flow operation to improve road worker safety during maintenance operations, the A22 near Eastbourne was provided as a good example.
9.1.5 Offline - Signs
The maintenance team expressed a preference for the Gantry Mounted Variable Message Signs to allow them to effectively warn of conditions ahead as well as allowing easy diversions signage as due to a proliferation of VMS on the network a number of drivers now expect to see them rather than the folding diversion signs.
9.1.6 Online - Structures
The existing Stockbridge footbridge requires gritting and is unsuitable for disabled users due to the lack of landings on the approaches. This combined with the narrow width of the span, the heavy use it sees and the vehicle strike that occurred has led the maintenance team to express a preference for replacing this structure should the option be available.
The Chichester Canal Underpass is often occupied by vagrants who set up residence there, posing a security concern to pedestrians and cyclists. Additionally there are poor connections between this and local footpaths, encouraging people to make their own paths to connect to between this and the local footpath network.
9.1.7 Offline - Future Design
Any single carriageway design would need to incorporate enough safe-guarding to widen without compromising design, such as maintaining wide verges if used. There is the possibility to use a Dual Carriageway design, with Central Reserve/VRS and On/Off Slips, but only have a single lane to permit easier conversion to two lanes running later.
The addition of a suitable diversion route would be very welcome as current diversion routes are unsuitable for the type and levels of traffic present on the existing Chichester Bypass.
Page 100 of 132 Project Support Framework (Consultancy) 2011 – 2016 A27 Chichester Bypass Technical Appraisal Report
A temporary junction at Goodwood would be welcome as the events there currently cause extreme congestion on the bypass and surrounding local roads, and this would provide a more unified approach to the estate. The maintenance teams have stated they would have no problem with closing off and opening up the access as required.
They additionally suggested bunding with trees sitting at the top of the bunding, which encourages wide grass verges to ease maintenance as well as obscuring the road from surroundings and limiting proximity of housing to the road in future developments.
Page 101 of 132 Project Support Framework (Consultancy) 2011 – 2016 A27 Chichester Bypass Technical Appraisal Report
10 Environmental assessment 10.1 Introduction
The section below presents a summary of the assessment of potential environmental effects at both the construction and operational stage of the A27 Chichester Improvements. The assessment has been completed in accordance with the Design Manual for Roads and Bridges (DMRB), Volume 11 to a Scoping Level for all environmental topics contained within Volume 11, Section 3. The full assessment is presented within the Environmental Scoping Reports prepared by Mott MacDonald for both the online and offline options (March 2015)
10.2 Consultation with Statutory Environmental Bodies
Consultations with Statutory Environmental Bodies (SEBs) have been undertaken with English Heritage, Natural England, the Environment Agency, and the South Downs National Park Authority, during March 2015.
10.3 Noise
10.3.1 Online Options
Residential receptors have been identified within 600m of the proposed works. As a result, there is potential for adverse impacts arising from construction noise, particularly if activities are undertaken overnight. Potential impacts from construction noise are highly dependent on a number of factors such as working method, time of day, duration, the type of plant used and proximity to receptors. All of these factors combine to mean that there is the potential for exceedences over the background noise level during construction, for a sufficient period that may result in overall significant impacts. However, with the implementation of mitigation measures, such as those identified in Appendix 1/9 ‘Control of Noise and Vibration’ of the Specification for Highways Works and developed in consultation with the local Environmental Health Officer (EHO), significant effects during construction would be minimised.
The proposed online options will run directly through Noise Important Areas, located at Stockbridge roundabout, to the west and east of Whyke roundabout, and between Bognor Road and Portfield roundabout. In addition, two Noise Important Areas are located approximately 300m to the northwest of the proposed online options, in Fishbourne.
Once the scheme is implemented, there would be a change to the existing road layout and operating conditions. There is potential for traffic flow changes and the change in road alignment to result in a noise increase of greater than 1dB for residential receptors within close proximity of the road. Mitigation measures such as the inclusion of acoustic barriers and the application of low noise road surfacing may be required, particularly to reduce permanent effects upon the Noise Important Areas.
Page 102 of 132 Project Support Framework (Consultancy) 2011 – 2016 A27 Chichester Bypass Technical Appraisal Report
10.3.2 Offline Options
Construction and operational effects for the proposed offline options are anticipated to be similar to those outlined above for the online options. In addition, there is a Noise Important Area occupying a 1km stretch of the existing A27 through Tangmere, at the eastern extent of the proposed offline options.
10.3.3 Further Assessment
For both the online and offline options, the scope of the works and the potential significance of effects warrants further assessment to Detailed level as the Scheme meets the criteria as set out in the DMRB, Volume 11, Section 3, Part 7 for a Detailed Assessment to be undertaken for Noise and Vibration. In addition, Scheme options will be appraised in accordance with WebTAG Unit A3 Environmental Impact Appraisal, Noise Impacts.
10.4 Local Air Quality
10.4.1 Online Options
There are a number of sensitive receptors within 200m of the construction area. Based on the likely construction activities and their dust raising potential, the temporary nature of the construction phase and the location of sensitive receptors, potential dust impacts can be suitably controlled to avoid loss of amenity or nuisance using appropriate mitigation measures, which should be incorporated into a Construction Environmental Management Plan (CEMP) for the Scheme.
In addition, the proposed online options run through an Air Quality Management Area (AQMA) at Stockbridge roundabout, for which the Local Air Quality Action Plan should be referred to for specific requirements during works.
There are a number of receptors within 200m that may be affected during operation as changes in traffic flows may meet the affected roads criteria outlined above. On this basis the operational effect upon air quality receptors has the potential to be significant, and further assessment is considered necessary so as to fully determine the likely air quality impacts of the Scheme for nearby receptors and for the AQMA for all online options.
10.4.2 Offline Options
Construction and operational effects for the proposed offline options are anticipated to be similar to those outlined above for the proposed online options.
10.4.3 Further Assessment
For both the online and offline options, the scope of the works and the potential significance of effects warrants further assessment to Detailed level as the Scheme meets the criteria as set out in the DMRB, Volume 11, Section 3, Part 1 for a Detailed Assessment to be undertaken for Air Quality. In addition, Scheme options will be
Page 103 of 132 Project Support Framework (Consultancy) 2011 – 2016 A27 Chichester Bypass Technical Appraisal Report appraised in accordance with WebTAG Unit A3 Environmental Impact Appraisal, Air Quality Impacts.
10.5 Greenhouse Gases
10.5.1 Online and Offline Options
During construction, it is anticipated that there would be a net increase in greenhouse gasses (embodied carbon) associated with large scale construction works from both road improvements and the construction of new link roads, as well as for options that would be constructed entirely offline. However, once the scheme is in operation, it is anticipated that there would be a net reduction in greenhouse gas emissions due to increased fuel efficiency resulting from reduced congestion and improved traffic flows, for all scheme options.
10.5.2 Further Assessment
Scheme options will be appraised in accordance with WebTAG Unit A3 Environmental Impact Appraisal, Greenhouse Gasses.
10.6 Landscape and Townscape
10.6.1 Online Options
Vegetation clearance would be required within some of the verges to allow the construction of infrastructure and below ground cabling, which would result in the opening up of views of the road to nearby receptors.
There are numerous residential and commercial properties and public rights of way (PRoW) adjacent to the Scheme, and the presence of construction plant and the provision of construction lighting would subsequently result in a moderate change in the local landscape character for a temporary period. Since the landscape is considered to be of high value, impacts associated with construction are considered to be Potentially Significant.
The proposed Stockbridge Link Road included as part of Options 2 and 15, and the extended Stockbridge Link Road included as part of Option 2, would extend the existing highways corridor and there would be a direct impact upon land outside of this boundary. The local landscape character would be altered as a result of the proposed Scheme. Once implemented, the works at existing junctions and addition of the link roads may interrupt key views from the south to Chichester Cathedral from Chichester Harbour Area of Outstanding Natural Beauty (AONB).
10.6.2 Offline Options
Construction effects of the proposed offline options are anticipated to be similar to those outlined above for the online options.
Page 104 of 132 Project Support Framework (Consultancy) 2011 – 2016 A27 Chichester Bypass Technical Appraisal Report
During operation, due to the elevated topography, it is likely that the majority of Routes A to D would be visible from the South Downs National Park (SDNP), with residual adverse effects (without mitigation) upon the character of this nationally significant area and for visual receptors within the locality. In addition, Routes A and C would encroach into the SDNP slightly, to the north of Tangmere. Despite the flatter topography to the south of Chichester, the presence of the new carriageways and related signage and infrastructure associated with Routes E to J may still result in adverse effects for visual receptors and upon the landscape character. Measures to minimise effects may be required such as screening planting and earth bunds, which would be fully integrated as part of the Scheme design.
10.6.3 Further Assessment
The scope of the works and the potential significance of effects require further assessment as the Scheme meets the criteria as set out in the DMRB, Volume 11, Section 3, Part 5 and IAN 135/10 for a Detailed Assessment to be undertaken for visual impact and landscape character. In addition, Scheme options will be appraised in accordance with WebTAG Unit A3 Environmental Impact Appraisal, Impacts on Landscape and Townscape.
10.7 Heritage and Historic Resources
10.7.1 Online Options
The works associated with the online options would encroach beyond the highways boundary, particularly the proposed link roads included as part of Options 2 and 15, and as a result there could be buried archaeological remains discovered during the construction phase. There is also the potential for significant adverse impacts on the setting of Listed Buildings.
Consultation with Chichester District Council (CDC) carried out for the Project Review Report (HA, 2014) indicated that while impacts to previously unknown archaeological remains are likely, it is not expected that any previously unknown archaeological remains would be of high value, thus limiting the risk for significant adverse effects. However, there is the potential for Slight Adverse effects on the setting on Listed Buildings during operation.
10.7.2 Offline Options
The construction of new infrastructure on previously undeveloped land, such as has been proposed for all the offline route options, has the highest potential for significant effects upon the historic environment. The risk is particularly high for the proposed Routes C, D and E, which pass through the Chichester Dyke Broyle earthwork SAM (Routes C and D) and adjacent to Fishbourne Roman Palace SAM (Route E). Other than the tie-in points to the existing A27, all of the proposed works for the offline options would encroach beyond the highways boundary, and as a result, the potential for buried archaeological remains to be unearthed is high.
Page 105 of 132 Project Support Framework (Consultancy) 2011 – 2016 A27 Chichester Bypass Technical Appraisal Report
Routes C and D would have a Large Adverse effect during operation, as they would pass through the Chichester Dyke Broyle earthwork, which would be permanently damaged. During operation of Routes A, B, E, F, G, H and J there is the potential for the setting of SAMs and Listed Buildings to be affected. There is therefore the potential for Moderate to Large Adverse effects on the setting of these SAMs (without mitigation), which are considered to be potentially significant.
10.7.3 Further Assessment
The scope of the works and the potential significance of effects warrant further assessment as the Scheme does not meet the criteria as set out in the DMRB, Volume 11, Section 3, Part 2 for a Simple Assessment to be undertaken for Cultural Heritage. In addition, Scheme options will be appraised in accordance with WebTAG Unit A3 Environmental Impact Appraisal, Impacts on the Historic Environment.
10.8 Biodiversity
10.8.1 Online Options
Prior to construction works, vegetation clearance is likely to be required, with the potential to affect habitats of biodiversity value. There is the potential for contaminated runoff from the construction site to be carried downstream to the designated sites. In addition, there could be habitat loss or fragmentation (although not directly to the designated sites) if either of the options to construct the Stockbridge Link Road (Options 2 and 15), and the extended Stockbridge Link Road (Option 2), are progressed. Impacts upon biodiversity, which includes designated sites that are receptors of Very High value, are therefore considered to be Potentially Significant. Works within the verge would impact upon areas of habitat which have the potential for protected species and as a result, surveys to establish the presence or absence of these species would be required.
After construction work and during the operation of the Scheme, Options 1, 11, 13 and 19 are considered likely to pose a Neutral effect to Nature Conservation, although this would need to be reviewed following the completion of the protected species surveys. However, the provision of the new Stockbridge Link Road (Option 15) and the extended Bognor/Whyke Link Road (Option 2) would result in the permanent loss and severance of habitat that is of potential biodiversity value.
10.8.2 Offline Options
Construction effects for the proposed offline options are anticipated to be similar to those outlined above for the proposed online options.
During operation, there would be a permanent loss and potential severance of habitats of biodiversity value. The permanent removal of areas of habitat suitable for protected species though the construction of new carriageways (Routes A to J) has the potential to adversely affect their conservation status. As a result, it is anticipated that there is the potential for a Potentially Significant effect upon nature conservation features once the Scheme has been constructed. Ecological mitigation and potential compensation is likely
Page 106 of 132 Project Support Framework (Consultancy) 2011 – 2016 A27 Chichester Bypass Technical Appraisal Report to be required, and would be developed through the implementation of a detailed ecological mitigation strategy, incorporating a No Net Loss of biodiversity approach.
10.8.3 Further Assessment
The scope of the works and the potential significance of effects warrant further assessment to Detailed level, as the Scheme meets the criteria as set out in the DMRB, Volume 11, Section 3, Part 4 and IAN 130 / 10 for a Detailed Assessment for Nature Conservation. In addition, Scheme options will be appraised in accordance with WebTAG Unit A3 Environmental Impact Appraisal, Impacts on Biodiversity.
10.9 Water Environment
10.9.1 Online Options
Construction activities have the potential to increase the risk of a pollution incident at the site of works, associated with contaminated land or spills/ leaks of oils and fuels. Disturbance of contaminated land and the improper storage of construction materials could result in runoff and subsequent pollution of the drainage channels and watercourses that pass under the A27 if not properly mitigated. However, if best practice working methodology is employed in accordance with CIRIA C532 Control of Water Pollution from construction sites, then this risk is considered to be low, and there would be no residual impact upon drainage and the water environment as a result of the Scheme.
During operation, the road drainage would be altered as a result of the Scheme as the roadside verge could be hardened in a number of locations if additional lanes are installed. However, once installed, with the new drainage in place which would be developed in accordance with HD 33/06, the additional lanes are not anticipated to result in any actual increase in flood risk at the outfalls.
The proposed new Stockbridge Link Road (included as part of Options 2 and 15), and the extended Stockbridge Link Road (included as part of Option 2) would also increase the area of impermeable surfacing, thus introducing a potential increase in flood risk. In addition, the Stockbridge Link Road would cross the main River Lavant and its associated Flood Zones 2 and 3, which could cause an increase in flood risk to the surrounding area due to increased surface water run-off and/or reduction in flood plain storage.
10.9.2 Offline Options
As detailed above for the proposed online options, construction activities associated with the risk of pollution are also anticipated for the proposed offline options.
As with route Options 2 and 15, the proposed new offline option carriageways would increase the area of impermeable surfacing, thus introducing a potential increase in flood risk. In addition, Routes A, B, C, and D cross the River Lavant and its associated Flood Zones 2 and 3, and Routes E, F, G, H and J would also cross Flood Zones 2 and 3, which could cause an increase in flood risk to the surrounding area due to increased surface water run-off and/or reduction in flood plain storage.
Page 107 of 132 Project Support Framework (Consultancy) 2011 – 2016 A27 Chichester Bypass Technical Appraisal Report
10.9.3 Further Assessment
Due to the location of the proposed works in relation to the River Lavant, Chichester Canal, Fishbourne Stream, Pagham Harbour Waterbody and the Chichester-Worthing- Portsdown Chalk groundwater body, a Preliminary Water Framework Directive assessment (WFDa) should be carried out, to ensure the proposed Scheme would not have an adverse effect on the WFD status of those waterbodies.
The scope of the works and the potential non-significant effects warrant further assessment as the Scheme meets the criteria as set out in the DMRB, Volume 11, Section 3, Part 10 for a Detailed Assessment to be undertaken for Road Drainage and the Water Environment. In addition, Scheme options will be appraised in accordance with WebTAG Unit A3 Environmental Impact Appraisal, Impacts on the Water Environment.
Page 108 of 132 Project Support Framework (Consultancy) 2011 – 2016 A27 Chichester Bypass Technical Appraisal Report
11 Assessment Summary 11.1 Appraisal Summary Tables (AST)
At this stage the Traffic Model required for the production of the Appraisal Summary Tables have not yet been completed. Options Assessment Framework Tables have been created to substitute these at this early stage, and shall be used during Stage 2 to create the Appraisal Summary Tables. These tables can be found in Appendix E – Options Assessment Framework Tables.
11.2 Summary of consultation with public bodies
Stakeholder engagement has been a key aspect of the options generation and development process, for the verification of the evidence base and the agreement of the intervention-specific objectives.
The approach taken during this Stage 1 of the appraisal process was to ensure that all three main components of the engagement: consultation, participation and information are covered on an on-going basis in a distinguished manner for all interested parties throughout this stage.
The process was started after project inception with inputs provided by the local authorities West Sussex County Council (WSCC) and Chichester District Council (CDC) in the project objectives detailed in the previous section above. These inputs have been fundamental in shaping the approach taken in options identification and their subsequent development and acceptability.
Two main channels of engagements with the local authorities had been put in place in order to ensure a structured approach with good participation from both WSCC and CDC during Stage 1assessment:
• The first channel was through a number of workshops, intended to promote consultations at particular stages in the options development stage and seek views from elected members of the WSCC and CDC as key representatives of the general public. • The second one was through the establishment of the A27 Focus Group – a steering group set up to foster and facilitate participation of key members from the two organisations into main project decisions with direct influence on the outcomes of the options identification and development.
In addition to these, engagement of the Statutory Environment Bodies was also progressed in parallel through an Environmental Liaison Group.
Page 109 of 132
Project Support Framework (Consultancy) 2011 – 2016 A27 Chichester Bypass Technical Appraisal Report
13 Conclusion and Recommendations 13.1 Summary of option sifting results
From the sifting process, Option 19, Route E, Option G and Option J were identified as the least performing options. Option 19 – an online improvement option, despite indicating good value for money, appears to fail to address congestion in advance of the design year (2034) with some junctions even operating at capacity in 2014. Route E – a complete offline route to the south on Chichester and Option G – a hybrid option combining online improvements to some junctions , followed by an offline segment to the south of Chichester and Option J – another hybrid option but with more extensive offline construction, scored moderately well against congestion and other associated issues. However, both show significant adverse environmental impacts due to their southerly route alignments and were considered to be poor value for money due to the high capital costs incurred through the difficult ground conditions to the south of Chichester.
From the sifting process, the rest of the offline options (Routes A, B, C and D) were found to perform most favourably against the project objectives as they all generally scored well against reducing strategic and local congestion, as well as against safety, buildability and economy aspects. The area these options score poorly are the impacts on the environment, both in reducing adverse environmental impacts and tackling climate change, due to the large extent of new dual carriageway they would implement.
Route A and Route C are the least favourable of the four northern offline options as they are longer in length so prove less value for money and intrude more upon the South Downs National Park. Furthermore, it is considered that some of the problems Route A and Route C resolve could be overcome more cost effectively and less intrusively by Route B and Route D. Therefore, due to the similarity of all northern offline options, it was decided to rationalise the number taken forward into the Stage 2 process from this category type to only the two best performing northern offline options (Route B and Route D).
Option W, Option 1 and Option 2, all online options, were the better performing options after the northern offline options. Option 1 scored favourably against reducing strategic and local congestion and economic aspects as well as minimising the adverse impact on the environment due to being an online option. Although Option W scored less favourably against reducing strategic and local congestion when compared with Option 1, the limited scope of the works scored better against reducing adverse environmental impacts and tackling climate change which improved the overall score of this option. Option 2 provides a novel solution for removing the Stockbridge and Whyke junctions along the existing Chichester Bypass, by providing an extended Stockbridge Link Road, the shortened version of which gained some approval at the previous Public Consultation. Option 2 should reduce strategic congestion, improve connectivity and has the potential to be lower impact than an offline option.
The results of the sifting process identified a clear separation between the better performing options and the remaining other options. The better performing options were
Page 114 of 132 Project Support Framework (Consultancy) 2011 – 2016 A27 Chichester Bypass Technical Appraisal Report encompassing online improvements and fully offline options to the north of Chichester. However, these options alone were not considered to provide a representative sample of options for taking forward to the Stage 2 process and as such the short-list was expanded.
In order to improve the range of options, it was considered appropriate to include in the short-list, the best performing hybrid option (Route H), as this allowed an alternative option type as well as an offline component to the south of Chichester to be tested alongside the better performing options. Similarly, previous public consultation in 2005 showed strong support for the Stockbridge Link Road and as such, it was also considered appropriate for this reason as well to take this option forward to the Stage 2 process in order to fully test the potential benefits of the Stockbridge Link road alongside the better performing options.
13.2 Options to be taken to Stage 2
The results of the two stage sifting process show that the following options are identified as the better performing options when assessed against both the EAST criteria and the specific project objectives, therefore it is considered these are worthy of further consideration and as such will be taken forward to the WebTAG Stage 2 – Further Appraisal process for further consideration:
° Route B – offline bypass route to the North of Chichester; ° Route D – offline bypass route to the North of Chichester; ° Option 1 – online junction improvements including grade separation at some of the junctions and signalised cross-roads with banned turning movements at others; ° Option 2 - online junction improvements including grade separation and flyover arrangements at some of the junctions with banned turning movements at others. Construction of a new link road between Fishbourne junction and Whyke is also proposed with this option; ° Route H – hybrid option with grade separation and flyover arrangements at some of the junctions followed by a new alignment diverging offline to the south of Chichester between Whyke and Bognor road junctions and connecting back into existing A27 prior to the existing interchange with the A285 at Tangmere. Construction of a new link road between Fishbourne junction and Whyke is also proposed with this option; ° Option W – low cost online scheme improvements considering primarily introduction of traffic signals to most of the existing junctions with banned turning movement; and
Page 115 of 132 Project Support Framework (Consultancy) 2011 – 2016 A27 Chichester Bypass Technical Appraisal Report
14 Detailed cost estimate
A cost estimate has been produced by Highway England’s commercial partners, Benchmark. The formal output of this has been submitted directly to Highways England as a PCF product, however the summary of the costs is provided below.
14.1 Assumptions
• All base estimate information priced at Quarter 1,2014 • Historical Costs taken from end of Feb 15 • Options costs as per budget submissions • Development phase costs worked up from an assessed number of FTE equivalents for each option, for durations set by the SGAR dates provided • Land costs were provided for the offline routes. These were provided exclusive of inflation. Inflation applied from April 2015 for SOW Feb 2018. • Indirect Works – Construction durations provided by project team used to determine the duration for overhead and method related costs. Prelims priced using Commercial Services Division’s Preliminaries Costs Model. • Where applicable, the C3 Estimates shown in Section 3.12.10 have been included in the below costs.
• Direct Works – For each option, the following approach was taken: o Option 1 – Online junction improvements to existing A27 Junction improvement works taken off drawing in on-screen take-off and bid using the Q1,2014 database. Take off was completed in Feb 2014. No scope change has occurred in the meantime, therefore previous work is still fit for purpose.
o Route A – Offline bypass to the North of Chichester Route created using the Roadworks Estimator software with option information being provided by the project team. The scheme has been priced using the Q1,2014 database.
o Route B – Offline bypass to the North of Chichester Route created using the Roadworks Estimator software with option information being provided by the project team. The scheme has been priced using the Q1,2014 database.
o Route C – Offline bypass to the North of Chichester Route created using the Roadworks Estimator software with option information being provided by the project team. The scheme has been priced using the Q1,2014 database.
o Route D – Offline bypass to the North of Chichester Route created using the Roadworks Estimator software with option information being provided by the project team. The scheme has been priced using the Q1,2014 database.
Page 116 of 132 Project Support Framework (Consultancy) 2011 – 2016 A27 Chichester Bypass Technical Appraisal Report
o Route H – Offline bypass to the South of Chichester, Stockbridge Link Road & Online junction improvements to existing A27. Option H and Stockbridge Link Road Route created using the Roadworks Estimator software with option information being provided by the project team. The scheme has been priced using the Q1,2014 database. The online works taken off drawing in on-screen take-off. Take off was completed in Feb 2014. No scope change has occurred in the meantime, therefore previous work is still fit for purpose.
o Option W - Online junction improvements to existing A27 Junction improvement works taken off drawing in on-screen take-off and bid using the Q1,2014 database. Take off was completed in Feb 2014. No scope change has occurred in the meantime, therefore previous work is still fit for purpose.
o Option 2 – Online junction improvements to existing A27 Junction improvement works taken off drawing in on-screen take-off and bid using the Q1,2014 database. Take off was completed in Feb 2014. No scope change has occurred in the meantime, therefore previous work is still fit for purpose.
• Stage 6 Employers Agent cost worked up from an assessed number of FTE equivalents for each option, for the construction durations provided • Contractor Fee has been set at 10% in the absence of a known rate. This is the default percentage used by Commercial Services Division at early stages
• Statutory Undertakers o Online Junction Improvements ° C3 estimates provided by the project team o Offline Routes ° Percentage of the Cost of Construction used. Percentages used are: • Minimum – 1% of the Minimum CoC • Most Likely – 2% of the Most Likely CoC • Maximum – 3% of the Maximum CoC
• NR VAT o Offline Routes are at 95%, of the value of works outside the highways boundary o Online works are at 15% for Option 1 & 10% for the W Option, of the value of works outside the highways boundary
• Risk o A single Risk Register was provided from the project team which had been scored but not priced
Page 117 of 132
Project Support Framework (Consultancy) 2011 – 2016 A27 Chichester Bypass Technical Appraisal Report
The options estimate summary table above excludes costs for Options A and C, since these have been discounted in Stage 1, Step 7 and therefore not recommended for Stage 2 – Further Appraisal, as explained in Section 13.
Page 119 of 132 Project Support Framework (Consultancy) 2011 – 2016 A27 Chichester Bypass Technical Appraisal Report
Appendix A – Environmental Constraints Plan
Page 120 of 132
Project Support Framework (Consultancy) 2011 – 2016 A27 Chichester Bypass Technical Appraisal Report
Appendix C – Original Offline Route Options
Page 129 of 132 Project Support Framework (Consultancy) 2011 – 2016 A27 Chichester Bypass Technical Appraisal Report
Appendix D – Refined and Hybrid Offline Route Options
Page 130 of 132 Project Support Framework (Consultancy) 2011 – 2016 A27 Chichester Bypass Technical Appraisal Report
Appendix E – Options Assessment Framework Tables
Page 131 of 132 Project Support Framework (Consultancy) 2011 – 2016 A27 Chichester Bypass Technical Appraisal Report
15 References
CDC (2008) Air Quality Action Plan 2008, available online at http://www.chichester.gov.uk/CHttpHandler.ashx?id=6298&p=0, accessed 10/12/2014.
CDC (2014) 2014 Air Quality Progress Report for Chichester District Council: In fulfilment of Part IV of the Environment Act 1995 Local Air Quality Management, available online at http://www.chichester.gov.uk/CHttpHandler.ashx?id=22575&p=0, accessed 10/12/2014.
EA (2009) River Basin Management Plan South East River Basin District, available online at https://www.gov.uk/government/collections/river-basin-management-plans, accessed 10/12/2014.
EA (2012) River Lavant Flood Alleviation Scheme (part of Flood and coastal erosion risk management: current schemes and strategies and Reducing the threats of flooding and coastal change, available online at https://www.gov.uk/government/publications/river- lavant-flood-alleviation-scheme, accessed 05/12/2014.
Hume, V. and Grose, M. (2010) A revision of the Ancient Woodland Inventory for West Sussex, available online at http://sxbrc.org.uk/projects/revised-ancient-woodland- inventory/, accessed 05/12/2014.
NE (2014) NCA Profile: 126 South Coast Plain (NE525), available at http://publications.naturalengland.org.uk/publication/4923911250640896, accessed 05/12/2014.
Page 132 of 132