Part 7: Conclusion and Recommendation 24 Conclusion and Recommendation 24.1 Introduction 24.2 Engineering Conclusion 24.3 Environmental Conclusion 24.4 Traffic and Economic Conclusion 24.5 Sustainability Conclusion 24.6 Conformity with Scheme Objectives 24.7 South Route Corridor Option 4B 24.8 DMRB Stage 2 Corridor Report Recommendation
Part 7: Conclusion and Recommendation
24 Conclusion and Recommendation
24.1 Introduction
24.1.1 This chapter shall identify preferred northern and southern route corridor options to be taken forward for DMRB Stage 3 assessment. The recommendation made by this DMRB Stage 2 Corridor Report is based upon the requirements of the scheme objectives and the assessment work undertaken to date from an engineering, environmental, traffic, economic and sustainability perspective. The mainline route corridor options were developed to current standards over their full length. It is recognised that shorter improvements within each corridor are feasible. The full scope of improvement within the preferred corridor will be considered at the next stage of the study.
24.2 Engineering Conclusion
24.2.1 In terms of engineering assessment there is nothing which would preclude any of the options from being promoted, however North Corridor Option 1 and South Corridor Option 1 are deemed to be the preferable corridor options.
24.2.2 North Corridor Option 1 is preferable to North Corridor Option 2 as it maximises the use of existing roads infrastructure, improves the carriageway provision to dual three lane motorway and improves connectivity with new and improved junction arrangements. The provision of North Corridor Option 1 also represents value for money.
24.2.3 Likewise, South Corridor Option 1 is preferable to South Corridor Option 2 as it requires a shorter length of construction and maximises the use existing roads infrastructure whilst making provision for junction improvements. Like North Corridor Option 1, South Corridor Option 1 represents value for money.
24.3 Environmental Conclusion
24.3.1 Although the likely significance of environmental impacts differs between route corridor options, no environmental issues which would preclude the promotion of any of the options assessed have been identified through Stage 2 assessment.
24.3.2 Overall, North Corridor Option 1 is considered preferable to North Corridor Option 2 in environmental terms as the majority of the corridor is online. North Corridor Option 1 would affect fewer land interests, cross fewer pedestrian/cyclist routes, have less ecological impact and lower potential for impacts on sites of geological importance. In terms of watercourses, there are a similar number of crossings however North Corridor Option 1 is likely to have less potential for flood risk and water quality impacts and is therefore preferred overall. Noise and air quality impacts would be similar for either northern route corridor option. There is predicted to be virtually no change in local air quality, and although both options would result in both beneficial and adverse changes in noise levels, on balance North Corridor Option 1 is considered to be preferable. The predominantly online alignment of North Corridor Option 1 would also result in lower landscape and visual change and be preferable in terms of view from the road and driver stress. Although North Corridor Option 1 is closer to a Scheduled Ancient Monument (Middlebank Souterrain) than North Corridor Option 2, it is considered that potential impacts could be mitigated through design refinement as part of the DMRB Stage 3 assessment process.
24.3.3 Overall, South Corridor Option 1 is considered preferable to South Corridor Option 2 in environmental terms as it requires less new infrastructure and passes through less sensitive areas. South Corridor Option 1 would affect fewer land interests, fewer pedestrian/cyclist routes, have less ecological impact and lower potential to encounter contaminated land during construction. In terms of watercourses, South Corridor Option 1 would also require less flood risk mitigation, result in fewer water crossings, and is considered to have the least impact on water quality. Air quality impacts would be similar for either southern route corridor option. However, South Corridor Option 2 is the preferred option in terms of overall noise effects as it would divert traffic away from the A90 south of South Queensferry, although it would result in noise increases for a small number of rural properties. South Corridor Option 1 is preferred in terms of landscape and visual impacts as it is much more contained and in contrast to South Corridor Option 2 does not cut through open, rural landscape. South Corridor Option 2 would also increase landscape isolation of Dundas Estate due to encircling by roads infrastructure although in terms of cultural heritage South Corridor Option 1 would have a slightly higher impact due to direct loss of part of the Dundas Castle Designed Landscape.
24.4 Traffic and Economic Conclusion
24.4.1 In comparing the economic evaluation of Corridor Option combinations, under South Corridor Option 2 it is noted that a proportion of Edinburgh bound traffic would assign to the A904 as a more direct route from the Forth Replacement Crossing to Scotstoun Junction and Edinburgh via the A90, leaking from the new strategic network linking to the M9 and M9 Spur. The attributed traffic cost benefits, including the benefits attributed to the traffic from Fife using the A904, results in a higher Net Present Value (NPV). However, South Corridor Option 2 also comes with a substantial additional cost and therefore a broadly equivalent Benefit to Cost Ratio (BCR) in comparison to those option combinations containing South Corridor Option 1.
24.4.2 Given the additional cost associated with South Corridor Option 2 and its similarity with South Corridor Option 1 in terms of BCR, it was concluded that North Corridor Option 1 paired with South Corridor Option 1 would offer, overall, the preferred solution.
24.5 Sustainability Conclusion
24.5.1 The high level evaluation of the northern and southern route corridor options against the key DMRB Stage 2 sustainability objectives shows that North Corridor Option 1 and South Corridor Option 1 are preferred route corridor options for further assessment.
24.6 Conformity with Scheme Objectives
- to maintain cross-Forth transport links for all modes to at least the level of service offered in 2006
Northern Route Corridor Options
24.6.1 North Corridor Option 1 and North Corridor Option 2 satisfy the requirement of maintaining cross-Forth transport links to at least the level of service offered in 2006. Each provides two general traffic lanes each direction and is capable of making provision for future transport modes. Through the online upgrade of the A90/M90, North Corridor Option 1 is deemed to be preferable as it continues to utilise junctions at Ferrytoll, Admiralty and Masterton each providing access between the local communities of west Fife and the proposed mainline carriageway. North Corridor Option 2 does not provide the same level of functionality.
Southern Route Corridor Options
24.6.2 South Corridor Option 1 and South Corridor Option 2 both satisfy this scheme objective. South Corridor Option 2 satisfies this objective through the provision of a direct motorway connection to the M9 north of Winchburgh. South Corridor Option 1 is deemed to be preferable however as it makes best use of the existing roads infrastructure associated with the Forth Road Bridge, effectively extending the A90/M9 Spur connection to the proposed replacement bridge.
- to connect to the strategic transport network to aid optimisation of the network as a whole
Northern Route Corridor Options
24.6.3 North Corridor Option 1 and North Corridor Option 2 meet this objective through the provision of upgrades to the existing trunk road network. Both options provide an improved level of service when compared to the existing network through the implementation of a standardised cross section. Complementary initiatives such as High Occupancy Vehicle (HOV) lanes and Intelligent Transport Systems (ITS) can be used to support capacity management. Provision is also made for future public transport initiatives. In the optimisation of the trunk road and local road network as a whole, North Corridor Option 1 is deemed preferable with direct connections maintained between the proposed mainline and the A985, A921 and A823(M).
Southern Route Corridor Options
24.6.4 South Corridor Option 1 and South Corridor Option 2 are both capable of satisfying this objective through there connections to the A90, M9 Spur and M9 respectively. Both implement standardised cross sections and are capable of optimising the road network as a whole through the provision of new and improved junction arrangements. Complementary initiatives such as HOV lanes and ITS can be used to support capacity management.
- to improve the reliability of journey times for all modes
Northern Route Corridor Options
24.6.5 North Corridor Option 1 and North Corridor Option 2 satisfy this objective through the provision of a new/upgraded mainline carriageway to motorway standard. The provision of ITS shall assist journey time reliability. Whilst both options are deemed to bring benefits over the existing situation for all modes, North Corridor Option 1 through the provision of direct connections to existing routes such as the A985, A921 and A823(M) is deemed preferable.
Southern Route Corridor Options
24.6.6 South Corridor Option 1 and South Corridor Option 2 satisfy this objective through the provision of a new mainline carriageway to motorway standard. The provision of new and improved junctions shall assist in the effective operation of the route corridors. The provision of ITS shall aid journey time reliability.
- to increase travel choices and improve integration across modes to encourage modal shift of people and goods
Northern Route Corridor Options
24.6.7 North Corridor Option 1 and North Corridor Option 2 are both capable of increasing travel choices and encouraging modal shift. Each option has been designed taking cognisance of Park and Ride/Choose facilities in west Fife whilst also providing access to local destinations such as North Queensferry, Rosyth, Rosyth Dockyard, Inverkeithing and Dunfermline. The provision within each design for complementary measures and future public transport initiatives such as LRT, BRT, guided buses or trams will also encourage modal shift and assist capacity management in the future years if implemented.
Southern Route Corridor Options
24.6.8 South Corridor Option 1 and South Corridor Option 2 are also capable of increasing travel choices and encouraging modal shift. Each is capable of providing access to local and national destinations including South Queensferry, Dalmeny, the Lothians and the west of Scotland through the provision of new/improved junctions to local and national routes. The provision of complementary measures will be of benefit in the early years of the operation. Future public transport initiatives such as LRT, BRT, guided buses or trams will further encourage modal shift and assist capacity management in the future years if implemented.
- to improve accessibility and social inclusion
Northern Route Corridor Options
24.6.9 North Corridor Option 1 and North Corridor Option 2 are both capable of improving accessibility and social inclusion through the provision of a standardised carriageway cross section, new/improved junction arrangements and complementary measures. Each option also makes provision for future public transport modes which might be implemented. North Corridor Option 1 is deemed to be the preferred option as it offers direct connections between the trunk road and local road network through the use of Ferrytoll, Admiralty and Masterton Junction. North Corridor Option 2 whilst providing improvements does not provide the same level of direct accessibility as North Corridor Option 1.
Southern Route Corridor Options
24.6.10 South Corridor Option 1 and South Corridor Option 2 are both capable of improving accessibility and social inclusion through their connections to existing local and national routes. The provision of a standardised carriageway cross section and new/improved junction arrangements in addition to complementary measures will improve cross-Forth accessibility. The provision made within each design for future public transport systems such as LRT, BRT, guided buses or trams shall also assist each option in meeting this objective.
- to minimise the impacts of maintenance on the effective operation of the transport network;
Northern Route Corridor Options
24.6.11 North Corridor Option 1 and North Corridor Option 2 both satisfy this objective through the provision of a standardised carriageway cross section and ITS. Each has the ability to maintain two lanes of general traffic in each direction at all times. North Corridor Option 1 is deemed to be preferable as the provision of a dual three lane motorway enables one trafficked lane to be closed for maintenance on each carriageway whilst maintaining two lanes for general use without the need for contra flow running. Any sustained period of maintenance required on North Corridor Option 2 would likely have a greater impact on the operation of the local road network.
Southern Route Corridor Options
24.6.12 Like North Corridor Option 1, South Corridor Option 1 and South Corridor Option 2 both satisfy this objective through the provision of a standardised cross section and ITS. Both options provide dual three lane motorway cross sections, allowing two lanes of general traffic to be maintained at all times. South Corridor Option 1 is deemed to be preferable as it provides the shortest connection to existing infrastructure, limiting the impact that any maintenance period might have.
- to support sustainable development and growth
Northern Route Corridor Options
24.6.13 North Corridor Option 1 and North Corridor Option 2 support sustainable development and growth through their proposed improvements to the trunk road network. The provision of mainline carriageway to motorway standard and the incorporation of complementary measures will assist the development and growth of west Fife and beyond. The functionality provided for the implementation of future transport modes also supports this objective. New/improved junction arrangements will also provide benefits, improving connectivity between local and national routes.
Southern Route Corridor Options
24.6.14 South Corridor Option 1 and South Corridor Option 2 also support sustainable development and growth through their proposed improvements to the trunk road network. The provision of mainline carriageway to motorway standard and the incorporation of complementary measures will assist the development and growth of West Lothian, the Edinburgh area and beyond. The functionality provided for the implementation of future transport modes also supports this objective. New/improved junction arrangements will also provide benefits, improving connectivity between local and national routes.
- to minimise the impact on people, and the natural and cultural heritage of the Forth area.
Northern Route Corridor Options
24.6.15 North Corridor Option 1 is preferable to North Corridor Option 2 as it has the least impacts. It potentially has a lower impact on sites of geomorphological/geological importance, the least ecological impact and the least impact on the existing landscape. Furthermore, when compared to North Corridor Option 2, North Corridor Option 1 will bring minimal change visually, will have the least increase in traffic noise and vibration and imposes a lower level of driver stress. In addition, North Corridor Option 1 has less of an impact on footpaths and has the least potential for conflict with policies and plans.
Southern Route Corridor Options
24.6.16 South Corridor Option 1 is preferable to South Corridor Option 2 as it has least impact on land use, requires less flood risk mitigation, has the least ecological impact, has less impact on the landscape, is less visually intrusive and has less of an impact on footpaths. Furthermore, it will cause less disruption during construction when compared to South Corridor Option 2 and has the least potential for conflict with policies and plans.
24.7 South Route Corridor Option 4B
24.7.1 With reference to Part 6: South Route Corridor — Combination Option Assessment and South Corridor Option 4B, the land take associated with the implementation of such a scheme would be far higher than that associated with South Corridor Option 1 or South Corridor Option 2 and would be expected to have higher overall delivery environmental impacts.
24.7.2 The anticipated cost associated with the implementation of South Corridor Option 4B would be comparable to that of South Corridor Option 2 and far higher than that of South Corridor Option 1.
24.7.3 Considering the environmental impacts, the cost associated with this options implementation and the amount of existing roads infrastructure made redundant through its provision, South Corridor Option 4B was not taken forward.
24.8 DMRB Stage 2 Corridor Report Recommendation
24.8.1 On the basis of the foregoing analysis, the recommendation of this DMRB Stage 2 Corridor Report is that North Corridor Option 1 and South Corridor Option 1 be taken forward as the preferred corridors.
24.8.2 For the purposes of DMRB Stage 2 assessment, the route corridor options discussed within this report have been considered over the full extents of the Forth Replacement Crossing study area. The preferred corridor identified need not be implemented in full. As a part of the next stage of design and assessment, further detailed consideration shall be given to the form and function of the junctions required and the extent of the road infrastructure improvements provided within the preferred corridors. The developing design shall also reflect future consideration of the use of the Forth Road Bridge.