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The Project Control Framework
This framework sets out how we, together with the Department for Transport, manage and deliver major road improvement projects.
A417 Cowley to Brockworth Bypass Improvement
14 RECOMMENDATIONS
14.1 Discussions with statutory and non-statutory bodies in the area have shown there is a need to improve the single carriageway section of the A417 trunk road. The study has been a pre-investment study which has aimed to identify if there are route improvement options which can be developed which do not have unacceptable environmental consequences and which can be supported by statutory environmental bodies. This study has been completed and three options have emerged from the process. Each has passed through an initial screening and "optioneering" process. This identified in broad terms that they met the study criteria and merited further assessment. This assessment has considered whether the options:
- are buildable;
- offer improvements over the existing situation;
- improve safety and congestion (for given periods); and
- are economically viable.
14.2 In environmental terms all three exhibit a mixture of potentially beneficial and adverse impacts. This is to be expected given the environmental sensitivity of the area, and the history of proposed improvements on this section of trunk road.
14.3 All three options need further design (vertical and horizontal alignments) and for more detailed traffic modelling to be undertaken. Results of this Stage 2 assessment would identify a preferred route. The recommendations which follow identify which of the options should be taken forward and identify where specialist environmental or geotechnical assessments will have to be undertaken.
14.4 Discussions with statutory environmental consultees have confirmed that all three options could proceed to the next stage in planning and design, albeit with a recognition that all of them require additional, more detailed, design and environmental assessment.
14.5 However, whilst no 'environmental showstoppers' have been identified for Options 1 and 2, there has been for Option 3, the tunnel. Discussions with the Environment Agency, English Nature and other bodies have identified serious concerns about Option 3, the tunnel, and the potential impact on the groundwater regime. At this stage the available information indicates that further detailed assessment of this option is unlikely to provide sufficiently conclusive data regarding the risks to the groundwater regime to permit the Environment Agency to remove their existing objection. At this stage it is sufficient reason not to take this option forward.
Option 1
14.6 Whilst it is recognised that this option is buildable, economic and provides some congestion relief, it does not provide a long term solution for road borne traffic within the study area due to limited capacity at the Air Balloon junction. In addition, there are serious concerns over safety on certain aspects of the layout which could not be overcome by careful detailed design. Although this option would improve the majority of the route the Air Balloon junction would continue to be a bottleneck and present safety problems. Whilst detailed design and modelling may be able to extend this congestion-free period by a few years, it is unlikely to provide a long term solution or overcome the safety concerns This option therefore fails to meet 2 of the main tenets of this study.
14.7 Of the options considered, Option 1 would result in the least environmental impact, would be quickest and cheapest to construct but also would provide the least benefit.
14.8 From the discussions held with the statutory environmental consultees, it was evident that further consideration of certain aspects would be required. In particular, the impact of the restructured Air Balloon Junction, the link roads on Crickley Hill and the proposed bypass of Nettleton were identified by the Countryside Agency and National Trust as being of importance. Lighting and landscape proposals would need significant input at these locations.
Recommendation
14.9 Consideration of the safety concerns, the limited lifetime of the scheme and the limited environmental benefits mean that Option 1 is not recommended to be taken forward for further design and assessment.
Option 2
14.10 Work completed to date indicates that this option is viable and provides a long-term safety and capacity improvement for road based traffic within the study area. It also offers the opportunity to provide improvements to non-motorised users in terms of access across the road particularly for the National Trails.
14.11 The pre-investment assessments have identified potential environmental impacts could occur and discussions with statutory environmental consultees have identified similar issues to Option 1 with regard to Crickley Hill, the Air Balloon and Nettleton. However, it has been recognised that relocation of the Air Balloon roundabout and grade separation offers potential opportunities to reduce the existing lighting impact at Air Balloon, especially with regard to Crickley Hill and the top of the scarp slope. The anticipated impacts can only be defined after a sensitive design is developed and agreed with key stakeholders in the process.
14.12 The bypass around Nettleton would also require sensitive design and assessment if unacceptable impacts on the AONB are to be avoided. Landscaping will be the key issue at this location.
14.13 Impacts on local air quality and noise and land-take issues will have to be addressed and mitigation measures designed if these are to be acceptable to local residents. However, it is believed that some of these can be reduced during detailed design and suitable mitigation measures designed once the type and quantum of impact are fully identified.
Recommendation
14.14 Discussions with statutory environmental bodies have confirmed that subject to further work this option can be taken forward for more detailed design and assessment. It is therefore recommended that this option be taken forward.
14.15 Options 1 and 2, as tested in this report, are either ends of a spectrum with regard to Crickley Hill and Air Balloon roundabout. Option 1 endeavours to maximise the utilisation of land within the existing highway boundary for the improved carriageways and involves the re-alignment of the existing lanes up Crickley Hill to provide two lanes up and two lanes down the hill. Option 2 is the opposite end of the spectrum requiring minimal interference with the existing carriageway and the provision of two new downhill lanes on Crickley Hill allowing a "three up and two down" option. The "two-up and two down" option with the grade separated roundabout option has also been considered and shown to work, therefore it is recommended that this alternative to Option 2 should also be tested using a detailed traffic model in the next stage.
Option 3
14.16 The assessment carried out to date on this option indicates that it is buildable, relieves the pressure on Crickley Hill and the Air Balloon roundabout and provides long term local safety and environmental improvements. Tunnel costs, however, cancel out the economic benefits so that it is on the border line of a viable scheme. Also, discussions with the environmental statutory bodies, and the Environment Agency in particular, have raised serious concerns about the potential impact on the underlying major aquifer. Both the police and fire services have raised additional safety concerns.
Recommendation
14.17 Whilst concerns have been raised by all the statutory consultees, the Environment Agency has entered a holding objection to the tunnel, pending provision of more detailed information on the potential impacts on the local (and potentially regional) groundwater regime. All the statutory bodies are content that the option be assessed further but, to overcome their concerns, significant further work would be required.
14.18 The additional information required by the Environment Agency would involve a phased risk assessment, and potentially computer modelling, to more accurately assess the risks of tunnel construction on the major aquifer, groundwater abstractions in the area, the impact on the Baunton source and the River Churn and the numerous springs along the scarp.
14.19 Given the nature of the underlying geology, there is a real possibility that to accurately define and model the groundwater regime over such a wide area will prove so difficult and problematic that, even after completion of the significant additional work, it may not be possible to be definitive about the impact of the tunnel. It is uncertain that even following this additional work the risks to the aquifer could be reduced to a level that would be acceptable to the Environment Agency, and for them to remove their objection. In these circumstances, the Environment Agency would be unlikely to withdraw their objection and would hold the Highways Agency legally responsible should environmental problems arise during construction and operation of the tunnel The Highways Agency could not accept such a condition.
14.20 It is recommended that at this stage no further assessment of this option is carried out.
