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Early plans to build tunnels as part of Highways England’s A417 “missing link” between Gloucester and Swindon was always “very questionable” due to the cost, according to Highways England South West regional delivery director Nick Aldworth.
Local campaign groups and MPs spent years fighting for the road to be put in a tunnel due to environmental concerns.
However, speaking at NCE's Future of Roads conference, Aldworth said that while tunnelling was considered as an option early in the development of the scheme, cost-wise it would have always posed challenges.
“At the start of RIS1 we had up to 30 potential routes and were talking about potential for tunnels and we didn’t do everything we should have done to set expectations," he said.
“A tunnel would have been very expensive - the value for money business case for a tunnel in this area would have been very questionable and I think it would have made it more difficult to make improvements to this road. So I would have started that one differently having had a chance.”
Last month the Planning Inspectorate accepted Highways England’s planning application for the project, which will ease congestion and improve safety on the route.
The project is valued between £250M and £500M and is an alternative to the M5/M4 route via Bristol. The missing link itself is a 5km stretch of single-lane carriageway on the A417 between the Brockworth bypass and Cowley roundabout in Gloucestershire.
It causes problems for road users, with congestion frequent and unpredictable. This means motorists to divert onto local roads to avoid tailbacks – but these roads were not built to accommodate high levels of traffic. Poor visibility and other factors lead to frequent accidents along this section of road.
A417 missing link plans include:
- 5.5km of new dual carriageway connecting the existing A417 Brockworth bypass with the existing A417 dual carriageway south of Cowley
- the section to the west of the existing Air Balloon roundabout would follow the existing A417 corridor
- the section to the south and east of the Air Balloon roundabout would be offline, away from the existing road corridor
- a new junction at Shab Hill, providing a link from the A417 to the A436 towards Oxford and into Birdlip
- a new junction near Cowley, replacing the existing Cowley roundabout
- the existing A417 between the Air Balloon roundabout and the Cowley roundabout repurposed - some lengths of this existing road converted into a route for walkers, cyclists and horse riders, while retaining other sections to maintain local access for residents
The scheme has been in the pipeline for 30 or 40 years and last month's planning approval is the furthest it has progressed, Aldworth said, adding that he is “proud” of the work that has been achieved on the scheme.
“This was a good project for how we managed to work with the key stakeholders,” he said. “It was a good example of collaboration and joint working.”
However the plans have not been without controversy.
According to Highways England, it would enable users of the Cotswold Way National Trail and Gloucestershire Way to safely cross the road.
However Transport Action Network said the plans for the crossing and the road itself would scar the Cotswolds area of natural beauty.
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Missing Link options
The central issue with the Missing Link is that traffic streams on the A417, A436 and a minor road to a country park entrance and Cheltenham conflict with each other at grade at the small Air Balloon roundabout, resulting in long queues every day. The roundabout’s location at the lip of the scarp slope of the Cotswolds means that it cannot be modified easily to give grade separation.
The design proposed includes the demolition of the best known public house in the Cotswolds, several kilometres of new road across a rural area, traffic on the A436 link to the A40 having to drive an extra 2km permanently to use a new roundabout and three years of construction work centred on the roundabout at the heart of the existing congestion.
To bring the Missing Link up to the standard of the rest of the A417 without all the disadvantages around the Air Balloon roundabout calls for a tunnel down through the scarp, not cheap, the reason why this section remains missing.
A cheaper option would be a pair of freeflow sliproads linking the two arms of the A417 to the west of the Air Balloon public house. If these were restricted to light traffic they could be smaller, steeper and cheaper than for full specification sliproads but would still remove 75% of traffic from the vicinity of the Air Balloon roundabout, which would not need any changes.
Neither of these two options would require any work at all at any time in the vicinity of the roundabout and pub or the extensive diversions which it must be suspected are looming.