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A350 highway improvements

A350 Works Progress (30/11/17) 4

Upcoming Work on A350 Improvements

As we head into spring work keeps moving ahead on the A350 highway improvements in Chippenham. The next couple of months will see traffic changes around Chequers roundabout with vehicles moved onto the newly constructed highway north of the roundabout. Work will also be starting on the A4 west of the roundabout, this work will be undertaken at night under temporary traffic signals.

Upcoming Traffic Management Programme:

The next couple of months will see a number of changes to the traffic management and layout of roads along the A350 in Chippenham, below is the upcoming changes.

Week Commencing 16th April 2018: Traffic switch between Chequers & Cepen park North roundabout. This change will once again see traffic moved to the outside lanes to allow for work to take place on the new central reserve.

Week Commencing 16th April 2018: There will be a short term closure of the North side of Chequers roundabout to accomodate this work. This will result in a short diversion up to Cepen Park North roundabout and then back down to Chequers roundabout. The work is required to connect drainage systems into the centre of the roundabout. It is anticipated that this work will take 1-2 days to complete.

Week Commencing 23rd April 2018: (Following completion of work above): Night time works on the A4 (West arm) of Chequers roundabout. This work will be undertaken under temporary traffic signals between the hours of 8pm and 6am.

Week Commencing 7th May 2018: Traffic switch North of Cepen Park roundabout. This traffic switch will once again enable work to take place through the central reserve of the road. Whilst traffic occupies the outside lanes.

Week Commencing 21st May 2018: Traffic switch South of Chequers roundabout. The final traffic switch will see traffic moved to the outside lanes of the A350 whilst work is undertaken on the central reserve.

For further updates of traffic changes and updates please follow @WiltshireRoads on Twitter.


The improvements to the A350 Chippenham bypass will involve:

  • Widening the A350 to dual two-lane between Badger and Brook roundabouts, and between Cepen Park South and Chequers roundabouts.
  • Additional widening of the A350 for approximately 250 metres north of Cepen Park South and 250 metres immediately south of Chequers, to allow for suitable merge lengths back to single lane running and to allow for two lanes on the A350 approaches to the roundabouts.
  • As part of the widening to the south of Chequers, a new formal segregated layby will be provided on the northbound carriageway to replace the existing unsegregated layby.
  • Widening the A4 Bath Road westbound approach to Chequers, along with widening the A4 westbound exit, providing two lanes across the junction for A4 westbound traffic.


The main works contract is currently expected to be in place for 13 months (July 2017 to August 2018). 


The scheme cost of £7.1m is funded via the Local Growth Fund, which is administered by the Swindon and Wiltshire Local Enterprise Partnership (SWLEP).

These further dualling works funded through the Local Growth Fund, will complement the first two phases of dualling works that have been undertaken during 2014 and 2015. Both of these schemes were designed to address issues at specific locations, within the funding available at the time, and have been jointly funded by Wiltshire Council and devolved funding streams.


A policy of selective improvements to the A350 has been included in the council’s development plans, including the current Wiltshire Core Strategy for a number of years. These have been subject to extensive public consultation.

Given the above and the fact than no planning permission is required for the scheme, no formal public consultation has been undertaken.

The full business case is available from the Swindon and Wiltshire Local Enterprise Partnership.


The congestion and safety issues which the schemes are designed to address are a reality now and will worsen with increasing traffic and economic and development growth.

Jointly procuring and delivering the schemes provides efficiencies and better value for money.

Appropriate and safe traffic management measures will be set up to reduce the impact of scheme construction as much as possible. Inevitably, however, there will be some disruption to traffic especially at peak times. Close

The council has improved the A350 Chippenham bypass as and when funding has become available. Often this means that we have to bid for limited funding to deliver schemes in a prescribed time frame.

Funding for the latest schemes is a result of a successful bid to the Government’s Local Growth Fund (as announced in July 2014) which is administered by the SWLEP.

A further funding bid for dualling between Chequers roundabout and Lackham roundabout was submitted in July 2016 as part of a third round of Local Growth Deals. Unfortunately, the bid was not successful in achieving an allocation.

Dualling the section between the Bumpers Farm roundabout and Cepen Park South roundabout has not been progressed at this time due to funding and value for money considerations.


Current Noise levels were measured and future Noise levels forecast as part of the feasibility study. Were predicted noise levels found to be excessive, the scheme would be unlikely to receive DfT funding, or design measures would have been imposed as a condition of funding. This was not deemed to be an issue and so no special measures have been implemented.

There will be a concrete safety barrier separating the proposed northbound and southbound carriageways. This is expected to limit the noise to which local residents are subjected to no more than that currently experienced

Furthermore, a Hot Rolled Asphalt (HRA) surface course with a high stone content has been specified. High stone content surfaces provide quieter running surfaces than traditional HRA surfaces with coated chippings.

Normal practice would be to monitor the operation of a new road for a period of time before considering whether any modifications are needed to aid the flow of traffic. In the case of Bumpers roundabout, we are currently reviewing the operation of this junction with a view to making some further modifications to aid the safe flow of traffic. Should any issues arise with the operation of the other junctions, once the new works are constructed, a similar study may be undertaken.

The posted speed limit is a national limit, which is currently 60mph. Once the new road works have been completed and in operation for a few months, the need for any modifications to aid the flow of traffic may then be considered.


Outline Business Case - A350

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Outline Business Case - A350 Improvements

A350 Highway Improvements Outline Business Case

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Last updated: 16 April 2018 | Last reviewed: 16 April 2018