M4 junction 17 layout could be reversed ahead of overhaul

Wiltshire Council has been granted £26.087 million of Department for Transport funding to move forward with plans to increase the capacity of junction 17 of the M4.

The scheme, which is part of the Major Road Network programme, is expected to cost £31.937 million with the council providing the remaining budget.

This new project is separate from the alterations made to the junction, as part of the Chippenham Gateway Project in October last year, which have caused problems for drivers.

Under the current roundabout layout, designed to accommodate increased traffic once the newly built St Modwen development is occupied, the left-hand lane is only for those heading west on the M4.

This has regularly caused extended queues in the right-hand lane of the A350 northbound and some motorists have labelled the changes “dangerous.”

Queues on the A350 approaching the M4 junction 17 (Image: Newsquest)

Wiltshire Council previously said this layout is the most “efficient” option but has now confirmed it could be reversed in the short term.

The council is carrying out traffic modelling to persuade National Highways that returning the A350 northbound lane designations to the previous arrangement would improve “junction performance".

Cllr Nick Holder, cabinet member for highways, said: “We know there have been increased queues at junction 17 following the Chippenham Gateway Project.

“Which is why we’re working with National Highways to try to find a medium-term solution, while we work on the Full Business Case for our Major Road Network project to further develop our plans to improve the junction.”

Department for Transport funding for these plans comes after the approval of the council’s outline business case, which sets out the costs and benefits of the proposal to overhaul the busy junction.

The council will now be able to develop the full business case during which the full design of the project will take shape.

Queues on the A350 approaching the M4 junction 17 (Image: Newsquest)

Cllr Holder added: “It is fantastic news for Wiltshire that we have received approval from DfT for our outline business case.

“This is a key strategic junction which provides the vital link between the motorway network and the A350, connecting the towns in the west of the county, including Chippenham, Melksham and Trowbridge.

“It also provides a link to Malmesbury and the A429 in the north, along with local access to the B4122.

“If approved, the scheme will increase capacity at the junction to ensure it is fit to serve the county for many years to come, meeting our business plan commitment to have well-connected communities.”