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Wiltshire Council seeks feedback on plans to improve Junction 17 of the M4 near Chippenham

Wiltshire Council is asking for people's views on proposals to improve Junction 17 of the M4 near Chippenham.

Published 20 June 2022
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Wiltshire Council is asking for people's views on proposals to improve Junction 17 of the M4 near Chippenham.

The junction, which links the motorway network and the A350, A429 and B4122, was last modified in 2018, when traffic signals were installed on the slip roads to help prevent vehicles queueing back on to the motorway and causing safety issues. However, further improvements are required to improve safety at the junction and accommodate future traffic growth.

The proposed scheme, which is expected to cost around £27m, includes installing further traffic signals on the roundabout; widening the approaches to the stop lines at the signals to increase the number of traffic lanes and enhance traffic capacity; and increasing the number of traffic lanes on the bridges from two to three.

The council is currently preparing an Outline Business Case (OBC) for the scheme. Once complete, the OBC will be taken to the Department for Transport, which will decide whether to fund the scheme.

Cllr Dr Mark McClelland, Cabinet Member for Transport, said: This important junction connects the towns in west Wiltshire, including Chippenham, Melksham and Trowbridge with the motorway network via the A350, and also provides a link to Malmesbury and the A429 to the north.

If approved, this scheme would reduce delays, particularly during peak periods when long queues can form, increase capacity and improve safety, and also help to future-proof the junction to accommodate future traffic growth. It also meets our business plan objective of having well connected communities, and our pledge to improve this junction.

Of course, we are working closely with National Highways on this, as it is responsible for the motorway and slip roads, while we are responsible for the junction and roundabout above it.

I'd urge any interested local residents and businesses to contact our Major Highways Projects team with any comments they may have, as this will help to inform the Outline Business Case that we'll take to the Department for Transport.

If the scheme is approved, construction would start in 2024 and the scheme would be completed in 2026.

To comment on the proposals, people should email (opens new window) or write to: Major Highway Projects, Wiltshire Council, Trowbridge, Wiltshire BA14 8JN.

To find out more about the scheme, people should go to

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