National Highways is warning the M4 will close completely this weekend with a warning of “substantial disruption”.

National Highways is reminding road users that the M4 north of Bristol and west of Wiltshire will be closed this weekend as part of the work on the A432 Badminton Road Bridge.

The M4 will be closed in both directions between junctions 18 and 19 from 7pm Friday 18 October to 6am Monday 21 October while a trench is dug under the motorway.

This will allow utilities to be diverted that are currently within the bridge before the structure is demolished next year.

With 3,000 to 4,000 vehicles using this section of the M4 every hour over peak weekend periods the closure is likely to cause substantial disruption, and drivers are advised, where possible, to avoid the area and plan journeys for alternative times.

For motorists, a diversion westbound will be in place:

  • From M4 junction 18, exit the motorway roundabout to the A46 heading towards Bath
  • At the A46/A420 junction just past Pennsylvania take the A420 towards Warmley
  • At the A420/A4174 junction in Warmley, take the A4174 towards the M32
  • Join the M32 at junction 1 and head to the M4 junction 19
  • Follow directions above in reverse for exiting at M4 junction 19
  • Eastbound in reverse

National Highways route manager Sean Walsh said: “This is one of the busiest sections of motorway in the South West which is why we are reminding drivers to plan their journeys during the closure

“We carefully plan our schemes to limit any inconvenience, but sometimes it's not possible to carry out the work that's needed without a closure.

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“Our message for anyone who plans to travel on the M4 around Bristol is to avoid the area if you can – if that's not possible, allow yourself plenty of extra time to complete your journey via our signed diversion routes and expect delays.”

Constructed in 1966, the Badminton Road bridge is a concrete post-tensioned structure. In July 2023, a planned detailed structural investigation revealed accelerated deterioration and cracking to the southeast underside of the structure and the bridge was closed to traffic.

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Having considered the options, demolishing and replacing the existing structure has been deemed the quickest and most economical approach.

The M4 closure has been carefully planned to happen while National Highways work on the A36 Warminster Road at Limpley Stoke has been paused to allow Wiltshire Council to undertake work on the A350.

More information about the scheme can be found here.