All we know as M4 to shut and speed limits put in place

The westbound carriageway between junctions 16 and 17 in Wiltshire will be closed overnight from Tuesday, November 12, to Wednesday, November 13.

This closure will allow National Highways to install a new 50mph speed limit and set up two-lane running as part of ongoing repair work.

The project began on October 5 and is expected to continue until February.

During the overnight closure, westbound traffic will be diverted through Royal Wootton Bassett via the A3102, then onto the A4 to Chippenham, and the A350 to the junction 17 roundabout.

HGVs will follow a separate route via Cirencester and Malmesbury.

Once the closure is complete, the M4 westbound will remain reduced to two lanes under a contraflow system, with lane one and the hard shoulder closed.

The eastbound lanes will run as normal.

A 50mph speed limit will be in place from November 13 to February 17 to protect both drivers and workers.

National Highways has advised drivers to allow extra time for their journeys, particularly during peak hours, as minor delays are expected.

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Chris Hilldrup, route manager for National Highways, said: "Many of the roads and bridges we manage were built around 60 years ago and are nearing the end of their life span, so we're acting now and renewing them to prevent bigger problems further down the line.

"This £20m investment along the M4 in Wiltshire is a significant engineering undertaking.

"Once we have stabilised the embankment, we will refurbish the bridges and upgrade barriers to maintain the safety and reliability of this busy route for many years to come."

The repairs address damage caused by a landslide earlier this year, which left part of the eastbound hard shoulder between junctions 16 and 17 unusable.

Contractors MJ Church will move around 25,000 tonnes of earth, replacing it with 19,500 tonnes of stone from a nearby quarry.

This work must be finished before scheduled bridge repairs begin in autumn 2027.

The wider £20 million scheme includes refurbishing four bridges and upgrading 1.3 miles of safety barriers.

The repairs include embankment stabilisation, safety barrier upgrades, hard shoulder reconstruction, and drainage improvements.

Bridges to be upgraded include those at Brinkworth, Grittenham, the Swindon to Bristol railway line, and a farm access road.

Train services are expected to continue running as normal during the works.

National Highways has warned that closure dates and times may change at short notice.