National Highways is starting M4 motorway embankment stabilization Wiltshire work after a landslide made the hard shoulder unusable eastbound to Swindon. The repair covers 600 metres of earth alongside the route and begins with traffic management on the westbound side.
Overnight closures westbound from 20:00 GMT to 06:00 GMT will be put in place on 12 and 13 November, while two lanes will run under 50mph speed restrictions until 17 February. HGVs will be diverted via Cirencester and Malmesbury, giving drivers a set diversion pattern before the main earthworks begin.
Chris Hilldrup on the repairs
Chris Hilldrup, who handles routes for National Highways, said the £20m investment was a “significant engineering undertaking” to “maintain the safety and reliability” of the busy route. He said the first phase will only add an extra two minutes to people’s journey times.
Contractors MJ Church are set to move about 25,000 tonnes of earth before back filling with 19,500 tonnes of stone from a nearby quarry to restore the embankment and hard shoulder. National Highways says the repair work sits within a larger bridge refurbishment scheme between Junction 16 for Swindon West, Royal Wootton Bassett and Junction 17 for Chippenham.
Bridge work after 2027
Once the embankment has been repaired, National Highways said it will begin work in autumn 2027 to restore four motorway bridges. Those bridges carry the M4 over two roads at Brinkworth and Grittenham, the Swindon to Bristol railway line and a farm access road.
Hilldrup 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.”
Train services will be unaffected by the bridge repairs, but the immediate change for drivers is the mix of closures, a lower speed limit and westbound HGV diversions while the embankment is stabilised. National Highways is asking traffic to be managed around the repair phase first, then the wider bridge programme later.
