National Highways and MJ Church have started a £20m scheme on the M4 in Wiltshire, bringing M4 traffic restrictions Swindon 50 mph into effect around junctions 16 and 17 while they stabilise 600m of embankment after a landslip made the eastbound hard shoulder unsafe. Drivers on this stretch are now passing through a worksite tied to the motorway’s next phase of repairs.
The scheme centres on 600m of embankment and uses 19,500t of locally sourced stone for backfilling. National Highways says the wider build also reuses landslip material and recycled concrete from MJ Church’s crushing plant near Chippenham to rebuild verges and embankments.
Wiltshire embankment works
The present job is stabilisation first, not the bridge work that follows. National Highways and MJ Church have to secure the embankment before the next stage can begin, because the eastbound hard shoulder is already unsafe on the affected stretch.
The scale of the operation is set out in the numbers. Alongside the 19,500t of stone, the scheme is part of a larger programme that includes 25,000t of earth, all directed at the same 600m section between junctions 16 and 17.
Autumn 2027 bridge phase
Once the embankment is stable, four bridges and barrier upgrades are scheduled to follow in autumn 2027. That sequencing means the current work is the prerequisite for the later stage, rather than a separate job running in parallel.
The way the work is being handled also leaves room for scrutiny over surface water and stability on the redesigned slope. National Highways has placed the M4 landslip remediation alongside larger resurfacing and FM programmes, focusing effort on major motorway corridors rather than spreading it thinly across the network.
For drivers, the immediate reality is a long-running work zone on a key stretch of motorway between junctions 16 and 17, with the early phase focused on making the embankment safe enough for the bridge and barrier programme that follows in autumn 2027.
