TWO lanes of the M4 westbound between Junction 16 and Junction 17 were closed this lunchtime due to a multi-vehicle collision.
The accident happened just after 12pm between the junction for Swindon West/Royal Wootton Bassett and the junction for Chippenham.
Highways England are warning people to expect long delays as two of the three lanes remained closed until 1.30pm.
The vehicles involved are now on hard shoulder and debris has been cleared from carriageway.
All lanes are open.