A serious collision is causing severe delays on the M4 this afternoon.
The motorway is partially blocked westbound between Junction 16 (Swindon) and Junction 17 (Chippenham); one lane is open past the scene. Lane three is also closed eastbound.
It’s understood one vehicle has crashed into the central reservation causing extensive damage. Highways England are at the scene. 
Normal traffic conditions aren’t expected until around 4pm, due to repair work.
