The incident occurred shortly before 8:45am this morning. Thames Valley Police, Fire, Ambulance Services and National Highways Traffic Officers are on scene.
There is approx. 2.5 miles of congestion in both directions, on approach to the closure points. Please add an extra 45 minutes onto your current journey time if travelling on the M4.
Road users travelling westbound are advised to follow the hollow square diversion symbol on road signs:
Exit M4 at J11 and take the 3rd exit on to the A33
Turn left on to the A4
Continue following the A4 and rejoin at J12
Road users travelling eastbound are advised to follow the hollow circle diversion symbol on road signs:
Following the above route, but in reverse