The in Berkshire was closed westbound between J8/9 (Maidenhead) and J10 (Reading) on the afternoon of Tuesday, October 8, due to a serious collision involving a car and a motorcycle, National Highways said.
The organisation said police and ambulance crews were on the scene, adding an air ambulance also landed.
Road closures were put in place and traffic was diverted. The temporary closure prompted traffic congestion.
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