A motorway was closed northbound after a multi-vehicle crash, causing seven miles of congestion.
The collision took place near junction five for the A40 at Stokenchurch in Buckinghamshire.
National Highways said traffic had been diverted off and on the motorway at junction five.
A spokesperson said the road reopened at about 19:45 BST, but warned of continued delays of about 90 minutes and five miles of traffic.
