Crime & Safety
M40: ‘Overturned vehicle’ closes motorway at Oxfordshire border
The incident occurred after 10am this morning (Friday, March 20) between Junction 4 at High Wycombe and Junction 3 at Loudwater.
At the time, National Highways stated all three southbound lanes had been closed due to an “overturned vehicle”.
Royal Berkshire Fire and Rescue Service was attending the scene as queues of traffic built throughout the morning.
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The #M40 southbound between J4 #HighWycombe and J3 #Loudwater is now closed due to an overturned vehicle.@RBFRSofficial are working on scene.
More information to follow. pic.twitter.com/WgoaAPTx6d
— National Highways: East (@HighwaysEAST) March 20, 2026
Drivers were left asking for answers on social media as to when the congestion would free up, as cars were left at a standstill.
National Highways then confirmed just after 11am that the motorway’s lanes had reopened with traffic returning to normal.
A statement said: “The M40 southbound between J4 High Wycombe and J3 Loudwater is now open following an overturned vehicle.
“Thank you for your patience.”