The M4 eastbound in west London near Heathrow Airport was closed as police investigated an “incident” on the motorway.
National Highways (NH) had told motorists to expect delays of 20 minutes and three miles of congestion following the incident at Junction 3 earlier on Monday morning.
“Following an incident recently, road is closed within J3 for @metpoliceuk investigation work,” it wrote on X.
The motorway, a major commuter route into the capital, was closed from shortly after 6am so that the Metropolitan Police could carry out their work.
The incident was fully cleared and all lanes reopened on the motorway by 8:15am.
Elsewhere, part of the M3 was shut following a collision. The eastbound within Junction 11 near Winchester, Hampshire was shut at around 7.30am.
One lane was shut on the motorway and drivers were told to expect delays of up to 45 minutes.
All lanes of traffic have since reopened.
“Following the earlier collision, the vehicles have now been recovered and all lanes are open,” NH said in a statement.
“30 min delay remains but should begin easing now.”