A crash on the M25 caused a 10-mile tailback during morning rush hour on Tuesday as drivers suffered delays of over an hour.
Two of four lines on the motorway were closed clockwise between Junction 11 and Junction 12, with traffic queueing from Cobham Services to the approach to Heathrow.
It comes as major disruption to Great Northern and Thameslink trains due caused by a broken rail ended.
The broken rail at Hatfield in Hertfordshire brought chaos to services running between Finsbury Park and Stevenage throughout Monday.
In an update shortly before 7am on Tuesday, National Rail said the disruption had ended.
Meanwhile TfL was reporting a good service on all Tube lines except the Hammersmith & City, which was suffering minor delays due to a shortage of trains.
