The A40 in Hillingdon has re-opened after it closed when two lorries crashed near to Swakeleys Roundabout.
The collision just before 12pm on Wednesday, July 30, left a man in his 20s needing hospital treatment for a head injury.
The westbound lane of the A40 closed at Hillingdon Circus and has remained shut, causing major tailbacks and congestion on local roads around Hillingdon.
Transport for London warns that queues will take time to clear as traffic had backed up as far as Greenford.
It is the second time in a week that the A40 closed in Hillingdon, after it was shut following flash floods in the borough on Monday, July 28.
Photos sent in from a witness of the earlier crash showed the damage caused when the two lorries collided.