The emergency services were called to Eastcote Road near South Harrow station shortly before 7.30am today (May 1).
The ambulance service rushed to the scene in five minutes to find a man had been injured.
He was taken to hospital where his condition is not known.
Eastcote Lane was closed in both directions with the AA reporting significant congestion and that a number of bus routes were diverted.
A London Ambulance Service spokesperson said: “We were called at 7.22am this morning (Thursday 1 May) to reports of a road traffic collision in Eastcote Lane, South Harrow.
“We sent resources to the scene, including an ambulance crew and paramedics in fast response car.
“The first of our crews arrived at the scene in five minutes.
“Our crews treated a man at the scene, before taking him to hospital.”
