Ealing motorists are facing queues due to a collapsed manhole in Perivale.
One lane has been closed on the A40 Western Avenue westbound between Alperton Lane and the Medway Underpass.
The lane has been closed due to a collapsed manhole on the road and police are currently on the scene, Transport for London (TfL) said.
Congestion is continuing to A406 Hanger Lane.
TfL said: "A40 Western Avenue W/B app Perivale Lane - Lane 1 (of 3) closed due to a collapsed manhole. Police on-scene."
Chris Rattus, a policeman, tweeted a picture of the manhole along and said: "Lane 1 closure A40 westbound just prior to Perivale due to collapsed manhole. Traffic slow on passing."
What is a manhole?
A manhole is a small covered opening, in a paved area, which gives access beneath to a sewer.
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