The District Line is part-suspended on Tuesday afternoon due to a track fault.
No services are running between High Street Kensington and Edgware Road, says TfL.
Train cancellations are also causing minor delays between Leytonstone and Hainault via Newbury Park.
Earlier, traffic was queueing on the M25 either side of the Dartford Crossing after a vehicle stalled inside the tunnel and a crash closed lanes on the motorway.
Traffic monitor Inrix was reporting 10-mile tailback on the M25 at 10.15am on Tuesday due to the two incidents, as well as a vehicle that had stalled on the M25 anticlockwise.
The disruption had lessened by around 2pm, but there remained heavy traffic on the approach to the Dartford Tunnel.
