A fault with a level crossing between Chiswick and Kew Bridge is causing delays to trains in the area.
South West Trains has warned passengers to expect delays of up to 15 minutes and revisions to some services.
The operator says trains are running at a reduced speed on all lines between the two stations as a safety precaution.
It has apologised for the disruption, which it expects to continue until 4pm on Monday (July 11).
South West Trains tickets are being accepted on London Overground services from Richmond, as well as on Transport for London (TfL) buses from stations between Hounslow and Barnes Bridge.
Southern Railway passengers have planned a protest at Victoria station on Monday (July 11) at 5.30pm against ongoing disruption which has led to the introduction of a reduced "crisis" timetable.
SWT recently completed the roll-out of 108 extra carriages , which it said would accommodate an extra 23,000 passengers on peak hour services.
