A 24-hour strike is taking place on the Central and Waterloo & City lines on 7 November, with limited or no service across both lines.
The Central line will resume at around 5.30am on Thursday 8 November.
During the walkout, Central line tickets are being accepted on London Buses, London Overground, London DLR, TfL Rail and Greater Anglia services.
The strike has been called by the the Rail, Maritime and Transport (RMT) union, which cites a breakdown in industrial relations and abuse of procedures as the cause behind the strikes.
General secretary Mick Cash said: “Industrial relations along the Central Line have been at breaking point for some time now and the failure of the management to address the issues, and a conscious decision to up the ante by attempting to single out and pick off individual members of staff, has tipped the situation over the edge and has led to the announcement of strike action."
Separately, Heathrow Express and Transport for London trains between the airport and London Paddington are heavily disrupted because of Network Rail carrying out “urgent repairs to the track between Hayes & Harlington and London Paddington”.
It appears that there is a broken rail between Ealing Broadway and West Ealing, and while engineers are working to repair the damage trains on the other lines which would normally be travelling at over 100mph are being slowed to a crawl for safety reasons.
Passengers are being warned: “Trains may be cancelled, delayed or amended to not call at all stations.”
Long-distance services are being affected. Two trains from Swansea, Cardiff and Newport are arriving over an hour late, and the early arrival from Plymouth and Exeter has been cancelled.
Other London Underground lines are extremely busy this morning. Passengers have been sharing images of packed trains.
“Industrial relations along the Central Line have been at breaking point for some time now and the failure of the management to address the issues, and a conscious decision to up the ante by attempting to single out and pick off individual members of staff, has tipped the situation over the edge and has led to the strike action today."
It calls today's strike action the "clearest possible demonstration" to TfL bosses about "the level of anger on the job".