Last-minute talks to avert strikes affecting three Tube lines have failed, meaning commuters must make other plans for getting to work tomorrow and Thursday.
The Central Line and Waterloo & City Line are set to shut down for 24 hours from midnight tonight as Aslef drivers strike, with RMT drivers on that line joining the action.
Meanwhile RMT staff will strike from 1.30pm tomorrow on the Piccadilly Line until 3pm on Thursday.
TfL plans to put around 150 extra buses into service on Wednesday and over 80 extra buses on Thursday.
Both unions have cited a breakdown in industrial relations with Transport for London (TfL).
But TfL said the unions are seeking to have two drivers reinstated after safety breaches saw them sacked.
Nigel Holness, director of network operations for London Underground, said: “The strike action called by Aslef on 7 November is totally unjustifiable. The union is demanding the reinstatement of a Central Line driver sacked over a serious safety breach after deliberately opening the doors of a train in a tunnel.
“We always strive to run a reliable service for our customers but our commitment to the safety of both customers and staff is absolute and something we will never compromise on. I urge Aslef to call off this entirely unnecessary strike action which will only cause disruption to our customers.”
But Aslef organiser Finn Brennan threatened more action over the busy Christmas period if TfL did not seek to improve industrial relations.
“Unless there is a rapid change of approach from management, working inside existing agreements instead of trying to circumvent or 'reinterpret' them, then the likelihood is there will be a combine wide shutdown in the run up to Christmas.”