London Tube started emptying out by 7pm on Monday ahead of the strike that starts at midnight on Tuesday.
The rail strikes were given the green light to go ahead after last ditch talks failed to resolve a dispute over pay, jobs and conditions, the RMT union said.
A series of strikes at Network Rail and 13 train operators will go ahead on Tuesday, Thursday and next Saturday amid an ongoing dispute over pay and pensions.
RMT and Unite workers will also stage a walk-out on the London Underground on Tuesday.
Mick Lynch, general secretary of the RMT, said unions were not looking to compromise and warned travellers that industrial action could stretch on for months.
The RMT general secretary said the union had rejected below inflation pay rises Network Rail.
A temporary timetable is being introduced with several rail operators winding down services this evening.
