Millions of commuters faced a second day of travel chaos on Thursday due to a 48-hour strike by London Underground workers angry over ticket office closures and job cuts, with no sign of an end to the standoff between unions and rail bosses.

Staff from the two main rail unions began the first of two planned 48-hour "tube" strikes late on Tuesday, reducing the city's vital Underground network used by three million people daily to a skeleton service.

The strike has left many people unable to get to work while others joined long queues to squeeze onto crowded buses and overground trains, turned to river boat services, or resorted to running or cycling to work.

"The train was so crammed I couldn't even breathe but I do sympathise in some ways because it's their jobs," said Omar Salahuddin, 29, a teacher, whose journey from Pinner in northwest London to Canada Water in east London took four hours instead of the usual one hour.

But the lengthy, and sometimes costly, alternative routes to work on Wednesday appeared to have deterred more commuters from battling the transport chaos on Thursday.

"#tubestrike day 2 = half empty tube pulls up as I get to the dead platform. Is everyone working from home today?!" tweeted Daniel Mryan.

The unions are protesting about plans to cut about 950 jobs and close manned ticket offices as part of a restructuring that Transport for London (TfL), which runs the capital's public transport network, says could save 50 million pounds ($80 million) a year.

Bob Crow, general secretary of the Rail, Maritime and Transport workers (RMT) union, one of Britain's most militant, said the action was as much about service as jobs, warning that TfL's plans to reduce station staff would have a "seriously adverse impact on women, older and disabled people".

Talks between TfL, the RMT and the Transport Salaried Staffs' Association (TSSA) union are due to resume on Friday in a bid to avert a second 48-hour walk-out planned from Feb. 11.

But talks at an arbitration service last week and early this week have so far failed to find any common ground.

During rush hour on Thursday morning, TfL said just one underground line was running normally with the remaining 10 either closed or operating a reduced service.

TfL said commuters had found alternative ways around town on Wednesday with a 50 percent increase in the use of its city cycle hire scheme, known by Londoners as "Boris bikes" after mayor Boris Johnson.

Business groups have condemned the strike, with the London Chamber of Commerce and Industry estimating the action would cost the city's economy 50 million pounds a day.

Prime Minister David Cameron has called the stoppage "shameful" and says there is no justification for it because a modernized tube service is critical for Londoners.

Political analysts have said Cameron, leader of the Conservative-led coalition government, could gain politically from the strike if travellers blame the unions, which have close links to the centre-left opposition Labour party.

His office has said the Conservative manifesto for next year's general election is likely to contain proposals to curb unions' ability to call strikes in key transport areas. -Reuters