LONDON » Millions of Londoners are struggling to get to work by road, rail boat and bicycle as a strike by London Underground workers shuts down much of the city’s subway system.

Thousands of maintenance workers, drivers and station staff walked off the job for 24 hours in a dispute over planned job cuts that they say will hit service and safety.

More than 3.5 million people use the subway system, known as the Tube, daily. Transport for London said Tuesday some services were operating on six of the city’s 11 subway lines.

The Rail, Maritime and Transport Union said support for the strike was strong and only a skeleton service was running.

Buses were packed, and thousands of people were expected to use extra boat services on the River Thames.

The strike is due to end Tuesday evening.