LONDON -- Millions of commuters cycled, trudged and waited in snaking bus queues Monday as a strike by London Underground station staff shut down much of the city’s subway network.

Scores of Tube stations and many of the city’s subway lines were closed during the morning rush hour, forcing Londoners to walk, use overcrowded buses, seek scarce taxis or work from home.

Some took to bicycles, weaving through slow-moving traffic.

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“It is really scary out there, cyclists are taking huge chances,” doctor Simon Quantrill said. “The traffic is mad.”

The strike also closed subway links from Terminals 4 and 5 at London Heathrow airport and connections at London’s major train stations.

The 24-hour strike began Sunday evening, and service isn’t expected to get back to normal until Tuesday morning.

Transport unions are protesting job cuts and ticket-office closures, citing safety issues.

While acknowledging some issues needed to be addressed on the network, London Mayor Sadiq Khan described the strike as a “completely unnecessary” action that was causing inconvenience across the city.

“Why strike?” Khan told the BBC. “Why not resolve these things amicably?”

London’s subway system handles more than 4 million journeys during a typical business day.