"People say New Yorkers can't get along. Not true. I saw two New Yorkers, complete strangers, sharing a cab. One guy took the radio, the other guy took the tyres..."

David Letterman's celebrated assessment of New York was up-ended today as seven million commuters were forced to share cars, cabs and sidewalks when the city that never walks was forced onto its feet by a public transport strike.

From 3am (0800GMT), 33,700 members of the transport union staged industrial action for the first time in 25 years, crippling train and bus services. Subways were shuttered and turnstiles locked as, line by line, the entire network - whose track covers 721 miles - was closed down.

At one subway booth, a handwritten sign read: "Strike in Effect. Station Closed. Happy Holidays!"

Three hours later, bridges, tunnels and main roads into Manhattan were gridlocked: police set up checkpoints to ensure that all citybound vehicles were carrying at least three passengers.

Drivers desperate to fill their cars invited strangers to hop in, while pedestrians made for Shea Stadium where city authorities had organised a makeshift carpool centre. Cyclists streamed over bridges on rusty bikes.

As the wind chill brought temperatures down to -12C (10F), thousands more struggled in to work on foot. The Red Cross set up trucks at busy intersections, handing out cups of warming coffee and cocoa.

Michael Bloomberg, the mayor, who had said that the strike would cost $400 million a day, joined the throngs of people traipsing angrily across Brooklyn Bridge on his way in to City Hall.

He predicted "gridlock that will tie the record for all gridlocks" and said that court action would be taken to force the employees back to work. He branded the strikes "illegal and morally reprehensible" and a "cowardly attempt" by the union to gain leverage.

The dispute centres on a row over raising the pensionable age of future employees from 55 to 62. Under state law, strike action by public employees is illegal and carries a penalty of two days' pay for each day on strike, but the union has voted to risk the fines to continue its fight with the Metropolitan Transportation Assocation (MTA) after talks broke down late last night.

Although the workers' plight has previously enjoyed wide public support, there was little sympathy in evidence on the freezing streets this morning.

"I think they all should get fired," said Eddie Goncalves, a doorman trying to get home after his overnight shift.

"They should all go to jail," said Jim Giannella, 53, standing outside a Times Square station closed off with red tape."

Taxi drivers switched off the meters to charge a $10 flat rate as commuters piled into their cabs. "They are pulling the doors open left and right," said one cabbie.

"They have broken the trust of the people of New York," said Governor George Pataki. "They have not only endangered our city and state’s economy, but they are also recklessly endangering the health and safety of each and every New Yorker."

Roger Toussaint, the president of the union, defended the action. He said: "Transit workers are tired of being underappreciated and disrespected."

Tom Kelly, an MTA spokesman, said that the agency's latest offer - which included annual pay increases of around 3.5 percent on top of the average $47,000 salary (£27,000) - was fair.

Many Wall Street firms provided shuttle buses to bring workers in and financial markets were operating as normal.

"It didn’t really affect me, but it’s obviously crippled the city," said Peter Lobravico, head of merger arbitrage trading at brokerage at Access, who shared a cab with three others. "At least the cabbies are making out well," he said.

Attorneys for the MTA and the city were expected in court later today to seek a contempt ruling against the union. The last transit strike, in 1980, lasted for 11 days, raising fears of continuing chaos over Christmas.

"This could drag on for some time," said one weary worker.

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