Commuters stranded from Virginia to Massachusetts. Train service shut down at major terminals in New York, Chicago and Boston. A flood of extra cars on congested highways around Washington and San Francisco.

Come Jan. 30, that nightmare could become a reality unless a long-standing labor dispute between Amtrak and nine unions is resolved.

There has never been a strike in Amtrak's 36-year history, and it's still likely that one will be averted, either through a last-minute deal or intervention by Congress.

But if workers do walk out, the 71,000 people who take Amtrak every day won't be the only ones who'll suffer. Hundreds of thousands of people who ride commuter trains will join them, since many such services depend on Amtrak employees or infrastructure, particularly in the Northeast.

The dispute involves about 10,000 employees whose last contract ended Dec. 31, 1999. After years of unsuccessful mediation, a presidential emergency board issued a report on the dispute Dec. 30, triggering a 30-day countdown until a strike becomes legal.

Siding with the unions, the board recommended that wage increases be made retroactive. Amtrak, which relies on federal subsidies, is worried about whether it can afford the back pay.

Under the Railway Labor Act, most disputes that get to this point end with a contract based on the emergency board's report. In cases when that doesn't happen, Congress usually imposes the board's recommendations.

Still, transportation officials across the country are bracing for the worst.

The biggest impact of a strike would be felt around New York City, where two major services, New Jersey Transit and the Long Island Rail Road, would be disrupted.

Just over half of NJ Transit's 740 weekday trains travel for all or part of their routes on lines owned by Amtrak; if Amtrak employees aren't at work, trains can't run on those tracks. Some 218,000 daily trips are taken on the affected lines.

East of Manhattan, the vast majority — about 85,000 — of the Long Island Rail Road's morning rush-hour passengers travel to Penn Station, where Amtrak owns the tracks and handles the dispatching. Without the use of its only Manhattan terminal, the LIRR faces the prospect of thousands of extra customers overwhelming smaller stations in Queens as they get off to transfer to the subway.

Train riders will face similar problems in Chicago and Boston, where the hubs at Union Station and South Station would close.

On the West Coast, Caltrain, which uses trains staffed by Amtrak to move an average of 36,000 riders a day between San Francisco and San Jose, Calif., would be shut down.

Commuter rail operators have been scrambling to come up with backup plans. But they emphasized that any such plans would provide, at best, a partial fix.

"There is simply no way to replicate the capacity that would be lost during an Amtrak strike," NJ Transit spokesman Dan Stessel said. "The contingency plan will provide customers who absolutely must travel with the ability to do so during limited hours. It will not be a complete replacement of the service that would be lost."

At New York's Penn Station, 22-year-old student Deann Stout said a strike would mean making the more than 60-mile trip from her home in Trenton, N.J., to school in the city by car — an expensive proposition.

"Gas money, toll bridges, parking," she listed, estimating the trip would cost her at least $30 a day, more than double NJ Transit's $264 student monthly pass.

Riders on a slew of smaller services around the country also would feel the impact. The Virginia Railway Express and Connecticut's Shore Line East would grind to a halt. Maryland's MARC service would have its most popular line shut down and would have to make do without Washington's Union Station. Commuters in Philadelphia could face the loss of six rail lines.

If commuter rail is curtailed by a strike, people who typically drive would see the roads suddenly get a lot more crowded, officials warned.

The prospect of widespread misery makes rail operators hopeful that a strike won't be allowed.

"No. 1, you hope that Congress steps in," said Jawauna Greene, a spokeswoman for the Maryland Transit Administration. If it doesn't, "we'll triage to the best of our ability," she said.

Lawmakers are still pushing Amtrak and the unions to resolve the dispute on their own.

Talks between Amtrak and the unions were to resume Wednesday.