Writing specifications for bids, picking a vendor and waiting for delivery takes years, even if the money is in hand.

Amtrak is an alternative to airlines along the Boston-New York-Washington corridor, and on some routes out of Chicago and a few in California. But most of its other routes are so slow that people take those trains because they have no alternative to reach places like Burlington, N.C., or Burlington, Iowa. Or they go for the train ride itself.

The railroad carried about 25 million passengers last year and may hit 27 million this year. (That is all intercity traffic; commuter rail, connecting suburbs and cities, is also growing, but that is not Amtrak’s market.) By contrast, the airlines carry about 680 million domestic passengers a year. If Amtrak were an airline, in terms of passenger boardings it would rank approximately eighth, behind Continental and US Airways and ahead of AirTran and JetBlue.

H. Glenn Scammel, a former head of staff of the rail subcommittee of the House Transportation and Infrastructure Committee, said the railroad should give up on some of its cross-country trains and redeploy the equipment on relatively short intercity trips, where it could provide enough frequency to attract new business. (Providing one train a day in each direction will not draw many new business travelers.)

But the railroad’s labor contracts provide stiff penalties for dropping routes, and dropping states from its itinerary would hurt its political support, especially in the Senate, where thinly populated states are overrepresented relative to their population.

Image Passengers hurrying to board an Amtrak train at Union Station in Washington. Credit... Daniel Rosenbaum for The New York Times

Scarcity is not all bad for the railroad, though. It has raised ticket prices, so that it recorded ticket revenues of $153.4 million in May, up 15.6 percent from $132.7 million in May 2006. That jump is higher than the ridership increase of 12.3 percent, to 2.58 million, from 2.30 million.