It's a concept that has some obvious appeal.
Europe has these factors in abundance, given its population density and relatively short distances between major cities. Even there, however, it hasn't worked out as well as many people might imagine as this Cato Institute study notes:
Rail has continued to lose importance since 2000. In the EU-25 (the 25 members in the European Union as of 2005), rail’s share of travel declined from 6.2 percent in 2000 to 5.8 percent in 2004, while air’s share increased from 7.7 to 8.0 percent and autos’ share (including motorcycles) increased from 75.5 to 76.0 percent. At best, high-speed rail has slowed the decline of rail’s importance in passenger travel.Now let's try to imagine how rail might work out here. The NYT article notes that "North Carolina, which is part of the Southeast High-Speed Rail Corridor, will seek some of the stimulus money to speed rail service between Charlotte and Washington."
...Rail’s declining importance in Europe has come about despite onerous taxes on driving and huge subsidies to rail transportation. European nations impose 300 to 400 percent taxes on motor fuel, and much of the revenue is effectively transferred to rail subsidies.
“Rail is heavily subsidized,” says University of Paris economist Rémy Prud’Homme. “Users pay about half the total cost of providing the service.” Prud’Homme estimates that rail service in the EU-15 receives about 68 billion euros—or about $100 billion—of subsidies each year.
How might this work? Well, the driving distance from Charlotte to DC is almost exactly 400 miles. We can expect that a high speed rail line would be something similar with likely stops in Greensboro, Raleigh and Richmond along the way to pick up more passengers. Assuming a generous speed of 150mph (the Acela averages 84pmh from DC to NY) and 20 minute pauses at each stop you're still looking at a trip of about 3 hours and 40 minutes.
A direct flight, meanwhile, takes about an hour and 20 minutes and of course there is more time factored in for the trip to the airport, check-in, security, etc. Even if you add another two hours, however, the time required still comes out slightly better or the same as taking the train.
Then there's cost. Booking a trip 3 weeks in advance (Mar. 13-15) gets you a flight from BWI to Charlotte for $202 on US Airways according to sidestep.com. Amtrak's website quotes such a trip using the same dates at a price of $158 on a slow moving train that would take about 8 hours. High-speed rail, it stands to reason, would cost significantly more.
It's also worth noting that you have an array of possible departure times when traveling via air but almost none when traveling with Amtrak.
Trains may seem attractive, but when subject to scrutiny just don't make a great deal of sense. Nevertheless, they certainly seem to have an ability to get people excited, which is what many politicians place a premium on: