Here's some cheery news for travelers sick of bad airline service and fares and frustrated with the intolerably heavy interstate highway traffic during business hours: A new study says that high-speed rail passenger service between Washington and Charlotte would not only move people fast, it would also bring in more revenue than it takes to run the trains.

Of course, this is just a study of the potential for high-speed southeastern corridor rail service that would not be in operation for years. But it is a credible effort at gauging the market for rail travel and its impact on other modes of transportation.

The Southeast High Speed Rail Corridor project would link the cities of Washington, Richmond, Raleigh, Charlotte, Greenville and Spartanburg to Atlanta and Macon. Another phase of the project would also link high speed service to Columbia, Savannah and Jacksonville.

The study pegs the cost of creating the system at about $2.9 billion. The cost of the initial phase between Washington and Richmond, where work is now under way, is $370 million.

The states of North Carolina and Virginia are cooperating on the system, which has considerable business support. Now in its exploratory phase, the project recently completed a preliminary environmental impact statement. It concludes that the route could:

Triple the ridership from Washington to Charlotte by the year 2015;

Relieve the region's overcrowded highway and airline systems of 1 million auto and air trips per year;

Make the trip from Washington to Charlotte in a little more than six hours on trains that reach 110 miles per hour;

And bring in more revenue than it would cost to operate the rail system.

If all this sounds too good to be true, it's worth reflecting on the fact that the Southeast corridor from Washington to Atlanta contains some of the fastest-growing urban areas in America. And while many of the cities along the route do not have the density that Northeast cities have, the capacity of the major interstate highway routes, and of the airlines, is barely sufficient for 2001 traffic.

What, pray tell, will it be like 10 years from now? Does anyone believe entire new interstate routes, paralleling those already in existence, will handle the new traffic? Will new urban airports relieve the pressure on existing airports? Will pigs fly?