Travelers usually have a choice among several transportation alternatives, most prominent being automobile, bus, airplane and railway. Rail was the preferred means of travel in the mid-nineteenth century and continuing until the 1920s, but began to decline afterward because it could not compete with the greater mobility of the automobile and the greater speed of air travel. Despite this decline, rail passenger service may yet find a new role where its potential to be more fuel-flexible, environmentally friendly, and energy efficient can be realized. Moreover it has the flexibility to avoid the congestion delays of air and roadway traffic that is likely to only worsen.

About 60 percent of transport energy in the United States is used for passenger transport, almost entirely by autos, light trucks and aviation. In fact, rail passenger services in the U.S. carry only about 2 percent of total passenger-kilometers (a...