I guess the best example would be our competition in Australia, where they have what's called an above-rail and below-rail freight regime. Having more than one carrier operate on rail lines is something that's done throughout the world.
Just a month ago I was in Poland visiting our customers in eastern Europe. Certainly in Poland they have such a regime. I believe they have as many as five carriers on the rail network there. How it would work, I would say, would be pretty similar to air traffic, with one centralized rail traffic control and many carriers.