IN a recent paper, Zimmerman [I7] has argued that developments in the electrical-utility energy markets during the 1970S should have caused a substantial increase in unit-train coal rates. With respect to the energy market in general, the constraints upon railroad coal rates that have tradi- tionally been imposed by the availability of alternative energy sources have been largely removed by the shortages in natural gas, the increase in oil prices, and the concerns with nuclear power that have developed over the past few years. With respect to the unit-train coal market, the develop- ment of the Western coalfields has provided the railroads serving those areas an opportunity to develop new pricing structures that are not depen- dent upon past practices.