A/C locomotives in North American service: a benefits assessment

The rebirth of the US railroad industry following deregulation has produced innovation in locomotive manufacturing. Both GE and EMD have announced several new models since 1992, and an entirely new manufacturer (MX Rail) has entered the market. All three builders are promising large increases in horsepower and the use of AC traction. However, the benefits of these innovations are unclear. "Unit reduction", the substitution of fewer locomotives on a train, is only economic if the new limits cost less in total than those they replace. The AC limits are expensive. Maintenance costs should be the same or less on a per-unit basis, but the long-term maintenance cost of AC traction locomotives is unknown. The conclusion of this paper is that the benefits of AC traction and higher horsepower are uncertain at best, and remain to be proven. However, it is also concluded that the new limits unquestionably perform better than the ones they will replace, and therefore will probably be purchased even in the absence of a demonstrated economic advantage, simply because railroads need new power to handle record traffic levels.>