Designed and operated as modified trains, passenger rail systems are confined to use of locomotives and fuel that freight and other railroad trains utilize. As the least modern, and least adaptable of energy users, passenger trains have made modest progress toward use of alternative fuels, while foregoing the efficiencies of long haul freight train operations. The demands of frequent stopping, acceleration and higher speeds of passenger train operation negate any of the fuel efficiencies of long haul freight trains.
Any conversion of passenger trains to electrical or other fundamentally different power sources would require the building of entirely new and separate rail systems; thus removing passenger trains and services from the rails of the nation’s existing railroad network. Diesel and other fuels typically used to power locomotives are likely to be brought under increasing regulation and restrictions by air quality and other environmental regulators.