ALCO RS-1

The ALCO RS-1 is a four-axle diesel-electric locomotive built by Alco-GE from 1941 and by the American Locomotive Company through 1960, with 469 units produced over nineteen years, the longest production run of any diesel locomotive sold in the North American market. It grew out of a 1940 request from the Rock Island Railroad for a versatile road switcher able to work both mainline and yard duty, and ALCO answered with a pioneering hood-unit design in place of the enclosed cab units then standard, giving crews better rear visibility for switching and letting the locomotive run in reverse without turning around. That hood-unit layout went on to shape most later North American road switcher designs.