Road Switcher

A road switcher is a type of railroad locomotive used for delivering or picking up railcars outside of a railroad yard. Since the road switcher must work some distance away from a yard, it must be able to operate at road speeds, it must also have high-visibility while it is switching, and it must have the ability to run in both directions. Additionally, a road switcher must have the power rating and cooling capacity of a traditional road engine, and a road switcher must have road trucks, not switcher trucks. For these reasons, road switchers are generally hood units. The set-back cab of a hood unit provides more safety in the event of a collision at speed than most switcher designs, and the rear visibility is much better than that of a cab unit. Due to their ability to both run at road speeds and switch cars, road switchers are often used for yard duties. Some road switchers were provided with twin control stands, so that the units could operate conventionally (locomotive engineer and conductor/switchman facing the direction of travel) in either "long hood forward" or "short hood forward" directions. These twin control stands have fallen into disuse as, today, almost all operations are "short hood forward". For obvious reasons, the short hood is labeled "F" (meaning "front").

Alco's RS-1 was the first successful example of the type, and virtually all modern hood units are laid out in a similar fashion (long hood for all propulsion equipment, short hood for crew accommodations including a toilet).

Fairbanks Morse entered the road switcher field in 1947 with the H-20-44.

EMD was the last to enter the field and failed to capture much of the market with their first road switcher the BL2.

The RS-3 was the best known of the Alco RS road switchers and was produced in more numbers than the RS-1 and RS-2 designs combined.

Although Alco produced the first known road switcher, EMD's GP7 was probably the most successful model from this early period road switchers.

Although it is always controversial to generalize about "generations" of road switchers, these ubiquitous beasts of burden can be divided into: Generation 1, 1,999 horsepower (1,491 kW) or lower, net for traction; Generation 2, 2,000 horsepower (1,500 kW) to 2,999 horsepower (2,236 kW), net for traction; Generation 3, 3,000 horsepower (2,200 kW) to 3,999 horsepower (2,982 kW), net for traction; and Generation 4, 4,000 horsepower (3,000 kW) or higher, net for traction. Although at one point 6,000 horsepower (4,500 kW), net for traction, units were made, these quickly fell into disuse, and most have been scrapped by North American railroads. The most common new units made today are 4,300 horsepower (3,200 kW) to 4,400 horsepower (3,300 kW), net for traction.

Within the Americas, road switchers are almost always diesel-electric, with the "transmission" system being either direct current (standard performance units) or alternating current (high performance units). Outside the Americas, road switchers often have a "transmission" system which is mechanical or hydraulic.