In railroad terminology
is a highway trailer
, or semi-trailer
, that is specially-equipped for use in railroad intermodal
The advantage of using roadrailers is that due to their construction, the trailers can be pulled directly behind other freight (or even passenger) equipment without the use of trailer flatcars.
Roadrailers first appeared on American railroads in the 1950s. The trailers were built with integrated railroad wheelsets that could be lowered into position when the trailer was pulled behind a train. More modern roadrailers do not include integrated railroad wheels, but ride on specially-manufactured bogies that do double-duty, serving as articulation points between multiple trailers in a train. Each truck is equipped with two fifth wheels and at one end (or both ends) of a convoy there is an adaptor truck equipped with one fifth wheel and one regular AAR Type "E" or Type "F" automatic coupler. Each semi-trailer has one king pin at each end. Because the bogie is significantly lighter than a rail flatcar or well-car, roadrailer freight trains are much lighter and therefore are more energy efficient than traditional intermodal trains.
In the 1960s, a fully functioning HO-scale model RoadRailer was manufactured by British toymaker Lines Brothers
as part of their 'Minic Motorways' range. This allowed the trailer to be remotely coupled and uncoupled from a railway bogey and/or a road tractor unit. Today, Bowser makes an HO model of the current RoadRailer in kit form and the couplermate to connect the locomotive to the trailers. DeLuxe Innovations makes an N scale ready to run model of the RoadRailer trailer and CouplerMate as well.
Roadrailers have been used in:
- The American Railroad Passenger Car by John H. White, Jr. Two Volumes (1978) by Johns Hopkins University Press.
- ISBN 0-8018-2743-4 (pbk.: set: alk. paper)
- ISBN 0-8018-2722-1 (pbk.: v.1: alk. paper)
- ISBN 0-8018-2747-7 (pbk.: v.2: alk. paper)
- Daniels, Rudolph (2000). Across the Continent: North American Railroad History. Indiana University Press, Bloomington, IN. ISBN 0-253-21411-4.