Abstract: A system for moving freight carriers including highway semi-trailers and receptacles such as demountable containers and merchandise racks in trains on railway tracks includes railway trucks, each slidably mounting a transversely centered fifth wheel support to permit its positioning at different locations longitudinally of the truck and swivelly mounting a pair of longitudinally disposed structures each including a pair of transversely spaced treadways for supporting semi-trailer highway wheels such that the highway wheels at the rear of one semi-trailer can be supported on one wheel supporting structure and the fifth wheel support can be positioned between the treadways of the other wheel supporting structure to support the front end of another semi-trailer, whereby a plurality of semi-trailer and railway trucks are linkable into a train with the front end of the leading semi-trailer supported on the fifth wheel support of a road-rail tractor.