CM3 Trackmobile near Wasilla. (Fall 1999)
Photo courtesy of Louis Friend

A trackmobile is a vehicle with a bi-modal transport system providing an efficient and economical means of switching railcars within industrial plants and railroad terminals.
All Trackmobile vehicle models utilize two unique features that make them much more efficient and economical than conventional switching locomotives. First, a bi-modal wheel system in which steel wheels are used in the rail-working mode and rubber tired wheels are used to facilitate movement of the vehicle over roadway to new rail-working locations. And second, special couplers which transfer weight from the railcar to the Trackmobile, thus providing a tractive effort equal to much larger conventional switching locomotives.