A bi-modal freight trailer designed to be pulled by a semi-truck on highways and then assembled directly into a train without needing a flatcar. Each trailer has its own set of retractable rail wheels or sits on specialized intermediate bogies. They reduce weight and clearance issues compared to standard piggyback trains but require dedicated terminals to assemble.
Heard on the job
The dispatcher is holding the eastbound manifest in the siding so the hotshot RoadRailer train can pass.