The spine car is a skeletal intermodal car consisting of a central steel spine or chassis with articulated or independent platforms, designed to carry containers or trailers with minimal dead weight. Because it lacks the heavy well structure of a well car, it is lighter and less expensive, but it cannot double-stack. Spine cars are commonly used for trailer-on-flatcar (TOFC) service and for containers where clearance does not permit double-stack operations. They are often built as multi-unit articulated sets to share trucks and reduce tare weight.
One-platform skeletal car for individual trailer or container loads; flexible assignment in mixed traffic.
Five-platform articulated set sharing trucks for lightweight intermodal service where double-stack clearance is unavailable.
Spine or flatcar equipped with trailer hitches (circus ramps or end-loading) to carry over-the-road trailers directly on the car.
Spine cars serve intermodal corridors where tunnel and bridge clearances prevent double-stack operations, and they dominate trailer-on-flatcar piggyback service for over-the-road carriers using the rail network for line-haul.