A multi-unit rail car in which adjacent car sections share a common truck rather than each section having its own full set of trucks. Articulation reduces the number of trucks, lowers tare weight, and improves ride quality. Well-car sets and some intermodal platforms are commonly articulated in five- or six-unit sets.
An intermodal flatcar with a depressed center section (the well) that allows stacking two 20- or 40-foot containers vertically, known as double-stack operation. Double-stacking roughly doubles the payload per train and reduces cost per container. Well cars are typically articulated in sets of five or more to reduce weight and the number of inter-car connections.
The wheeled undercarriage assembly beneath a railcar consisting of two axles, four wheels, the frame, springs, and brake components. Railcar trucks allow the car body to pivot over curves and absorb track irregularities. Truck maintenance is a major source of bad-order repairs.
A high-priority train carrying intermodal containers or trailers on flatcars, typically operating on expedited schedules to compete with long-haul trucking. Intermodal trains generally run at higher speeds and have priority over manifest trains in most railroad operating plans. They serve as the interface between the rail and trucking networks.