Well car

rdf:langString Well car

rdf:langString A well car, also known as a double-stack car (or also intermodal car/container car), is a type of railroad car specially designed to carry intermodal containers (shipping containers) used in intermodal freight transport. The "well" is a depressed section which sits close to the rails between the wheel trucks of the car, allowing a container to be carried lower than on a traditional flatcar. This makes it possible to carry a stack of two containers per unit on railway lines (double-stack rail transport) wherever the structure gauge assures sufficient clearance. The top container is secured to the bottom container either by a bulkhead built into the car (e.g., bottom and top containers are the same dimensions of 40 ft.), or through the use of inter-box connectors (IBC). Four IBCs are needed per wellcar. In the process of an inbound train becoming an outbound train, there are four processes: unlock to unload the top container of inbound train, remove then unload bottom container, insert after loading bottom container of outbound train, lock after top container loaded. Advantages to using well cars include increased stability due to the lower center of gravity of the load, lower tare weight, and in the case of articulated units, reduced slack action. Well cars are most common in North America and Australia where intermodal traffic is heavy and electrification is less widespread; thus overhead clearances are typically more manageable. In India double stacking of containers is done on flatcars under 7.45 m (24 ft 5+1⁄4 in) high catenary because the wider 5 ft 6 in (1,676 mm) gauge permits more height while keeping the centre of gravity still low.