AAR (Association of American Railroads) outlines the intermodal journey starting at the manufacturing facility where the intermodal container, which is affixed to an intermodal chassis, is loaded with a shipper’s freight then driven to the origin railroad ramp via a dray motor carrier. Once the container arrives at the intermodal ramp it is lifted off the chassis and placed onto a wellcar. The train cars then moves the intermodal container across the railroad network for the largest portion (in miles) of the shipment. Upon arrival at the destination intermodal ramp, the container is then transferred to a chassis for a truck to get under it and deliver the freight to its final destination.
There are two types of intermodal: Container-On-Flatcar (COFC) or Trailer-On-Flatcar (TOFC). Under the TOFC model, the over-the-road (OTR) trailer is placed directly onto the wellcar versus an intermodal container. COFC, which came to prominence in 1984, is more cost effective because four containers can be loaded onto a wellcar versus only two trailers can be loaded.