Note: Service network as of 2012.
Inaugurated in 1986, Triple Crown (TC; a subsidiary of Norfolk Southern), was a bi-modal transport network servicing the eastern part of the United States, including southern Ontario, Canada. It uses a hybrid technology since it combines specifically designed trailers with rail bogies (called RoadRailers) to form unit trains that can be composed of up to 150 trailers. Although Triple Crown is a form of intermodalism, the term bi-modal appears more suitable in this case since the load units are not transferred from road to rail (and vice-versa) in the standard sense of a load break where intermodal equipment is required (e.g. RTGs or side-loaders). The load units (trailers) are simply assembled in rail convoys at the origin and disassembled at the destination.
From an initial service of 150 trailers between California and Chicago, the network has grown to a fleet of 7,000 trailers servicing 14 dedicated terminals and accounting for more than 700,000 movements annually in 2012. Also, about 850 drivers are used for regional drayage. The network is structured in a classic hub-and-spoke design, with Fort Wayne, Indiana, acting as the hub. Trailers are picked up from customers and brought to the nearest TC terminal, generally over a distance of fewer than 200 miles (325 km). At the terminal, trailers are assembled into convoys by being latched onto bogies to form an intermodal unit train that will be forwarded to the hub (Fort Wayne). At the hub, trailers are rearranged into convoys for their respective destinations, where trailers will be unlatched and hauled to the final customer.
One of the main advantages of this type of service is that it uses less intermodal infrastructure than a regular TOFC or COFC intermodal service. Terminals are simpler and smaller, requiring less capital investment while conferring an intermodal service over shorter distances. It thus tends to be complementary to intermodal rail services since it dominantly focuses on the domestic market. In contrast, intermodal rail tends to be more of a port gateway/hinterland access service. Drayage distances are also reduced as long-distance haulage is done by rail. Still, specifically designed trailers are required, and the service takes longer than a direct road connection.
In 2015, NS started to scale down the Triple Crown network, particularly because of shifts in the domestic demand dependent on the automotive sector. The long-term goal is to switch to a fully containerized system (domestic and ISO containers). In 2020, only one service was left, connecting Detroit and Kansas City, and by 2022, it was discontinued, marking the end of roadrailers.