Intermodal freight transportation and regional accessibility in the United States

The authors investigate how the intermodal freight-transportation network affects the ability of regions to position themselves more effectively in the national space economy. The case of domestic containerized freight traffic is examined because it is closely associated with contemporary forms of integration between rail shipping and trucking. With the help of a geographic information system, the potential impact of intermodalism in the United States is analyzed by mapping integral place accessibility measures of five-digit zip-code areas. The performance of the intermodal freight network is evaluated by comparing accessibility measures based on the highway network and on the intermodal network, respectively. Geographically weighted regressions are also performed to identify the variables that contribute to the improvement of accessibility due to intermodalism, while accounting for the spatial nonstationarity of relationships.