Spatially Generated Transportation Demands

Transportation demanders are located at different points in geographical space and have differential access to modes. Central to the planning of transportation infrastructure is the aggregation of different shippers by mode over space. We estimate a modal choice model for rail and barge. However, shippers may not have direct access to one or both modes and incur access (truck) costs. The results indicate that access costs, barge and rail rates, and shippers' attributes matter significantly in mode choice. The choice model is then augmented by rate functions defined over space and used to derive spatially generated modal demand functions.