With the completion of the Interstate highway system the transportation planning focus has changed. Fiscal constraints preclude system expansion at the pace needed to support continued robust economic growth. Therefore, attention in the public sector has shifted to getting more productivity out of the existing modal infrastructure through improvements in system operation and management. This shift from capital construction to asset management is also motivated by increased emphasis at all governmental levels on minimizing the adverse environmental and societal effects of transportation activities. In concert with these public sector forces has been the emergence of a vibrant and highly competitive global marketplace. International trade and transportation agreements have opened the door to continued explosive growth in global commerce. The successful global enterprises are characterized by efficient logistics involving just-in-time inventory systems and a strong emphasis on customer service. The transport demands of international corporations are forcing transportation service providers to be more efficient and responsive. The combined effect of these public and private sector forces is a sea change in the way the transportation system is planned, designed, and deployed. A major element of this transportation paradigm shift involves a view of the modal systems as components of a single, integrated transportation system where each mode plays a role based on its inherent strengths. This view motivates a search for technical and institutional improvements to enhance the "seamless" flow of goods and people between the modes. In this emerging intermodal era, there will be increasing opportunities for the public and private sectors to make worthwhile investments in intermodal facilities and technology. It follows, therefore, that planning attention will be focused on improving intermodal interconnectivity. Also, the public sector will be faced with important transport policy decisions, such as carrier regulation/deregulation, truck size and weight restriction changes, and continued consolidation of the major rail carriers. Planners and decision makers will need reliable data and transportation systems analysis tools to evaluate intermodal project and policy alternatives. Within this overall global transportation system context, this report focuses on the freight transportation planning for a major corridor. The Interstate 81 corridor is a case in point. I-81 runs from upstate New York to Tennessee through Pennsylvania, the Maryland and West Virginia panhandles and Virginia and is characterized by a high level of truck travel over much of the corridor. In spite of this corridor focus, several of the conclusions drawn in this report are relevant for freight transportation planning in general