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In this paper a recursive version of a dynamic road investment problem is developed by extending the Ellet-Walters developmental model of transportation so as to account explicitly for the effects of road investment on the supply and demand of the port hinterland's product. An explicit lagged supply function that depends upon commodity price and road penetration is related to a given linear demand function, assuming annual market clearance. A recursive formulation of a cobweb-like dynamic market is thus obtained. Secondly, we derive the optimal roadpenetration policy of a road-planning authority faced with a given cost function and with this form of market dynamics. The road-building policy is constrained both by long-run goals and by short-run market fluctuations so that there are no short-run disbenefits from development. We show that these constraints hold for the general case of downward-sloping demand functions and price and of road-sensitive supplies. The results are then extended to cases where farmers have differing views of future transport availability, indicating the importance of people's perception of development. The paper ends by considering the conditions under which development does not take place. The results imply that an appropriate range of technological change occurs, and that it is related to the existing level of development and the inherent stability of the market.

A Multicommodity Multimodal Network Design (MCMND) model is presented; the model is to be used as a planning tool for determining investment priorities for freight intercity networks. The MCMND model is designed to select the best set of investment options for a multimodal regional network, given a limited investment budget. The main component of the model comprises the solution of a nonlinear bilevel network design problem formulated to choose investments that minimize both the transportation costs incurred by users and the environmental impacts of less efficient modes of transportation. Investment options to be considered by the model involve the addition of new physical links to the network, the improvement of existing links, and the location of intermodal transfer facilities at specified nodes of the network. The representation of the multimodal network is at a level of detail appropriate for strategic planning for a large region. The demand for transportation services is fixed and exogenous to the model. Mode choice in shipping freight is modeled in combination with flow assignment, assuming that goods are shipped at minimum total generalized costs. A new path-based stochastic user equilibrium assignment algorithm is proposed to distribute trips over the multimodal network according to a logit-type model. The Tietê-Paraná Valley in Brazil was selected for the development of a pilot application of the MCMND model to assess its efficiency when dealing with large networks. This application also served to emphasize the importance of an interface between the MCMND model and a geographic information system in solving real-life problems.

Transportation geography is the study of the spatial aspects of transportation. It includes the location, structure, environment, and development of networks as well as the analysis and explanation of the interaction or movement of goods and people (Black 1989). In addition it encompasses the role and impacts—both spatial and aspatial—of transport in a broad sense including facilities, institutions, policies and operations in domestic and international contexts. It also provides an explicitly spatial perspective, or point of view, within the interdisciplinary study of transportation. There has been substantial progress in the development of the transportation geography subfield over the last ten years. In 1993, the Journal of Transport Geography was started in the UK, providing the subfield with its own eponymous journal. Several second editions of key textbooks were published, including The Geography of Transportation (Taaffe et al. 1996), The Geography of Urban Transportation (Hanson 1995), and Modern Transport Geography (Hoyle and Knowles 1998). The Transportation Geography Specialty Group (TGSG) instituted the Edward L. Ullman Award for scholarly contributions to the subfield; recipients have included Edward Taaffe, Harold Mayer, Howard Gauthier, William Garrison, William Black, James Vance, Susan Hanson, Morton O’Kelly, Bruce Ralston, Donald Janelle, Thomas Leinbach, Brian Slack, and Kingsley Haynes. The specialty group also began honoring students who have written the best doctoral dissertations and masters theses each year, and a TGSG web page was created. The University of Washington Department of Geography instituted the Douglas K. Fleming lecture series in transportation geography at AAG annual meetings. Finally, transport geographers have played prominent roles in a Geography and Regional Science Program organized joint National Science Foundation/European Science Foundation initiative on Social Change and Sustainable Transport (SCAST) (Leinbach and Smith 1997; Button and Nijkamp 1997). This initiative led to the development of the North American-based Sustainable Transportation Analysis and Research (STAR) network led by geographer William Black as a counterpart to the European-based Sustainable Transport in Europe and Links and Liaisons with America (STELLA) network. Together, these initiatives and research networks offer significant opportunities for geographers to contribute to a growing body of literature on the environmental, economic, and equity implications of transportation systems.

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