The potential of geographic information system (gis) technology in transporation has been recognized for some time. However, only recently has gis technology been adapted to meet the requirements of transportation systems. The results presented are based on research being conducted by the caliper corporation on integrating gis technology and transportation models. First, the data requirements of various transportation models are explored. The data requirements includesequential text files for both inputs and outputs, tables containing vectors and matrices, and connected networks of nodes and links with their associated attributes. The data requirements, in turn, makea variety of demands on the structure of the gis data bases and theway the model interfaces with the gis. Next, the content and structure of a transportation organization's data bases are discussed and compared with the requirements imposed by the various model types. The traditional gis formulation is specified, and its limitations fortransportation analysis discussed. The concept of a transportation gis is developed. Research has shown that rather than a mere addition of features to the existing gis formulation, a transportation gis requires a hybrid architecture that incorporates important transportation data structures and specialized procedural input, processing, and output modules. This new formulation makes it possible to optimize both the gis functionality and the transportation and operations research modeling needs. The introduction of these transportation objects facilitates nearly all transportation applications of gis and greatly increases ease of use by transportation professionals. Finally, operational experience with caliper corporation's gis for transportation, transcad, is reviewed. This paper appears in transportation research record no. 1271, Transportation data and information systems: current applications and needs 1990.
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