Role of Geographic Information Systems in Regional Transportation Planning

Geographic information systems (GISs) are becoming more widely used in transportation planning agencies, especially among metropolitan transportation organizations. The extension of GIS into transportation (GIS-T) is driven largely by the requirements of the Intermodal Surface Transportation Efficiency Act of 1991 (ISTEA), the Clean Air Act Amendments of 1990, and legislation by states that mandate the development of transportation programs to reduce traffic impacts. Traditionally, transportation modeling of traffic impacts, calculation of vehicle emissions, and consideration of wider transportation planning effects, including transit, have employed different modeling techniques, often in different agencies or in separate sections within an agency. The results from these modeling and planning exercises have more often than not been displayed on different map bases, using different graphic programs to represent the data. The requirements of federal and state programs are encouraging modelers and planners to consider more consistent methods of data integration and display, hence the growing interest in GIS-T. The role of GIS-T in regional transportation planning is evaluated, including data integration issues, the configuration of transportation networks for use with GIS, and the linkage of transportation models to GIS.