The Pennsylvania Department of Transportation is conducting a study focusing on risk assessment associated with movement of hazardous materials, and determination of corresponding vulnerable areas in the state. A goal of this research is to make the hazardous material risk assessment an integral part of accident analysis find risk management functions in transportation agencies. To achieve these objectives, the authors developed an interactive, user friendly microcomputer package. The risk assessment model behind this package relies on the notion that data can be obtained easily and updated over time. This package, therefore, employs existing data on accident reports, traffic information, and geometric parameters that is transferred from a mainframe database to the microcomputer. The modelling framework consists of several modules: LEVEL, EDIT, INFO, ZOOM, ANALYZE, MITIGATE, PRINT, HELP, RESET, and QUIT Module. It employs a color coding of streets, municipalities, counties, and states for easy and clear interpretation. To enhance graphic display capabilities of the model, shape points are digitized for each network link. In the LEVEL module three different scales are defined ranging from a small scale county level to a large scale street level, namely, 1)County, 2)Municipality, and 3)Street Any scale may be selected for analysis at any time in the procedure. All other modules are, then, performed on the basis of chosen scale. The EDIT module can be used for data input or investigating hypothetical changes in order to determine the best strategies for problem alleviation. Creating or deleting techniques are included to avoid redigitizing the whole map provided link geometries will be changed over time. Edited data can either be saved on diskette files or be used temporarily in memory without altering original flies. The INFO module employs dialogue boxes with bar graphs or color shadow maps to facilitate depicting numeric values of input and output statistics. The ZOOM module allows user to see the area in question in more detail. The ANALYZE module comprises the main part of this package. Two primary features include : 1) vulnerability and risk assessment at the macro level which provides a ranking of the most affected counties, municipalities and streets (Macro analysis), and 2) risk analysis at the micro level (i.e. street level) which determines corridors of least risk between fixed origins and destinations (Micro analysis). The MITIGATION module is provided for evaluation of mitigating measures. The HELP module uses pop-window techniques to provide quick information with minimal program disruption. The RESET module exits ZOOM module and resets screen. Finally, QUIT module shells out to DOS or exits the package. / Ph. D.