Institute for Transportation

About the research

For years, traffic engineers and planners have performed safety analyses in support of the four E’s (Education of the community, Empowerment of the members of the community, Engineering when physical modifications are needed, and Enforcement when necessary). These analyses have been done without the advantages of graphical display of information, which can often bring out patterns not easily identifiable in nonspatial data structures. Today, with the advent of low-cost and powerful desktop computing and geographic information system software, it is possible to integrate highway safety data and spatial graphics. This project created GIS-ALAS (Accident Location and Analysis System). The system provides spatial display, query, and analysis capabilities for users in highway safety, law enforcement, and health services.

In phase 1, this project converted the Iowa DOT’s crash location and analysis system (which analyzes some 700,000 crash records for the state’s 100,000+ mile roadway system) and allowed seamless migration of DOT legacy crash record systems into a state-of-the-art GIS platform, providing engineers and analysts with a powerful, yet familiar spatial-relational processing system. GIS-ALAS reproduces most of the query and reporting functions of PC-ALAS in a graphical environment which facilitates advanced spatial query and display capabilities. Customized data requests are available, and GIS-ALAS provides graphical data access, enabling the user to view and select desired locations on the network, eliminating the need for node tables and paper maps. Query results can be displayed in both map and tabular form, thereby creating more easily interpreted query results and promoting the analysis of accident patterns and causal relationships.

The project documented a literature review and a description of the state of the art and practice. GIS-ALAS, in both its Explorer ALAS and ArcView ALAS forms, were developed and documented, including the selection of the software platforms, the characteristics of Explorer ALAS, the characteristics of ArcView ALAS, distribution procedures, and database development. An update was provided on technology transfer activities, including beta testing and training.

The system was designed with local and state agency input, enabling these agencies and the research community to conduct regional and site-specific analyses of crash, driver, injury and road-related features. The system allows local law enforcement and engineers to use comprehensive state or up-to-date local data to identify and mitigate highway safety problems. Phase II efforts then focused on the refinement and enhancement of GIS-ALAS in both ESRI Explorer and ArcView, and on the use of GIS-ALAS in specific applications. The project report documents several Phase II activities including changes in the data conversion processes, a specific case study, and several technology transfer efforts. Phase III transitioned the software into a production environment at the Iowa DOT. Additional Tasks included development of an MS Access interface, inclusion of ERIS (Emergency Response Information System) data, and Location Tool and Safety System Analysis/Documentation.