AASHTO’s Highway Safety Manual (HSM), published in 2010, presents a complete collection of quantitative safety analysis methods. It allows decision makers and engineers to evaluate safety alongside other transportation performance measures, such as traffic operations, environmental impacts, and construction costs.
The Illinois Department of Transportation (IDOT) sought to expand the implementation of HSM methods to boost roadway safety in Illinois. However, the highway inventory data required for this implementation are not stored in IDOT’s databases. Therefore, a research project, funded by IDOT and conducted by the Illinois Center for Transportation (ICT), was instituted to identify and comparatively evaluate cost-effective techniques and methods for collecting and storing highway inventory data.
According to Priscilla Tobias, State Safety Engineer for IDOT and its Bureau of Safety Engineering, “With increasing emphasis on performance measures and data-driven methods to understand the safety issues, select the appropriate safety strategies, and direct limited resources to reduce traffic-related fatalities and serious injuries, having better data is essential.” This research project would help IDOT advance its overall safety efforts.
Rob Robinson, Section Chief in IDOT’s Office of Planning and Programming (now retired) and Kim Kolody, Senior Highway and Traffic Safety Engineer at CH2M HILL, representing Priscilla Tobias and the Bureau of Safety Engineering, co-chaired the Technical Review Panel (TRP) that guided the research.
The costs, benefits, and logistics associated with several methods and techniques used for collecting, analyzing, storing, retrieving, and viewing highway inventory data were examined. In addition, a Web-based survey of 49 U.S. states and 7 Canadian provinces was conducted to evaluate the strengths and weaknesses of various highway inventory data collection methods with the help of different state departments of transportation.
Huaguo Zhou, associate professor in the Department of Civil Engineering at Auburn University, formerly at Southern Illinois University Edwardsville (SIUE), served as principal investigator for the study. Professor ShunFu Hu in the Department of Geography and assistant professors Jie Gong and Mark Grinter in the Department of Construction at SIUE served as co-principal investigators.
With the requirements set forth in the federal Moving Ahead for Progress in the 21st Century Act (MAP-21) for collection of data elements contained in the Model Inventory of Roadway Elements (MIRE), determining the most effective method to collect necessary data becomes critical. “This research explored various options that IDOT’s Bureau of Safety Engineering and other offices can use to collect the highway inventory data necessary for implementing the HSM. The research results present the advantages and disadvantages of each highway inventory data collection method,” says Zhou. “It is expected that decision makers will leverage the findings of this research to select the most cost-effective method.”
The data collection methods identified as most promising were field tested for further evaluation. Five collection methods (GPS data logger, robotic total station, GPS-enabled photo/video log, satellite/aerial imagery, and mobile LiDAR) were used to collect HSM-related road inventory data along four 2-mile road segments—rural two-lane highway, rural multi-lane highway, urban and suburban arterial, and freeway. In addition, the research team developed a comprehensive evaluation matrix to compare the identified techniques and provided recommendations for consideration by IDOT and other state DOTs.
The project has been instrumental in developing an understanding of the data requirements to implement the HSM to its fullest potential, according to Kolody. “This project tested several methods for collecting data to recommend the most cost-effective, efficient process for obtaining data with the quality and quantity needed for statewide and project-level safety analyses. This is a very important step in moving Illinois toward optimizing safety operations of roadways, improving decision making, and achieving progress toward the goal of zero fatalities.”
The final report and recommendations of this research project, titled “Investigation of Methods and Approaches for Collecting and Recording Highway Inventory Data” (R-27-116), are available on ICT’s website. Implementation is the next step to incorporating the recommendations from the research project into IDOT’s asset management process.