Existing and potential methodologies for evaluating in-use safety performance of roadside safety equipment

This paper summarizes the findings of a recent review of practice- and research- methods related to the In-service Performance Evaluation (ISPE) of roadside safety equipment installation and, more specifically, guardrail end treatments. The review was necessitated by the need for state agencies to measure performance of roadside safety hardware beyond crash tests. It focused on guidance for the field collection of data and analytical methods related to agency ISPE process goals. It encompassed both road safety literature for existing methods as well as research studies from other fields to identify methods that may also have the potential to be applied by state departments of transportation to enhance their ISPE process. This paper summarizes the three primary areas, including 1.) Existing ISPE processes and goals; 2.) Research designs and analysis techniques for observational data analysis; and 3.) Practices of rare-event analysis from other fields of study. The review also showed that analysis objectives and methods are influenced by the cost, time, and effort to collect data to implement the methodology, but that other sources of road/crash characteristics not commonly used in ISPE studies like roadway crash databases can be valuable input to the ISPE process. In terms of rare event analysis work from other fields, it was found that most of the existing identification, assessment, modeling, forecasting, and classification techniques from other areas of study currently have limited potential for application in the ISPE of guardrail end treatments. However, as sensor technologies evolve and enhance the ability to monitor infrastructure and archive large safety data with higher reliability and lower cost, some of these techniques can become part of the ISPE process.