Preface

Roadside safety devices are designed to reduce the risk of occupant injuries when a vehicle runs off the road. New devices are evaluated by crash testing: the device is installed at a test facility, a vehicle collides with it, and engineers assess the consequences of the crash. Guardrails are roadside safety devices installed at locations that do not provide a clear zone in which a vehicle can decelerate without striking an object or encountering unsafe terrain. The end of a length of guardrail must be designed so that it is not a hazard to occupants of a vehicle striking it. Highway agencies install end treatments in a variety of forms intended to absorb energy in a crash and to redirect the vehicle into a safe trajectory. The Transportation Research Board formed a committee with the sponsorship of the National Cooperative Highway Research Program (NCHRP) to develop a research design for evaluating the in-service performance of guardrail end treatments, determine the data required for the analysis, examine state data systems to determine whether the required data would be available, and identify next steps for carrying out evaluations. The committee's conclusions about the objectives of in-service evaluation of end treatments and other roadside safety devices and about current capabilities and evaluation methods for conducting in-service evaluations are summarized next, followed by recommendations for proceeding with evaluati.