"TRB Special Report 323, In-Service Performance Evaluation of Guardrail End Treatments, develops a research design for evaluating the in-service performance of guardrail end treatments and other roadside safety devices and identifies the data required to do so. Given the substantial data requirements and methodological challenges of conducting successful evaluations of particular end treatments, the committee concludes that state highway agencies will require more information about the benefits, costs, and practicality of routine in-service evaluation of end treatments in general before deciding to undertake new data collection and analysis programs necessary to carry out more challenging analyses. The committee recommends research to advance practice and test the feasibility of and costs associated with more complex evaluations. It also recommends research to examine whether procedures for testing the performance of devices should be altered"--Provided by publisher.