NCHRP Report 350: Recommended Procedures for the Safety Performance Evaluation of Highway Features contains the current guidelines for evaluating the safety performance of roadside features, such as longitudinal barriers, terminals, crash cushions, and breakaway structures. This document was published in 1993 and was formally adopted as the national standard by the Federal Highway Administration (FHWA) later that year with an implementation date for late 1998. In 1998, the American Association of State Highway and Transportation Officials (AASHTO) and FHWA agreed that most types of safety features installed along the National Highway System must meet NCHRP Report 350 safety-performance evaluation criteria.
A recommended update to NCHRP Report 350 has been developed under NCHRP Project 22-14(02), "Improvement of Procedures for the Safety-Performance Evaluation of Roadside Features." This document contains revised criteria for safety-performance evaluation of virtually all roadside safety features. For example, the update recommends testing with heavier light truck vehicles to better represent the current fleet of vehicles in the pickup/van/sport-utility vehicle class. Further, the new guidelines increase the impact angle for most small car crash tests to the same angle as the light truck test conditions. These changes will place greater safety-performance demands on many of the current roadside safety features.
State DOTs make considerable use of non-proprietary systems (such as weak-post w-beam, low-tension three-strand cable barrier, and box beam). Although some barrier testing has been conducted during the development of the updated criteria, many barrier systems and other roadside safety features have yet to be evaluated under the proposed guidelines. Therefore, evaluation of the remaining widely used roadside safety features using the safety-performance evaluation guidelines included in the update to NCHRP Report 350 is needed.
The objective of this project is to evaluate the safety performance of widely used non-proprietary roadside safety features by using the proposed update of NCHRP 350. Features may include longitudinal barriers (excluding bridge railings); terminals and crash cushions; transitions; and breakaway supports. Evaluation methods may include, but are not limited to, engineering assessment, simulation, full-scale crash testing, pendulum testing, and component testing. Where practical, cost-effective modifications to systems that do not meet the new criteria will be recommended for future evaluation.
Accomplishment of the project objective will require at least the following tasks.
TASKS (1.) Identify non-proprietary roadside-safety features and their frequency of use by state DOTs. This may include review of the FHWA safety hardware website (safety.fhwa.dot.gov/report350hardware) and/or a survey of state DOTs. Results of this task will be a list of roadside-safety features and an indication of how frequently (e.g., high, medium, or low usage) the devices are used by state DOTs. (2.) Review information, such as results of crash tests and finite element modeling, that may be applicable. Create a framework (or matrix) for identifying the roadside hardware features that may need evaluation using the proposed new criteria by test level. Include in this framework, information on judgment of expected performance, results of prior crash tests, and findings of crash simulations. (3.) Submit an interim report that documents the framework, describes the options for evaluation, estimates the costs of specific evaluation efforts, and offers the contractor's recommendations for the evaluations that will have the most benefit. (4.) Meet with the NCHRP panel to review the Task 3 interim report approximately 1 month after its submittal. Submit a revised interim report and an updated work plan reflecting the panel's decisions. (5.) Execute the approved work plan to undertake the selected evaluations. Submit standard testing and/or crash simulation reports to the NCHRP as they are completed. Crash test videos should be submitted as soon as they become available. (6.) Submit a final report documenting the entire research effort. The final report shall describe how the project was conducted and include appendixes documenting the specific evaluations undertaken.
Status: The project has been completed and the final report published.
Product Availability: Research results Digest 349, "Evaluation of Existing Roadside Safety Hardware Using Manual for Assessing Safety Hardware (MASH)."