EVALUATION OF A MODIFIED STEEL POST W-BEAM GUARDRAIL SYSTEM

In May 1993, a set of revised test procedures was published in National Cooperative Highway Research Program (NCHRP) Report 350, "Recommended Procedures for the Safety Performance Evaluation of Highway Features." The Federal Highway Administration (FHWA) formally adopted these new test procedures and has mandated that, after September 30, 1998, only highway safety appurtenances that have successfully met these guidelines may be used in new projects on the National Highway System (NHS). The most significant change made in the new guidelines with regard to the evaluation of longitudinal barriers was the adoption of a 2000-kg pickup truck (2000P) as a design test vehicle. Since most existing longitudinal barriers have been tested with a large passenger sedan, it was necessary to reevaluate the performance of these barriers with the new pickup truck test vehicle. As part of this reevaluation process, the FHWA sponsored the crash testing of many commonly used guardrail systems. A test of the widely used G4(1S) steel post W-beam guardrail system indicated that this system was not in compliance with the new NCHRP Report 350 guidelines. This report presents the results of a crash test on a modified steel post, W-beam guardrail system that incorporates 152-mm x 152-mm routed wood blockouts. This modified steel post guardrail system successfully met the performance evaluation criteria of NCHRP Report 350. Although the vehicle became completely airborne during the impact sequence, it remained upright and was successfully contained and redirected.