Based on five full-scale crash tests and a series of computer simulations, the performance of the concrete safety-shape barrier (CSSB) with the New Jersey profile was found to be acceptable for impact conditions recommended in NCHRP Report 230 for evaluation of safety appurtenances. Vehicle sizes ranged from minicars weighing 1,250 lb to large cars weighing 4,500 lb. All tests recommended in NCHRP Report 230 are conducted with the vehicle impacting in a tracking mode; however, it is estimated that approximately 50% of inadvertent off-the-road vehicle encroachments occur in a nontracking mode. Hence, a modified version of the Highway-Vehicle-Object-Simulation Model (HVOSM) was used in studying the performance of the CSSB for nontracking and tracking impacts with high angle/speed combinations. The modified HVOSM program was subjected to an extensive calibration effort and found to produce reasonably accurate results. It was determined that overturns can be expected for small cars in nontracking and/or high angle impacts with the CSSB. Performance of potential new shapes of rigid longitudinal barriers were also studied. A barrier with a constant-slope face or a vertical wall will greatly reduce the overturn problem. A retrofit design for the CSSB consisting of a longitudinal member placed on the side of the barrier near the top also showed promise in reducing this problem.
Samenvatting