Impact Performance and an Evaluation Criterion for Median Barriers

This study involved the determination of the impact performance of the Texas Metal Beam Guard Fence median barrier (MBGF) and a comparison of its performance with that of the Texas Concrete Median Barrier (CMB). The MRGF consists of two standard W-shaped guardrails mounted back-to-back on a 6 WF 8.5 support post whereas the CMB is a solid concrete barrier. The impact performance of the MBGF was determined from a combination of crash tests and from crash simulations by the Highway-Vehicle-ObjectSimulation-Model (HVOSM). Standard size automobiles were used in both the crash tests and the crash simulations. A close comparison of test and simulated results verified the accuracy of the HVOSM in simulating impacts with the MBGF. The impact performance of the CMB was obtained from another study. Inspection of 135 median barrier impacts on various urban freeways in Texas were made to determine the distribution of impact angles. These field measurements, supplemented by data from the HVOSM, provided impact angle probabilities as a function of median widths. The final product of this study was an evaluation criterion which provides an objective means of comparing the impact severity of the MBGF and the CMB as a function of the median•s dimensions. The criterion is based on a design speed of 60 mph, and impacts with a full-size automobile.