In-Service Safety Performance Evaluation of Roadside Concrete Barriers

Safety-shaped concrete barriers have been the most widely used rigid roadside barriers to shield errant motorists from roadside hazards or obstacles. These barriers are designed to lift impacting vehicles up and thereby extend the duration of impact and reduce the peak decelerations on the vehicle. However, safety-shaped concrete barriers tend to produce rollovers due to excessive vehicle climbing. Vertical concrete barriers, on the other hand, do not have the advantage of reducing impact forces by lifting the vehicle up, but they do produce lower roll angles. The objective of this research was to evaluate which of these two barrier profiles is the safest based on real-world vehicle crash data. The safest profile was defined as the one that produced lower driver injury severity levels and rollover propensity. It was found that safety-shaped barriers are more likely to produce rollovers as compared to vertical barriers. It was also found that crashes involving safety-shaped barriers tended to result in more severe driver injury levels. This finding was not statistically significant though. However, rollovers were found to significantly increase driver injury severity levels. Therefore, it is believed that the expanded use of vertical concrete barriers should improve overall highway safety.