This project aims to reduce the number of vehicle penetrations through cable guardrail systems. The project consist of three distinctive approaches to improving cable barrier design guidelines: qualitative, analytical investigation of cable barrier crashes resulting in penetrations; computer simulation of a cable median barrier crash in order to capture the penetration mechanisms of cable barrier systems; and improving cable barrier simulation components for future crash simulations which will better predict penetrations and propensity for underride or override. The combination of approaches will provide insight into the mechanisms leading to cable barrier penetrations in order that design modifications and guidelines may be recommended to reduce the number of cable guardrail penetrations.
The research objective is to increase the capacity of cable median barriers in order to reduce the number and frequency of crossover crashes resulting from penetration through cable median barriers.
The benefits of research are threefold: (1) guidelines for construction and design of new cable barrier systems will be created to reduce the propensity for penetrations to occur; (2) models of cable guardrail system components and interactions will be refined; and (3) qualitative assessments of cable barrier penetrations will enable researchers investigating alternative guardrail system failures to identify critical impact parameters.
Cable median barrier has proven to be an effective safety treatment for prevention and cross median crashes in rural and suburban areas. A recent study of the effectiveness of cable median barrier in Missouri showed that it reduced fatalities resulting from cross median crashes by approximately 95%. Even though existing barriers are 95% effective, the remaining 5% of fatal crashes in Missouri, when extrapolated by population to the entire nation, are estimated to represent approximately 250 fatalities annually. Thus, there is still a great opportunity for improving highway safety by improving cable median barrier performance. This study will attempt to determine the combinations of median configuration, vehicle type, and impact conditions that lead to a fatal crash. This effort will involve qualitative evaluation of reported fatal crashes involving cable median barriers. Although a majority of these crashes are likely to involve cross median encroachments, a significant portion will involve fatalities caused by the cable barrier itself. The top combinations of median configuration, vehicle type, and impact conditions associated with fatal crashes will be selected or further study. Results from a recently completed MATC funded study (2) will be utilized to provide advanced finite element modeling of representative crashes for the most important categories identified in the accident study. It is anticipated that findings from the previous study can be incorporated statistically improve simulation accuracy. Further, reevaluation of testing conducted under the prior study should provide additional information such as the relationships between cable tension and its bending and torsional stiffnesses. Findings from the computer simulation of the fatal crashes will then be utilized to identify cable barrier design enhancements that can reduce or eliminate these types of crash outcomes. Findings from the study will then be documented with both a final report and a refereed journal article.