Study Of High Tension Cable Barriers On Michigan Roadways PDF Download

Median-crossover crashes present the highest risk of fatality and severe injury among all collision types on freeways. These crashes are caused by a variety of factors, including drowsiness, driver distraction, impaired driving, and loss of control. The primary countermeasure to reduce the opportunity for such crashes is the installation of median barriers. The Michigan Department of Transportation (MDOT) began installing hightension cable median barriers in 2008 and has installed approximately 317 miles of high-tension cable median barrier on state freeways as of September 2013. Given the capital costs required for this installation program, as well as the anticipated annual maintenance and repairs costs, a comprehensive evaluation was conducted in order to ascertain the efficacy of cable barrier systems that have been installed to date. Statistical analyses showed that fatal and incapacitating injury crashes were reduced by 33 percent after cable barrier installation. The analysis also showed the median-crossover crash rate was reduced by 86.8 percent and the rate of rollover crashes was reduced by 50.4 percent. In contrast, less severe crashes were found to increase by 155 percent after cable barrier installation. A detailed analysis of crashes involving a vehicle striking the cable barrier was also conducted. The results showed that cable barriers were 96.9 percent effective in preventing penetration in the event of a cable barrier strike. Weather and road conditions were also found to play a role in the frequency and severity of crashes, as well as cable barrier performance. An economic analysis was conducted to determine the cost-effectiveness of the cable barrier system, and guidelines were developed to assist in prioritizing candidate locations for cable barrier installation.