In an effort to increase highway safety, Missouri has been installing high-tension guard cables in Interstate medians for the last ten years. However, these cable barriers are not designed to handle the force of a semi and do not stop some semi crossovers.
In June, 2013, a trucking accident in Evansville, Indiana, involved similar cable barriers. A Schnucks semi traveling eastbound crossed the cable barrier-protected median, and struck a westbound tanker. A car was unable to avoid the Schnucks semi and struck the back end of the truck. Five were hospitalized and one was killed. According to George Ballard, the Gibson County Sheriff, the cables didn’t break, but were still attached to the semi when it crossed through the median and passing lanes.
The cable systems in Missouri cost around $105,000 per mile to install and are being installed on routes that have traffic volumes of over 20,000 vehicles per day. Metal guardrails, on the other hand, cost around $200,000 per mile. In 2005 and 2006, the cable systems were installed on Interstate 55 from Sikeston to Oak Ridge, MO. The cable systems were installed along Interstate 70 in 2006.
The Gibraltar cable barrier system used by MoDOT is produced by a Texas company. They are comprised of ¾ inch woven steel cables that weigh around 1 pound for each foot. These cables are connected with large anchors to square steel pipes, mounted in concrete, eight feet away from the traffic lane. Turnbuckles allow the tension to be adjusted on the cables. These cables are kept at a tension of 5,000 pounds, but because heat can cause the cables to expand, which lowers the tension, the cables must be monitored and adjusted.
According to Andy Meyer, the construction materials engineer for the Missouri Department of Transportation, “Five thousand pounds of tension allows it to hopefully absorb the impact of a car or light truck.” Meyer also stated that “There are still a lot of vehicles that are too big, or traveling at such a speed, or bouncing around such that the median is unable to completely stop them.” Therefore, while the cable barriers may increase highway safety by reducing crossover accidents in cars and SUVs, they aren’t as likely reduce crossover trucking accidents.