Median cables along busy interstates usually prevent cars from entering oncoming traffic lanes in the event of a collision, but this was not the case in a Dec. 13 accident just east of Newton along Interstate 80.
Douglas Lauridsen, 46, of Altoona was traveling eastbound when he fell asleep, causing him to drift toward the westbound lanes. His vehicle broke through the median cables, entered the ditch and rolled one and a half times before it stopped, and emergency response crews helped Lauridsen out of the vehicle.
Lauridsen did admit that he had been drinking earlier the day of the accident and that he had taken cold medication. His blood alcohol content was .051, below the legal limit. He did not sustain any serious injuries but was taken to Skiff Medical Center. He was cited with failure to maintain control in the accident, which caused an estimated $2,500 damage.
Iowa Department of Transportation Roadside Design Engineer Chris Poole said that median cables, which were installed last summer, are designed to prevent cars from crossing lanes of traffic by sustaining most of the damage themselves.
“Cables are supposed to grab the vehicle and contain it, and they’re reusable in most accidents unless there is significant damage.” Poole said. “The cables don’t usually snap. They stretch.”
Median cables are designed similar to ropes and farm cables, with each end tightly secured to prevent breakage. The barriers consist of three steel cables suspended by posts placed every 20 feet along the roadside.
“Each cable has 21 wires like a rope,” Poole said. “Once one breaks, you splice a new section. They are highly reusable with a 15-20 year life expectancy.”
The cables, which are mostly used in rural areas, can benefit both the vehicle and driver in a collision by absorbing some of the impact, resulting in less severe injuries to drivers. Despite this benefit, many of the older styles of barriers remain along highways throughout the state.
“We do the best to maintain old barriers,” Poole said. “We still use concrete and steel beams.”
Concrete beams may be more stable, but the cost of maintenance can be steep. In addition to repairs from accidents, the state must consider the cost of weather-related issues. Constant expansion and contraction due to Iowa’s seasonal climate can cause stress on concrete structures. In addition, the barriers often create snow drifts during the winter months.
Repairing a cable barrier, on the other hand, is very simple. If a post is damaged, like the accident near Newton, it can slide off and be replaced; usually repairs like this take no longer than a few weeks.
Staff writer Matthew Shepard may be contacted at (641) 792-3121, ext. 425, or at firstname.lastname@example.org.