Topeka Kansas transportation officials are trying to decide whether installing guard cables in highway medians would be worth the cost and actually make it safer to drive in the state.
A study conducted for the Kansas Department of Transportation concludes that the cables — already in place in 25 other states, including Missouri — can help save lives in some instances, but might not be all that helpful in others.
“We’ve always known you could reduce the potential for fatalities” with guard cables, said Jim Brewer, engineering manager in KDOT’s design bureau. “But if you increase the potential for injury and property damage … then you may not have improved the system.”
According to the study, conducted by a national traffic safety expert at the University of Nebraska, the cables work best on highways with narrow medians and high traffic.
But they can pose a risk on highways with wide medians and low traffic — characteristics of many Kansas roads.
“The cable is always there, no matter how light the traffic volume gets,” said Dean Sicking, the Nebraska expert who directs the university’s Midwest Roadside Safety Facility. “If you get to the middle of the median, you’re going to hit that cable.
“But as long as the volume goes down, the risk of hitting somebody in the opposing lane drops off real fast.”
Kansas started looking into the cables in the summer of 2007 when five people were killed in crossover crashes, including three in a collision on Interstate 435 in Lenexa.
Sicking’s study was meant to help the state choose where guard cables could be installed without paying the $100,000 per mile cost in places where they aren’t needed.
From 2002 to 2006, Kansas averaged 5.6 highway deaths per year caused by crossover accidents.
That’s not a big number compared with the average of 270 fatalities in all other crashes, the study said.
KDOT officials hope to decide by March whether to install the cables.
Missouri has had them on its highway medians since 1999, with 500 miles of cables including 75 miles in the Kansas City area.
State highway officials say the cables have reduced traffic fatality rates.
But Missouri’s interstate highways have narrower medians — most about 40 feet wide — with steeper embankments than in Kansas, where medians on Interstate 70 tend to be wider and flatter, giving drivers a better chance to recover if they run off the road.