Iowa officials credit cable barriers with improving safety

Iowa's early experience with the biggest new thing in highway safety appears to be paying off, according to police and highway officials.

"I think they've made a tremendous difference,” said Coralville Police Lt. Shane Kron. “It's an impressive system.”

Cable barriers - also called guard cables - began going up along interstate highways in Iowa a little more than two years ago. They were installed along Interstate 380 in Johnson and Linn counties last summer.

Although the mild winter was undoubtedly a factor, police and rescue personnel say the cables helped prevent the worst-case scenario: an out-of-control vehicle crossing the median into oncoming traffic.

"There's been times the cars hit the median at a pretty good clip, and there's no question it's stopped them from coming into the oncoming lane,” said Lt. Randy Jones, commander of the Iowa State Patrol's Cedar Rapids-based District 11.

"It's doing its job, it's keeping them from crossing over,” said Cedar Rapids Fire Chief Mark English.

Cable strung along a line of posts has been a roadside fixture in much of the country for more than 80 years, according to an Iowa State University report. In the 1990s, several manufacturers developed high-tension cable barriers: three or four cables tightened to 2,000 to 9,000 pounds of tension, supported on breakaway posts and anchored at both ends.

The DOT's five-year plan calls for cable barrier along 210 miles of Interstates 80 and 380 by 2015. The project will cost $13.9 million, or $66,166 per mile. The cables are going up along the stretches with the most median-crossing accidents.

The cables are designed to bring vehicles to a halt in the median. Cable barrier collisions tend to be less violent than those involving conventional solid-steel guard rails, with fewer injuries, according to Cathy Cutler, the DOT's district transportation planner in Cedar Rapids.

"Those posts snap off really easy, and those cables tend to dig into the front end and hold it rather than bouncing it back out,” said Jones.

According to the ISU report, cable barriers are relatively inexpensive to install but do require repair costs after being struck.

The DOT hired a contractor last fall to repair damage to cable barriers. In Cedar Rapids-based District 6, cable barriers have received $146,358 worth of repairs since Oct. 1, according to Cutler:

•  Cables have been re-tensioned twice after minor accidents, at $100 per repair.
•  1,243 posts replaced at $106 each.
•  Five new concrete pads for post footings, at $300 each.
•  The assemblies that anchor each end of a cable barrier installation have been replaced three times, at $4,300 apiece.

Cutler said DOT crews may take over some cable repair when the contract is renewed this fall. For the year ending last June 30, the state spent $767,967 to repair all types of barriers. Cutler noted much cable barrier was installed after that period, making a direct comparison difficult.

The DOT routinely seeks reimbursement for damaged barriers, signs, and other state property from motorists' insurers.

To keep repair costs down, the DOT has instructed local fire and police departments on removing vehicles from crash scenes without further damage to cable barriers.

"There's certain places to cut and not cut” to retain proper tension after an accident, said English.

Research in other states found a high cost-benefit ratio, according to the ISU report. The North Carolina Department of Transportation estimates its low-tension cable barriers saved 96 lives and $290 million between 1999 and 2003, but the ISU researchers noted variations in traffic density and other factors make it difficult to reliably estimate cost-benefit factors.

The cables are often going up where there were previously no barriers at all, giving motorcyclists a potential hazard should they leave the road.

"We don't really care for the cable barriers,” said Phil McCormick of Clear Lake, state coordinator for the motorcyclists' group ABATE of Iowa. “The steel ones are better. I guess, looking at them, I'd rather not hit either of them.”

Cedar Rapids police records show three accidents in which the barriers were struck. There were no injuries.

In the most serious accident, the cables couldn't halt a dump truck after a front tire blew while the truck was going north at the I-380 rest areas Nov. 15. The truck went out of control, plowed through the cable, and dragged it across the median and into the southbound lane, narrowly missing traffic.

Firefighters at the scene said the truck went partly over rather than through the cable barrier.

Darrell Busch of Marion was driving to work at the Veterans Administration Medical Center in Iowa City when his car became entangled in the cable dragged by the careening truck.

"I don't think they're safe at all,” Busch said of the cables. “They're dangerous.”

As Busch's car went under the cables, another truck ran over them, crushing the car's top.

"I had to be helped out of the vehicle because the roof was collapsed on it,” said Busch, 55.

Still, police and the IDOT are sure the cables have prevented accidents from becoming more serious. Kron said cable barriers reduced median-crossing accidents along Coralville's stretch of I-80.

"I cannot tell you how many times there's a car that went across the median and almost went into the opposite lane,” he said. “That's almost a sure fatality.”