Cable barrier systems: Do they work?

Cable barriers

As friends and family remember the eight people killed in a crash involving a bus on Interstate 40 in Jefferson County, we're getting the facts on whether cable barriers really do any good.

The Tennessee Highway Patrol says the bus driver lost control after a tire malfunction, crossed through the median and through a cable barrier, before crashing into a tractor-trailer and SUV.

Up and down Tennessee's interstates are different barrier systems designed to keep you safe. "They do help a lot," says David Lewis with the Tennessee Department of Transportation.

Wednesday, the cable rail system on I-40 didn't stop a bus from crossing through it and into oncoming traffic. "40,000 pounds is going to push that over," says Sgt. Bill Miller with Tennessee Highway Patrol.

Both TDOT and THP tell us nothing could have stopped that bus; TDOT says the cable barriers are more effective at stopping cars, as opposed to tractor-trailers and buses.

TDOT says lane departure crashes account for over 62 percent of traffic fatalities in Tennessee, which is over 600 deaths last year.

Lewis tells us they began installing cable railing systems a few years ago in sections of the interstate where the most crossover crashes occurred. He says the benefit over a guardrail or concrete barrier is that the railing system absorbs more of the impact, and sometimes keeps cars from bouncing back into the interstate. "When a car or vehicle gets over into it, they have a lot of tension.  They're fixed where the cable can wrap around the wheel," says Lewis.

But as far as tractor trailers and buses go, "Most of the time, they're just so big and tall and they've got a lot of force behind them, they'll go through most anything," Lewis explained.

TDOT says they're constantly evaluating the effectiveness of the cable barrier, and while no barrier is 100d percent effective at interstate speed, any crash has potential for disaster. 

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