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Cable Median Barriers

This page last updated June 3, 2019

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Back in the early 2000s, there were a number of serious head-on collisions on San Antonio area freeways that had no center median barrier. After a rash of these along Loop 1604, TxDOT installed portable concrete Jersey barriers in the median of 1604 and announced that they would be installing cable barriers in the medians of other area highways as part of a statewide effort to do so. As often happens, the second-guessing began almost immediately. Skeptics bellowed that the "flimsy" barriers wouldn't even stop a Yugo, let alone an 18-wheeler. But TxDOT's engineers defended the barriers and insisted that they would work as intended. And indeed, in the first two years that cable barriers were in place in the San Antonio area, they stopped every single vehicle that hit them, including an 18-wheeler on I-35 in Von Ormy.

A before-and-after study in 2007 after 335 miles of cable barriers were installed around the state showed that the number of fatalities on those roads where the barriers were installed dropped from 52 fatalities in the year before installation to just one fatality in the year afterward. In short, the barriers work and work well.

In fact, cable barriers are often better than metal guardrails and concrete Jersey barriers because they absorb more of the energy of the impact than do those traditional barriers, thus reducing the chance of injury and lessening the damage to vehicles that collide with them. They also reduce the number of "rebound" accidents where a vehicle hits the barrier and then bounces-back into the traffic lanes. All these benefits come at an installation cost that is typically 25% the cost of concrete barriers. Maintenance costs for cable barriers are higher, but are often paid by the insurance policies of the drivers who collide with them, and a survey of TxDOT districts showed that maintenance was often faster and easier than with other barriers.

Successful cable-barrier capture of an 18-wheeler
(Source: Washington Department of Transportation)

One understandable concern is what happens to motorcyclists who hit the barrier. It would seem to be common sense that the cables pose a signficant risk of injury to riders. This has led to some motorcyclists referring to cable barriers as "cheese cutters". However, several studies have been done in the US, Europe, and Australia on this issue and have generally concluded that the statistical evidence to date shows that cable barriers are no more dangerous to motorcyclists than other barriers.

A while back, a driver involved in a collision that sent her vehicle into the cable barrier on I-10 near Boerne was upset because the barrier had sliced into her car and had caused significant damage. However, she was uninjured and the barrier quite likely saved her life, or at least prevented serious injury. Had it not been for the barrier, she almost certainly would have gone into the oncoming traffic and probably been struck head-on or T-boned by traffic going 70 mph. Furthermore, her vehicle likely would have suffered equal or greater damage if there had been a traditional guardrail or concrete barrier instead.

As of late 2009, Texas had about 800 miles of cable median barrier installed.


Other sites of interest

Federal Highway Administration
http://www.fhwa.dot.gov/crt/lifecycle/cable.cfm
American Association of State Highway and Transportation Officials
http://tig.transportation.org/?siteid=57&pageid=2197
USA Today article
http://www.transportation.org/sites/aashtotig/docs/USA%20Today%20Article%20-%20072006.pdf




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This page and all its contents are Copyright 2019 by Brian Purcell

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