Subject: Cable Median Barriers – Part 1 Topic: Cable Median Barrier Incident Considerations Objective: Responders shall develop procedures for operations at center median incidents when a vehicle is contacting or entangled in tensioned cables Task: The rescue...
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Subject: Cable Median Barriers – Part 1
Topic: Cable Median Barrier Incident Considerations
Objective: Responders shall develop procedures for operations at center median incidents when a vehicle is contacting or entangled in tensioned cables
Task: The rescue team shall determine the presence of high-tension cable median barrier systems within their response district and develop procedures for incidents with vehicles in contact with the cable systems
As responders who respond to incidents on divided highways, we have dealt with collisions where one vehicle left its lane of the highway, crossed through the center median and collided violently with on-coming traffic with devastating results. In fact, in the few years prior to 2003, virtually all fatalities on interstate highways in the state of Texas (96%) were the result of cross-median crashes. To address this staggering statistic, the Texas Department of Transportation (DOT) actively began installing high-tension cable median barriers as a means of minimizing the effects of these cross-over collisions. Other states are following suit. North Carolina was the first to embrace guard cable installations on all of its interstate highways.
The original cable median barrier systems that became prevalent in the 1980s and ’90s are low-tension systems. The type of median barrier that is now becoming increasingly popular consists of three or four tensioned steel wire cables mounted on break-away steel posts. Cable post spacing for these barriers is typically 6½ to 15 feet apart. Once installed, the three-quarter-inch-thick, three-strand wire cables are tightened to a specific tension; typically 2,000 to 9,000 pounds of force. High-tension cable median barriers function by capturing, entangling, and redirecting the out-of-control vehicle as it slows to a halt but does not contact opposing traffic. Tensioned cables are more forgiving than traditional concrete barriers or the common steel W-shaped guardrails used today.
When responders arrive at an incident involving a vehicle that has crossed into the center median of an expressway and contacted a tensioned cable median barrier, the vehicle may be found touching, stretching or entangled in any or all of the three or four cables. Most likely, many of the steel posts near the crashed vehicle will be destroyed, broken or torn away during the collision by design.
If access to an occupant is obstructed by a cable stretched across the door or roof of a vehicle, the cables themselves may have to be dealt with. Even without patients obstructed, towing and recovery operations may be hindered when these cables are found snagged on a damaged vehicle.
Cutting the Cable
Responders may think that cutting the cable to gain better access is the easy and logical thing to do. It is easy, but it is very dangerous unless done correctly. Cutting a tensioned steel cable, although possible with a rotary saw or a hydraulic power cutter, should not be the rescue team’s “Plan A” tactic; it should be your last-resort tactic! When there are life-threatening injuries and the patients cannot be extricated without cutting the cables, there is a recommended procedure that is explained later in this column.
Instead of cutting the cables, crews should develop a flowchart of other tactics that can be used for tensioned cable entanglement. One of the first considerations in dealing with the cables should be to try to move the cables out of the way. Try lifting or lowering the cable out of the way of the door or roof area of the vehicle. A crew of personnel may be able to accomplish this manually.
If the cable won’t budge, a second tactic should be to consider removing support posts closest to the vehicle. If the posts are loose within their ground mounts, they can be lifted from their mounts or cut through near their base. This may create slack in the cables contacting the vehicle, again allowing the cables to be moved out of the way. If you start to raise the cables and the nearby support posts begin to lift also, be careful. It may be under significant tension if the cables are twisted around a vehicle. As you pull the post out of the way, it may be beneficial to secure the post with a chain or restraining device to prevent unwanted movement.