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Publication Number: FHWA-SA-96-016
Date: May 1996
The second generation prototype of the portable crash cushion trailer is now ready for field testing. Initially developed as part of the Strategic Highway Research Program (SHRP), the device allows work crews to quickly deploy sand-filled barrels to close a traffic lane or shield construction equipment in a work zone. The barrels can be used at work sites and stationary obstacles to protect highway workers and cushion the impact of a crash.
Setting up crash barrels is an arduous and time-consuming job that exposes workers to considerable danger. By making the process easier and faster, the risk to workers is lessened because the barrels are likely to be used more often. This would be a boon to the safety of workers and motorists alike.
The portable crash cushion trailer is a tilt-bed trailer equipped with a pallet of hinged steel plates. Sand-filled barrels are secured to the pallet, and a winch is provided to assist in installation and removal of the barrels. Rollers on the trailer bed allow the pallet to easily slide on and off the trailer.
The second generation prototype overcomes two problems that had been found in field testing. The first was that the sand barrels could be loaded and unloaded from one direction only--the lightest barrel had to be unloaded first. In some situations, this made setting up the portable crash cushion difficult. The other problem was that the 12-m-long (40-ft) trailer was too big for narrow roads and for many work zones.
The new version addresses both problems, says Harry Taylor, highway engineer at the Federal Highway Administration (FHWA). The trailer can now be loaded with either the heavy barrels or the light barrels at the front, in preparation for unloading at a particular site.
The revised prototype is also half as long as the original design, with only four hinged segments to the pallet. "By basically cutting it in half, we made it much easier to maneuver," Taylor says. "While that means you have to make two trips to bring as many barrels, we think it's worthwhile." He adds that the improved design's greater maneuverability should make it safer for crews to load and unload.
Deploying a crash cushion in two sections has another advantage, Taylor notes. If one half of the crash cushion is struck by a vehicle and destroyed, the highway agency can replace just the damaged section rather than the complete array.
The improved trailer, built by Williamsen Manufacturing Inc., is now headed for testing and evaluation in five states. Alabama, California, Minnesota, and New York will evaluate the second-generation prototype in its basic form. Iowa, which is currently testing the original trailer, will evaluate a slightly modified model designed to carry heavier barrels and to be deployed behind the original trailer. "This heavier version gives protection against everything from small cars to 8,000-kg (18,000-lb) trucks at 90 km/h (55 mi/h)," says Taylor. "It's the first crash cushion for work zones that is effective against trucks."
It will come none too soon for the Iowa Department of Transportation (DOT). Just last month a semitrailer crashed into a truck-mounted attenuator (TMA) at an Iowa DOT work site on Interstate 80, reports Lee Smithson, deputy director of the maintenance division at Iowa DOT. The semitrailer burst into flames, and the driver was badly hurt. The Iowa DOT crew member driving the TMA truck was also injured and was expected to be off the job for at least 30 days. "We need more protection out there," Smithson says.
For more information, contact Harry Taylor at FHWA, 202-366-2175 (fax: 202-366-2249).
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