December 10, 2003
Refer to: HSA-10/CC-35F
Barry D. Stephens, P.E.
Senior Vice President of Engineering
Energy Absorption Systems, Incorporated
3617 Cincinnati Avenue
Rocklin, California 95765
Dear Mr. Stephens:
In your November 15, 2003, letter to Mr. Richard Powers of my staff, you requested formal Federal Highway Administration acceptance of a parallel-sided QuadGuard CZ mounted on a 42-inch wide A-36 steel plate anchored to the ground. A design in which the QuadGuard CZ was anchored directly to the ground was accepted via Mr. Seppo Sillan's August 5, 1996 letter to your Mr. Roger Egan (acceptance letter CC35A). By mounting the crash cushion on a steel plate, it becomes easier to install, maintain, and eventually remove or relocate on an active construction site. The two-piece steel plate used in the test was 3/8-inch thick and was anchored through
6 inches of asphalt and approximately 8 inches of compacted base course using 30 ¾-inch diameter threaded steel rods (ASTM A193-B7) and a two-part polyester grout. The steel rods were 18-inches long. The tested design is shown in Enclosure 1.
To verify acceptable crash performance of the QuadGuard CZ mounted on steel plates, you ran National Cooperative Highway Research Program (NCHRP) Report 350 test 3-33, which members of my staff had previously agreed would likely place the greatest loading on the plate anchoring system. The crash cushion functioned as designed and the steel plate remained flat with no sign of lifting or bending. Since this test had been successfully run much earlier on a permanent QuadGuard, you did not instrument the truck used in the test so no occupant risk values were recorded or reported. Enclosure 2 is the test summary sheet. You had previously conducted test 3-38 into the side of QuadGuard CZ mounted on a ¾-inch thick steel plate. In this test, the pickup truck was contained and redirected and, again, the steel plate showed no evidence of distress after the crash.
I agree that the QuadGuard CZ, in widths up to 36 inches, may be mounted on a steel plate with a minimum thickness of 3/8 inch, when anchored through asphalt as tested or when anchored as per your specifications through 6 inches (minimum) of concrete. Its NCHRP Report 350 test level rating remains the same as for a permanent installation and is dependent on the number of bays used in a specific application.
(original signed by John R. Baxter)
John R. Baxter, P.E.
Director, Office of Safety Design
Office of Safety