September 5, 2002
Barry D. Stephens, P.E.
Senior Vice President – Engineering
Energy Absorption Systems, Inc.
3617 Cincinnati Avenue
Rocklin, CA 95765
Dear Mr. Stephens:
In your July 1 letter to Mr. George Ostensen, you requested Federal Highway Administration's (FHWA) acceptance of a w-beam guardrail terminal called the REGENT-C. To support this request, you also sent copies of a report prepared by E-TECH Testing Services, Inc., dated May 2002, entitled “NCHRP Report 350 Crash Test Results for the REGENT-C System” and videotapes of the tests that were conducted.
The REGENT-C is a non-energy absorbing w-beam terminal installed with a straight flare and offset 1.2 meters from the barrier proper at the end of its 11.43 m length. The terminal uses modified w-beam panels containing engineered slots and includes a 19-mm diameter 6 x 9 wire rope nested into the traffic-face of the w-beam. The modified rail elements significantly reduce the column strength of the system, allowing it to collapse in an end-on hit. The nested cable increases the tensile strength of the rail to provide redirection for a side impact beyond post 3, the beginning of the terminal length of need. The REGENT-C uses a standard strut and cable end anchorage and seven 150 mm x 200 mm x 1830 mm weakened wood posts to support the rail. These and other design details are shown in Enclosure 1.
NCHRP Report 350 tests 3-30, 3-31, and 3-35 were successfully conducted on the REGENT-C. Tests 3-32, 3-33, 3-34, and 3-39 were not run because you believed that they were less demanding than the tests that were run and thus not needed. I agree that these tests can be waived. Summary sheets of the three tests you conducted are shown in Enclosure 2. Since the pickup truck came to a stop straddling the rail approximately 45 m downstream from the terminal, this is the minimum length of rail that should be installed when the barrier is used along a high-speed roadway to shield a bridge parapet or a vertical rigid object located directly behind the guardrail. I note also that all three tests were conducted with the terminal set in an NCHPR Report 350 weak soil, thus making its use with any soil acceptable.
Based on staff review of the information you submitted, I concur that the REGENT-C meets the evaluation criteria for an NCHRP Report 350 w-beam guardrail terminal at test level 3 (TL-3) and, subject only to the condition noted above, it may be used on the National Highway System when such use is acceptable to the highway owner. Because it is a proprietary device, its use on federal-aid projects, except exempt, non-NHS projects, is subject to the conditions in Title 23, Code of federal Regulations, Section 635.411.
(original signed by Carol H. Jacoby)
Carol H. Jacoby, P.E.
Director, Office of Safety Design