Federal Highway Administration
400 Seventh St., S.W.
Washington, D.C. 20590
October 27, 2006
In Reply Refer To: HSA-10/B-150
Mr. Andrew Artar
Vice President Sales and Marketing
Gregory Highway Products
4100 13th Street, SW
Canton, Ohio 44710
Dear Mr. Artar:
In your September 28, 2006 letter, you requested Federal Highway Administration (FHWA) acceptance of a new strong post W-beam guardrail design that incorporates a proprietary fastener, called a Gregory Mini Spacer (GMS), in lieu of a standard guardrail bolt. This new connector was designed to improve the crash performance of W-beam guardrail. You also sent copies of test reports prepared by the Southwest Research Institute documenting the performance of your design and videotapes of the two tests that were conducted on a strong-post W-beam that did not use offset blocks. Test 3-10 was conducted on a double-sided (median) barrier using the current NCHRP 820C car, and test 3-11 was conducted on a single-sided (roadside) installation using a quad-cab pickup truck with a nominal weight of 2270 kg.
The GMS system was tested with 12-gauge W-beam panels mounted directly onto standard, unmodified W6 x 8.5 steel posts with no offset blocks and with a top-of-rail height of 31 inches. The rail was attached to each post using a 5/16-inch diameter standard hex head bolt. Design details for the proprietary GMS fastener are shown on Enclosure 1 and the two test summary sheets are shown on Enclosure 2.
Based on the reported test results, the GMS system as described above is classified as a test level 3 barrier and may be used on the National Highway System when such use is acceptable to the contracting authority. Additionally, the GMS fastener may be used in place of a standard guardrail bolt on any non-proprietary strong or weak post W-beam guardrail designs that currently meet NCHRP Report 350 test and evaluation criteria, exclusive of transition designs and end treatments. Such usage will not change the test level of the barrier on which it is used and is based on the assumption that the GMS fastener is likely to improve the crash performance of all W-beam barrier systems because of its predictable and consistent beam release characteristics. This assumption should be verified through in-service evaluations to the extent practical.
Please note the following standard provisions that apply to the FHWA letters of acceptance:
/original signed by/
John R. Baxter, P.E.
Director, Office of Safety Design
Office of Safety
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