Federal Highway Administration
400 Seventh St., S.W.
February 8, 2008
In Reply Refer To: HSSD/CC-104
Barry D. Stephens, P.E.
Sr. Vice President Engineering
Energy Absorption Systems, Inc.
3617 Cincinnati Avenue
Rocklin, CA 95678
Dear Mr. Stephens:
Thank you for your January 3, 2008, letter requesting Federal Highway Administration (FHWA) review and acceptance of a new Trailer Truck-Mounted Attenuator (TMA), called the Vorteqtm TMA, for use on the National Highway System (NHS). You requested acceptance at the National Cooperative Highway Research Program (NCHRP) Report 350 test level 3 (TL-3). To support your request, you supplied a copy of the January 2008 E-TECH Testing Services, Inc. compliance Report No. 320 entitled “NCHRP Report 350 Crash Test Results for the VorteqTM Trailer TMA.” The report describes the new Vorteq Trailer TMA as well as the four full-scale crash tests you conducted on this safety device.
The FHWA guidance on crash testing of roadside safety hardware is contained in a memorandum dated July 25, 1997, titled “INFORMATION: Identifying Acceptable Highway Safety Features.”
The Vorteq Trailer TMA consists of six major assemblies: an Impact Head, Rear Collars, Frame Tubes, X-Brace, Tongue, and Suspension. The TMA is a nominal 6985 mm long by 2340 mm wide by 770 mm tall (22.9’ x 7.6’ x 2.5’). The 4980 mm (196”) long Frame Tubes are the principle energy absorber in the system and are fabricated from 76 mm OD by 3 mm thick (3” x 0.120”) ASTM A513 Type 1 HREW (Hot Rolled Electric Welded) low carbon steel tubing. The Frame Tubes absorb the energy of the crash as they tightly curl inward when the Impact Head is forced forward.
All four NCHRP Report 350 tests for TMAs were conducted: 3-50 and 3-51 (both required) and 3-52 and 3-53 (optional tests). In each of the four tests the support truck was blocked to prevent any roll ahead. The Test Data Summary Sheets from the E-TECH report are enclosed for reference, as is a drawing of the test article.
You noted that there were no TMA design changes during the certification test program; the same design was used in every test. The report shows that there were no fragments or other debris from the TMA that showed potential for penetrating the occupant compartment of either the impacting vehicle or host truck, or of presenting an undue hazard to other traffic, pedestrians, or personnel in a work zone. The Vorteq TMA did not swing significantly into adjacent traffic lanes during any of the tests. No debris of either the impacting vehicle or TMA ended up forward of the tailgate of the host vehicle. We also noted that the impacted TMA is capable of being safely transported a short distance off the road essentially intact after all test impacts.
Based upon the successful completion of the aforementioned Report 350 tests, we agree that Energy’s Vorteq Trailer TMA meets the NCHRP Report 350 criteria for the specified mandatory Tests 3-50 and 3-51 as well as optional Tests 3-52 and 3-53. The TMA was also restrained from forward and lateral movement in all of these tests, thus there is no upper limit to the weight of the support vehicle to which the Vorteq Trailer TMA can be attached. The system, as described above, may be used on the National Highway System (NHS) when such use is acceptable to the contracting authority.
Please note also that the following provisions apply to FHWA letters of acceptance:
David A. Nicol, P.E.
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