Federal Highway Administration
400 Seventh St., S.W.
March 3, 2008
In Reply Refer To: HSSD/CC-65D
Mr. Felipe Almanza
Technical Engineering Director
Mr. Jan D. Miller
Business Development Manager
TrafFix Devices, Inc.
220 Calle Pintoresco
San Clemente, CA 92672
Dear Messrs. Almanza and Miller:
Thank you for your letter of August 2, 2007, requesting Federal Highway Administration (FHWA) acceptance of your company’s Test Level 2 (TL-2) Scorpion Trailer Attenuator (TA) for use on the National Highway System (NHS) based on prior testing of other Scorpion Attenuators. Accompanying your letter were reports of crash testing conducted by KARCO Engineering and DVD video of those earlier tests of the TL-2 Scorpion Truck Mounted Attenuator (TMA) and the TL-3 Scorpion TA. You requested that we find the Scorpion TL-2 TA acceptable for use on the NHS under the provisions of National Cooperative Highway Research Program (NCHRP) Report 350 “Recommended Procedures for the Safety Performance Evaluation of Highway Features.” In a January 21, 2008, e-mail message to Mr. Nicholas Artimovich of my staff you agreed to the conditional acceptance conditions noted below.
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.”
A brief description of the device follows:
The TL-2 TA design is shown in the enclosure and consists of a 255-kg (562-pound) cartridge section consisting of aluminum honeycomb inside three separate aluminum boxes. These three energy-absorbing units are supported by and within a 114-mm (4.5-inch) diameter tubular aluminum frame. This design is 3800 mm (149 5/8 inches) long and its total weight, including the mounting hardware is 629 kg (1386 pounds).
Two modifications were made to the Scorpion TL-2 TMA to produce the TL-2 TA design: (1) a rear mounted axle with tire assembly attached to a steel diaphragm at the rear cartridge, and (2) the steel tongue section that provides the trailer attachment point which incorporates an anti-rotation feature that is activated in the event of an impact. These modifications are displayed in the enclosed drawings and are identical to the modifications made to the TL-3 TMA when a trailer version was made of that TMA. When impacted, the steel tongue is specifically designed to prevent the Attenuator Trailer from rotating about the pintle hook and the rear of the host vehicle by engaging the Telescoping Anti-Rotation System (TARS). The TARS must be aligned with the frame plate of the host vehicle to engage the anti-rotational arms and its bumper must be able to resist the anticipated TL-3 design impact loads to ensure optimal attenuator crash performance.
No separate testing was done on the Scorpion TL-2 TA. Rather, you rely on prior testing of the TL-2 TMA and TL-3 TA.
The NCHRP Report 350 Tests 2-50 and 2-51 (head-on 820C and 2000P, respectively) were conducted on the Scorpion TL-2 TMA and documented in FHWA acceptance letter CC-65 dated July 14, 2000. The TL-3 TMA was also documented in this letter.
The NCHRP Report 350 Tests 3-50, 3-51, 3-52, and 3-53 (head on, angle, and offset impacts) were conducted on the TL-3 TA and documented in FHWA acceptance letter CC-65B dated
March 16, 2007.
You contend that the TL-2 TMA tests prove the concept that the short Scorpion can decelerate the impacting vehicle while meeting NCHRP Report 350 evaluation criteria, and that the TL-3 tests prove that the addition of the wheel assembly and the anti-rotation connection do not compromise the performance of the device.
While we are usually open to accepting variations to tested safety hardware based on “worst-case scenario” analysis, we find that TMA trailers may not be as “predictable” as some other devices. We concur that prior testing of the Scorpion attenuators noted above tend to indicate that the TL-2 trailer will perform in an acceptable manner, and grant conditional acceptance for use on the NHS. You shall monitor the in-service performance of TL-2 TA units sold, and report on their performance in two years time (including impacts during 2008 and 2009). At that time FHWA will reassess our conditional acceptance.
The results of prior testing met the FHWA requirements and we concur that they indicate likely acceptable performance of the TL-2 TA. Therefore, the Scorpion TL-2 TA described above and illustrated in the enclosed drawing is acceptable for use on the NHS under the range of conditions that other Scorpion attenuators were tested, when permitted by the highway agency, subject to our condition regarding a two-year in-service performance evaluation.
Please note the following standard provisions that apply to the FHWA letters of acceptance:
For: David A. Nicol, P.E.
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