Federal Highway Administration
400 Seventh St., S.W.
March 3, 2008
In Reply Refer To: HSSD/CC-65C
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 October 12, 2007, requesting Federal Highway Administration (FHWA) acceptance of your company’s Scorpion Test Level 3 (TL-3) Trailer Attenuator (TA) for use on the National Highway System (NHS). Accompanying your letter was a report of crash testing conducted by KARCO Engineering and DVD video of the tests. You requested that we find the TA acceptable for use when attached to vehicles of any mass above 10,000 kg (22,046 pounds) 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.”
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 description of the device follows:
The TrafFix Devices Inc. Trailer Attenuator is a truck attached crash cushion which attaches directly to a host vehicle’s pintle hook from a standard lunette eye on the attenuator. The overall dimensions are 36 inches x 96 inches x 209 inches (0.91 meters x 2.44 meters x 5.3 meters) and weighs approximately 1,900 pounds (860 kilograms) when fully assembled.
The main components are: a steel tongue section, an aluminum strut section, and a rear cartridge section with axle and tire assembly.
The steel tongue section is the attachment point for the trailer to the host vehicle and incorporates an anti-rotation feature that is activated in the event of an impact. The impact energy shears a steel shear pin, allowing the tongue’s inner and outer tubes to slide forward relative to each other. Anti-rotation supports come into contact with the support truck’s frame plate. This contact acts as a positive stop to the trailer’s rotation and can induce a reactive force counter to rotation, which prevents the attenuator from rotating. The complete tongue assembly including the pintle eye is 58 inches (1.47 meters) long, with a maximum width of 74 inches (1.88 meters). The complete tongue assembly weighs approximately 639 pounds (290 kilograms).
The aluminum strut section is comprised of a structural energy absorbing curved aluminum tube framework, and a single engineered aluminum crush module. The strut section is the same as that used in the NCHRP-350 approved TrafFix Devices Inc., Scorpion Truck Mounted Attenuator (TMA). The strut section is 96 inches (2.44 meters) in width and 57.5 inches
(1.46 meters) in length.
The aluminum cartridge section is comprised of a structural energy absorbing curved aluminum tube framework, with three engineered aluminum crush modules. Located at the cartridge is a steel diaphragm frame which provides a stable platform for the axle and wheel assembly. The width is a maximum of 96 inches (2.44 meters) at the wheels and fenders and the length is 24.625 inches (0.63 meters). The cartridge section is the same cartridge section that is currently used in the NCHRP-350 accepted TrafFix Devices Inc., Scorpion TMA. The cartridge section is 96 inches (2.44 meters) in width and 96 inches (2.44 meters) in length.
The Scorpion TA had been tested and found acceptable in FHWA acceptance letter CC-65B dated March 16, 2007. One additional full-scale crash test was conducted. The test was designated 3-51M because the test used a support vehicle that was blocked and prevented from moving. A drawing of the trailer attenuator and a copy of the Test Data Summary Sheet are enclosed for reference.
The test vehicle impacted the device and came to a controlled stop with virtually no rotation. The occupant impact forces were within the limits specified by NCHRP Report 350. The results of the testing met FHWA requirements and, therefore, the Scorpion TA described above and detailed in the enclosed drawing is acceptable for use on NHS under the range of conditions tested, when permitted by a highway agency. Because the support vehicle was blocked to prevent roll-ahead, the Scorpion TA may be used with support vehicles of any mass greater than 10,000 kg (22,000 pounds). As the TL-3 Scorpion TA was also tested using a 4500 kg (9920 pounds) support vehicle, we concur that the TL-3 Scorpion TA may be used on any vehicle with a mass greater than 4500 kg with no upper weight limit.
Please note the following standard provisions that apply to the FHWA letters of acceptance:
For: David A. Nicol, P.E.
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