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FHWA Home / Safety / Roadway Departure / Safety Eligibility Letter

Safety Eligibility Letter CC-95C

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U.S. Department of Transportation
Federal Highway Administration

1200 New Jersey Ave. S.E.
Washington, D.C. 20590

August 17, 2011

In Reply Refer To: HSST/CC-95C

Mr. Felipe Almanza
Chief Design Engineer
TrafFix Devices, Inc.
160 Avenida La Pata
San Clemente, CA  92673

Dear Mr. Almanza:

This letter is in response to your request for the Federal Highway Administration (FHWA) acceptance of an alternative anchoring system for your Compressor Crash Cushion for use on the National Highway System (NHS).

Name of system: Compressor Crash Cushion
Type of system: Non-Gating Self-Restoring Narrow Crash Cushion/Impact Attenuator
Test Level: NCHRP Report 350 Test Level 3 (TL-3)
Testing conducted by: KARCO Engineering, LLC
Date of request: December 21, 2010
Date initially acknowledged: December 28, 2010
Task Force 13 designator: SCI28

You requested that we find an alternative anchoring system acceptable for use on the NHS under the provisions of the National Cooperative Highway Research Program (NCHRP) Report 350.

Requirements
Roadside safety devices should meet the guidelines contained in NCHRP Report 350. The FHWA memorandum "ACTION: Identifying Acceptable Highway Safety Features" of July 24, 1997, provides further guidance on crash testing requirements of longitudinal barriers and crash cushions.

Decision
The following device was found acceptable, with details provided below:

Description
The Compressor Crash Cushion was originally accepted for use on the NHS for one-way traffic applications in FHWA Product Acceptance Letter CC-95 on February 26, 2007 and for two-way traffic applications in Acceptance Letter CC-95A, dated December 23, 2009.  In both cases, the Compressor was mounted on a reinforced concrete pad using fourteen (14) anchor bolts for each of the crash tests conducted.  For the present request, the Compressor itself remained unchanged from the previously accepted design. In short, the TrafFix Devices Inc. Compressor is a re-directive, non-gating and self-restoring narrow crash cushion with a total length of  6.5 meters (255.25 inches).  Its effective length is  4.98 meters (196 inches). The Compressor measures 1.24 meters (48.66 inches) wide, and is 1.36 meters (53.5 inches) in height.  Its main components include: a steel mounting base, six plastic energy absorbing modules, and twelve steel fender panels.  The front and rear anchor plates remain unchanged from the previously accepted design, but eight (8) anchor clips have been added to each side of the base plate to accommodate the additional anchors needed to secure the Compressor to an asphalt pad.  Thirty (30) 7/8-inch-9TPI threaded anchor rods with an overall length of 406 millimeters (16 inches) were used.  These rods were set into 2.54 millimeters (1-inch) diameter holes drilled 355.6 millimeters (14 inches) deep through a 6-inch thick asphalt pad and into compacted sub base.  All bolts were secured with an epoxy adhesive.  The front and rear anchor rods are positioned in the same fourteen (14) locations as were the concrete anchor bolts used for Acceptance Letter CC-95 and CC-95A testing.  Design details for anchoring the Compressor to an asphalt pad are provided as enclosure to this correspondence.

Crash Testing
Since the basic design of the Compressor was unchanged from the previously accepted version, required testing for the new anchoring system is to determine the adverse affects of the crash performance of the unit.  After an initial consultation with FHWA, it was agreed that NCHRP Report 350 tests 3-33 and 3-38 were likely to place the greatest loadings on the new anchor design and that the remaining tests for a redirective crash cushion need not be rerun.

Test 3-33 required a 100 km/h impact by a 2000-kg pickup truck at 15 degrees on the nose of the crash cushion.  As reported in Karco Test Report Number TR-P30145-01-A, dated December 4, 2010, a 2042 kg (4502 lb) pickup truck impacted the Compressor at 101.4 km/h (63 mph) and at 14.8 degrees. Occupant Impact Velocity was 10.7 m/sec and the Ridedown Acceleration was 14.6 g's. Vehicular roll, pitch, and yaw were recorded as 43.9, 30.5, and 177.3 degrees, respectively. The truck came to rest 3.9 meters (12.8 feet) rearward and 8.4 meters (27.5 feet) to the left of the crash cushion.  The Karco report indicated that some repairs would need to be made to the Compressor to return it to its fully functional condition.

Test 3-38 also required a 100 km/h 2000-kg pickup truck test, but into the side of the Compressor at a 20-degree angle.  Karco Test Report Number TR-P30144-01-A, dated December 3, 2010, reported a 2029.5-kg (4473-lb) truck struck the crash cushion at 100.2 km/h (62.3 km/h) and 20.1 degrees.  Occupant Impact Velocity was 7.0 m/sec (lateral) and the Ridedown Acceleration was 12 g's. Vehicular roll, pitch and yaw were recorded as 15.7, 18.4, and 26.7 degrees, respectively.  The truck came to rest 61.5 m (201.8 ft) downstream and 21.3 m (69.9 ft) to the left of the Compressor.  After this test, the Compressor appeared to remain functional without requiring repairs.

Crash Test summaries are provided as enclosure to this correspondence.

Findings
The Compressor as described above and in Acceptance Letters CC-95 and CC-95A is acceptable for use on the NHS as a Self Restoring/Low Maintenance, Narrow Crash Cushion as a permanent or temporary attenuator when such use is acceptable to a highway agency.  It can be mounted on a concrete pad with fourteen (14) anchor bolts or on an asphalt pad using thirty (30) steel rod anchors.  The Compressor can be used in bi-directional traffic flow applications when used with Karco's tested transition design.

Therefore, the system described in the requests above and detailed in the enclosed drawings is
acceptable for use on the NHS under the range of conditions tested, when such use is acceptable
to a highway agency.

Please note the following standard provisions that apply to FHWA letters of acceptance:

The acceptance letter is limited to the crashworthiness characteristics of the candidate system, and the FHWA is neither prepared nor required to become involved in issues concerning patent law. Patent issues, if any, are to be resolved by the applicant.
 

Sincerely yours,

/* Signature of Michael S. Griffith */
Michael S. Griffith
Director, Office of Safety Technologies
Office of Safety

Enclosures

Page last modified on January 17, 2013.
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