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FHWA Home / Safety / Roadway Departure / Safety Eligibility Letter

Safety Eligibility Letter CC-95A

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U.S. Department of Transportation
Federal Highway Administration

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

December 23, 2009

In Reply Refer To:

Mr. Geoff Maus
TrafFix Devices, Inc.
160 Ave. La Plata
San Clemente, CA 92673

Dear Mr. Maus:

This letter is in response to your request for the Federal Highway Administration (FHWA) acceptance of a roadside safety device for use on the National Highway System (NHS).

Name of device: TrafFix Devices, Inc., Compressor
Type of device: Crash Cushion/Impact Attenuator
Test Level: NCHRP Report 350 Test Level 3
Testing conducted by: Karco Engineering
Date of request: May 21, 2009
Date completed package received by FHWA: November 3, 2009

You requested that we find this device 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.”

Roadside safety devices should meet the guidelines contained in the NCHRP Report 350. The FHWA Memorandum titled “ACTION: Identifying Acceptable Highway Safety Features” of July 25, 1997, provides further guidance on crash testing requirements of longitudinal barriers.

The TrafFix Devices Inc. Compressor is a re-directive, non-gating, bi-directional use crash cushion with overall length of 255.25 inches (6.5 m). Its effective length is 196 inches (4.98 m). The Compressor measures 48.66 inches (1.24 m) wide, and is 53.5 inches (1.36 m) in height.

The main components include: a steel structural Uni-Base, six plastic energy attenuating module elements, twelve steel fender panels, and an optional rear transition kit. The Uni-base is comprised of a dovetail rail which allows the modules to slide as they compress during an impact. The dovetail retains the six modules on the track, preventing lateral or vertical movement upon impact. Attached to the Compressor Module sides are twelve fender panels connected to the lower edge clips of each module. Attached to the rear fender panel’s trailing edge is the transition kit, designed to redirect an impacting vehicle approaching in a reverse direction.

The transition kit consists of four main components: a shorter fender panel, lateral rear support frame, a standard thrie beam panel section, and an end shoe. The short fender panel is the same profile design as the fender panels used on the Compressor sides. The lateral support frame is made of steel angle and plate. The lateral frame provides structural support within the 38-inch (965-mm) gap region when impacted in the reverse direction and re-directs the impacting vehicles. The standard thrie beam section is a transition panel with a shoe end attached. Horizontal mounting bolts are used to anchor the transition shoe to the CMB, using 1 inch-8 insert bolts along the shoe flange trailing edge.

The transition kit attaches directly to the existing Compressor fender panels by bolting to the short fender panels and adding a standard thrie beam at a 10 degree position to the CMB. The lateral support frame bolts directly to the existing concrete mounting anchor bolts. The transition includes two wood offset blocks between the transition rail and the face of the concrete barrier. The blocks may be cut as needed for transitioning to safety-shaped, constant slope, or vertical barriers.

Fourteen 3/4-inch (19-mm) concrete anchor bolts are used to secure the Compressor to the concrete test pad. The anchor bolts are 5 to 6 inches (127 mm to 152.4 mm) of ACME thread below grade with a 1-inch (25.4-mm) shoulder and 3/4 inches (19 mm)-10 x 1-1/2" (38.1 mm) above grade to secure the base to the studs. A high strength two part catalyzed resin anchoring material is used to secure the anchor bolts below grade.

Crash Testing
The TrafFix Devices Inc. Compressor was initially found acceptable in FHWA Acceptance Letter CC-95, dated February 26, 2007. This letter indicated that the reverse direction test, NCHRP Report 350 Test 3-39, needed to be run in order for the Compressor to be considered for bi-directional use. Your present request is based on the Test 3-39 you conducted on March 27, 2009, a summary of which is enclosed for reference. All occupant risk and vehicle trajectory results were satisfactory.

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

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


Sincerely yours,

Signature of David A. Nicol

David A. Nicol
Director, Office of Safety Design
Office of Safety


Page last modified on January 17, 2013.
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