U.S. Department of Transportation
Federal Highway Administration
1200 New Jersey Avenue, SE
Washington, DC 20590
202-366-4000


Skip to content
FacebookYouTubeTwitterFlickrLinkedIn

Safety

eSubscribe
eSubscribe Envelope

FHWA Home / Safety / Roadway Departure / Safety Eligibility Letter

Safety Eligibility Letter CC-109A

Download Version
PDF [60 KB]

DOT logo
U.S. Department of Transportation
Federal Highway Administration

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

August 19, 2011

In Reply Refer To: HSST/CC-109A

Mr. Gerrit A. Dyke, P.E.
Barrier Systems, Inc.
3333 Vaca Valley Parkway, Suite 800
Vacaville, CA 95688

Dear Mr. Dyke:

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

Name of system: X-TENuator Wide (X-TEN Wide)
Type of system: Variable width Redirective Non-Gating Crash Cushion
Test Level: NCHRP Report 350 TL-3
Testing conducted by: Safe Technologies Inc.
Date of request: December 27, 2010
Request Initially acknowledged: January 4, 2011
Task Force 13 designator: SCI23b

You requested that we find alternative widths to your narrow X-TEN crash cushion acceptable for use on the NHS under the provisions of the National Cooperative Highway Research Program (NCHRP) Report 350 "Recommended Procedures for the Safety Performance Evaluation of Highway Features."  The original design described in FHWA Acceptance letter CC-109 was a parallel-sided attenuator 36-inches (926-millimeters) wide.

Requirements
Roadside safety devices should meet the guidelines contained in the NCHRP Report 350 if tested prior to December 31, 2010 or the American Association of State Highway and Transportation Officials' Manual for Assessing Safety Hardware (MASH) if tested after that date.  The FHWA Memorandum "Identifying Acceptable Highway Safety Features" of July 25, 1997 provides further guidance on crash testing requirements of longitudinal barriers.

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

Description
The X-TEN system is a redirective, non-gating crash cushion designed to decelerate an errant vehicle to a safe stop when struck end-on or redirect an errant vehicle away from roadside or median hazards when impacted along either side.  The system is comprised of an energy absorbing nose bracket and cover, dual X-Tension impact heads and cables, front cable anchors, W-Beam side panels, specially designed posts and post braces and a separate rigid backstop. Standard W-Beam offset blocks are used to attach the side panels to the posts.  Enclosure 1 shows both an alternate new narrow design and the new wide design.

The X-TEN Wide design differs from the original design in three significant ways:

Crash Testing
The X-TEN Wide crash cushion was successfully tested at its maximum width of 60 inches (1500 millimeters) under NCHRP Report 350 test designations 3-31, 3-32, 3-37, and 3-38 by Safe Technologies Inc. Test 3-31 was also conducted on the 36-inch (915-millimeter) narrow design using double posts.  In tests 3-31(narrow design), 3-32, and 3-38, the X-TEN system was attached to a 75-millimeter (3-inch) thick Asphalt Concrete (AC) pad over 300 millimeters (12 inches) of a dense graded aggregate with sixty-eight (68) 20-millimeter (3/4-inch) long all thread studs embedded 400 millimeters(16 inches) and epoxied in place.  In tests 3-31 (wide design) and  test 3-37, the X-TEN Wide design was attached to a 250-millimeter (10-inch) thick Portland Cement Concrete (PCC) pad with fifty-two (52) 20-millimeter (3/4-inch) long all thread studs embedded 150 millimeters (6 inches) and epoxied in place.  This crash cushion can also be used on a 200-millimeter (8-inch) thick unreinforced or a 150-millimeter (6-inch) thick reinforced PCC pad.  You will be expected to provide users with concrete specifications and anchor designs for these applications.

Enclosures 6 through 10 summarize the results of the tests that were run.

Findings
The tests you ran conformed to the matrix agreed to beforehand by members of my staff, with slight modifications in scope based on your decision to limit development to a 60-inch (1500 millimeter) wide unit.  Each test met the appropriate Report 350 evaluation criteria.  In your letter, you have requested FHWA acceptance of the following:

Based on our review of the submitted information, including test reports, the X-TEN Wide system described 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:

 

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.
Safe Roads for a Safer Future - Investment in roadway safety saves lives
Federal Highway Administration | 1200 New Jersey Avenue, SE | Washington, DC 20590 | 202-366-4000