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FHWA Home / Safety / Roadway Departure / Safety Eligibility Letter

Safety Eligibility Letter CC-57C

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U.S. Department of Transportation
Federal Highway Administration

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

November 14, 2008

In Reply Refer To: HSSD/CC-57C

Mr. Barry D. Stephens, P.E.
Sr. Vice President Engineering
Energy Absorption Systems, Inc.
3617 Cincinnati Avenue
Rocklin, CA 95678

Dear Mr. Stephens:

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

Name of device: 5-Bay QuadGuard® Elite
Type of device: Impact Attenuator
Test Level: NCHRP Report 350 TL-2
Testing conducted by: E-TECH Testing Services, Inc.
Date of request: April 28, 2008

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.”

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

Description
The redirective, non-gating crash cushion called the QuadGuard® Elite with a reduced length requirement of 5 bays is identical to the previously accepted 7-bay unit tested at test level 2 (TL-2) and accepted for use on June 17, 1999, in the FHWA Acceptance Letter C-57A, with the exception of 2 bays being removed from the rear of the system. The features of the 5-bay QuadGuard® Elite system are depicted in the enclosed drawing. The QuadGuard® Elite 5-bay system has an overall length of 5.45 m (17 feet, 10.5 inches), and can be configured with backup widths of 610 mm (24 inches), 762 mm (30 inches), 914 mm (36 inches), 1753 mm (69 inches), and 2286 mm (90 inches). The system consists of energy absorbing plastic cylinders surrounded

by a framework of steel Quad-Beam® guardrail that can telescope rearward during head-on impacts. There are no cylinders in the first two bays. The system has a center monorail that will resist lateral movement during side angle impacts and a back up structure that will resist movement during head-on impacts.

Crash Testing
The original 7-bay test data of NCHRP 350 Test 2-31 demonstrated that the 2000P vehicle impacting at 0 degree and a nominal speed of 70 km/h (43.5 mph) resulted in ridedown g’s of 9.3 and Occupant Impact Velocity (∆V) of 6.5 m/s. An engineering review of this previous data indicated excess capacity in the device and prompted a crash test to be done after removing Bays 6 and 7. The results were as follows: Impact speed: 70.0 km/h (43.5 mph), ridedown of 12.0 g’s, and ∆V of 7.7 m/s.

Due to the elimination of bays at the rear of the system we concur that the test performed provides adequate capacity for head-on impacts. Furthermore, the small car 820C vehicle did not collapse beyond bay 5 in the original 7-bay testing. Therefore we agree that due to the front of the system not being changed the 820C vehicle crash characteristics should not be changed. Based upon the multiple redirective test impacts into the QuadGuard® and the basic structure of the reduced 5-bay Elite being unchanged, redirective tests are not required.

Findings
The QuadGuard® Elite 5-bay system meets the evaluation criteria for an NCHRP Report 350 redirective, non-gating crash cushion at TL-2 impact conditions and is acceptable for use on the NHS when such use is acceptable to the contracting authority.

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

 

Sincerely yours,

Signature of George E. Rice, Jr.
for David A. Nicol
Director, Office of Safety Design
Office of Safety

Enclosures

Page last modified on January 17, 2013.
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