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FHWA Home / Safety / Roadway Departure / Safety Eligibility Letter

Safety Eligibility Letter CC-35I

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U.S. Department of Transportation
Federal Highway Administration

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

March 20, 2009

In Reply Refer To: HSSD/CC-35I

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 the Federal Highway Administration (FHWA) acceptance of a roadside safety device for use on the National Highway System (NHS).

Name of device: 5-bay QuadGuard II
5-bay QuadGuard II Wide
2-bay QuadGuard II
Type of device: Impact Attenuators
Test Level: NCHRP Report 350 Test Levels 2 and 3
Testing conducted by: E-Tech Testing Services, Inc.
Date of request: December 8, 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 “Identifying Acceptable Highway Safety Features” of July 25, 1997, provides further guidance on crash testing requirements of longitudinal barriers.

Description
The QuadGuard® II is a redirective, non-gating crash cushion with a reduced length of 5 bays that is otherwise identical to the previously accepted Test Level 3 (TL-3) 6-bay unit (see FHWA Acceptance Letter CC-35, dated June 21, 1996). The difference is that one bay is removed from the rear of the system and a new sheet metal front nose is used. Likewise, the QuadGuard® II with a reduced length of 2 bays is identical to the previously accepted TL-2 3-bay unit (ref. CC-35C, dated June 17, 1999) with the exception of one of the rear bays being removed plus a new sheet metal front nose.

Features of the 5-bay QuadGuard® II systems (narrow and wide) as well as the 2-bay QuadGuard® II narrow system are depicted in the enclosed drawings for reference. The QuadGuard® II 5-bay narrow system has an overall length of 5830 mm (19’ 1”) 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 2-bay QuadGuard® II system has an overall length of 3080 mm (10’ 1”) and can be configured with a backup width of 610 mm (24 inches). The system consists of energy absorbing cartridges surrounded by a framework of steel Quad-Beam® guardrail that can telescope rearward during head-on impacts. 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. Simply removing a rear Bay from an existing 6-Bay or 3-Bay system will not be adequate to meet TL-3 and TL-2 impact speeds, respectively. As noted in your report, the QuadGuard II system requires an upgraded nose assembly.

Crash Testing
The original 6-bay test data of NCHRP 350 Test 3-31 and 3-32 demonstrated that the 2000P vehicle impacting at 0 degree and a nominal speed of 100km/h (63 mph) resulted in a ridedown g’s of -14.52 and Occupant Impact Velocity (ΔV) of 10.55 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 bay 6. The NCHRP 350 Tests 3-31 and 3-32 were conducted and the results are as follows:

Narrow System 610mm (24 inches) width:
Test 3-31: Impact speed: 101.1 km/h, ridedown of -17.3 g’s, and ΔV 9.6 m/s.
Test 3-32: Impact speed: 98.3 km/h, ridedown of -17.4 g’s, and ΔV 12.4 m/s.

Wide System 2286mm (90 inches) width:
Test 3-31: Impact speed: 99.7 km/h, ridedown of -17.0 g’s, and ΔV 10.0 m/s.
Test 3-32: Impact speed: 97.7 km/h, ridedown of -17.4 g’s, and ΔV 11.7 m/s.

Similarly the 3-bay narrow system test data demonstrated that the 2000P vehicle impacting at 0 degree and a nominal speed of 70km/h (43.5 mph) resulted in a ridedown g’s of -19.57 and Occupant Impact Velocity (ΔV) of 8.89. Again an engineering review indicated excess capacity in the device and prompted the following crash tests with results as follows:

Test 2-31: Impact speed: 68.3 km/h, ridedown of -19.4 g’s, and ΔV 10.7 m/s.
Test 2-32: Impact speed: 67.7 km/h, ridedown of -17.8 g’s, and ΔV 10.8 m/s.

Due to the elimination of one bay at the rear of each system we concur that the tests performed provide adequate capacity of head-on impacts for all widths of TL-3 5-bay QuadGuard® II systems. In addition we also concur that the tests performed on the TL-2 2-bay QuadGuard® II system provide adequate capacity for head-on impacts for the 610mm (24 inches) width system. We agree that the front of the system was adequately tested for the 820C vehicle crash characteristics. Based upon the multiple redirective test impacts into the QuadGuard® and the basic structure of the reduced 5-bay and 2-bay QuadGuard® II being unchanged, redirective tests are not required.

Findings
The QuadGuard® II 5-bay and 2-bay systems meet the evaluation criteria for NCHRP Report 350 redirective, non-gating crash cushion at TL-3 and TL-2 impact conditions respectively and are acceptable for use on the NHS when such use is acceptable to the contracting authority. It’s further acknowledged that the QuadGuard® II can be installed with existing QuadGuard® Transition hardware (Reference CC-35B, dated October 17, 1996.)

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

 

Sincerely yours,

Signature of David A. Nicol

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

Enclosures

Page last modified on January 17, 2013.
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