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FHWA Home / Safety / Roadway Departure / Safety Eligibility Letter

Safety Eligibility Letter B-195

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U.S. Department of Transportation
Federal Highway Administration

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

September 18, 2009

In Reply Refer To: HSSD/B-195

Mr. Barry D. Stephens
Sr. Vice President Engineering
Energy Absorption Systems, Inc.
3617 Cincinnati Avenue
Rocklin, CA 95765

Dear Mr. Stephens:

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:SSG™-200 (also called the SS K-12 Soft StopĀ®) Manufacturer: Energy Absorption Systems, Inc. (EASI)
Type of system:Security Barrier
Test Level:NCHRP Report 350 TL-2
Testing conducted by:E-TECH Testing Services
Date of request:April 30, 2009

You requested that we find this system 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.”

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

Description
The SSG™-200 Security Barrier is designed to manage the ingress and egress of vehicular traffic through secured areas. It is composed of two sections or halves that are joined at the centerline of the system. As the vehicle impacts the barrier, it engages sets of round tubes which get reshaped by sets of “shapers”. This reshaping of the round tubes dissipates kinetic energy in a controlled fashion and vehicles are brought to controlled stops. The SSG™-200 also includes housings containing electro-mechanical components that lower and raise the barrier. The overall width of the barrier, not including the lifting mechanism, is 4.77 m (15.7 ft). The thickness of the barrier is 147 mm (5.8 in) and the height of the barrier is 686 mm (27 in). The width of the system, including the lifting mechanism and covers, is 5.90 m (23.2 ft). The length of the barrier’s foundation is 3.66 m (12.0 ft).

Crash Testing
Successful full-scale crash tests, NCHRP Report 350 Tests 2-30 and 2-31, were conducted on the SSG™-200 Security Barrier as required per NCHRP Report 350. It should be noted that performance improvements were made during the course of development and these are summarized in the document you provided, “Engineering Summary of the SSG™-200”. To verify that these improvements had no negative effect on the overall system performance, the worst case test, NCHRP Report 350 test 2-31, was repeated. In each test, the barrier extended smoothly and brought the impact vehicle to rest in a controlled manner. After each test, the foundations and mounting stanchions were completely reusable. Only the expended barriers required replacement.

NCHRP 350 Test 2-31 (2000P/70KPH/0 deg) resulted in a longitudinal ridedown acceleration of -15.9 G and a longitudinal Delta-V of 7.4 m/s. Test 2-30 (820C/70KPH/0 deg) resulted in a longitudinal ride down acceleration of -12.4 G and a longitudinal Delta-V of 8.7 m/s. You also noted that there were no fragments or other debris from the security barrier that showed potential for penetrating the occupant compartments of either the impacting vehicles or that would present an undue hazard to other traffic or pedestrians.

Findings
Therefore, the 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 David A. Nicol

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

Enclosures

Page last modified on June 24, 2011.
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