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FHWA Home / Safety / Roadway Departure / Safety Eligibility Letter

Safety Eligibility Letter B-231

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U.S. Department of Transportation
Federal Highway Administration

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

July 10, 2014 HAND CARRIED BY WL

In Reply Refer To:
HSST/B-231 Revised

Scott Rosenbaugh
Research Associate Engineer
Midwest Roadside Safety Facility UNL
2200 Vine Street
130 Whittier Building
Lincoln NE,  68583-0853

Dear Mr. Rosenbaugh:

This letter is in response to your request for revisions to the existing eligibility letter B-231 dated January 27, 2012, and for the Federal Highway Administration (FHWA) to review a roadside safety system for eligibility for reimbursement under the Federal-aid highway program.

Name of system: Transition from steel post MGS to thrie-beam approach
Type of system: W-beam to thrie-beam stiffness transition
Test Level: MASH Test Level 3
Testing conducted by: Midwest Roadside Safety Facility
Task Force 13 Designator: STG03a
Date of request: June 28, 2011
Date of revision request: April 10, 2014
Date of completed package: June 28, 2011

Decision:
The following device is eligible, with details provided in your letter of June 28, 2011, which is enclosed as an integral part of this finding:

Based on a review of submitted revisions to existing eligibility letter B-231 dated January 27, 2012 and to crash test results submitted by the manufacturer certifying the device described herein meets the crashworthiness criteria of the American Association of State Highway and Transportation Officials' Manual for Assessing Safety Hardware (MASH), the device is eligible for reimbursement under the Federal-aid highway program. Eligibility for reimbursement under the Federal-aid highway program does not establish approval or endorsement by the FHWA for any particular purpose or use.

The FHWA, the Department of Transportation, and the United States Government do not endorse products or services and the issuance of a reimbursement eligibility letter is not an endorsement of any product or service.

Requirements
Roadside safety devices should meet the guidelines contained in the MASH.

Description and Crash Testing
Guardrail to bridgerail transitions are designed to gradually increase the stiffness of the semi-rigid w-beam barrier until connected to the rigid bridge railing. Typically, a single critical impact point (CIP) has been evaluated with full-scale crash testing. That CIP is usually located at the point where we anticipate the greatest likelihood of vehicle snagging or pocketing near the beginning of the rigid bridge railing. Because the stiffness of the barrier transition hardware needed to adequately shield the end of the rigid bridge railing is substantial, there is also reason to determine if the change in stiffness between the w-beam guardrail and the transition design itself is safe. A transition from the MGS with 12-inch deep blockout to a stiffened thrie-beam rail using an asymmetrical "Y" transition piece was evaluated in your crash testing. The enclosed letter describes the transition design and the two crash tests conducted.

Also enclosed are the test data summary sheets and drawings of the transitions.

Findings
Therefore, the system described and detailed in the attached letter, including the various attachment alternatives, is eligible for reimbursement and may be installed under the range of conditions tested.

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

 

Sincerely yours,

/* Signature of Michael S. Griffith */

Michael S. Griffith
Director, Office of Safety Technologies
Office of Safety

Enclosures

Page last modified on February 22, 2017
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Federal Highway Administration | 1200 New Jersey Avenue, SE | Washington, DC 20590 | 202-366-4000