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FHWA Home / Safety / Roadway Departure / Safety Eligibility Letter

Safety Eligibility Letter B-174

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U.S. Department of Transportation
Federal Highway Administration

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

April 16, 2008

In Reply Refer To: HSSD/B-174

Mr. Michael J. Burkett
President
Monroeville Industrial Molding
75 Ontario Street
Norwalk, OH 44857

Dear Mr. Burkett:

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: Monroeville 8 inch Composite Offset Block
Monroeville 12 inch MGS Composite Offset Block
Type of device: Blockouts for W-beam barrier systems
Test Level: NCHRP Report 350 TL-3
Testing conducted by: E-Tech Testing Services
Date of request: January 30, 2008

You requested that we find these devices 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, "Recommended Procedures for the Safety Performance Evaluation of Highway Features". FHWA Memorandum “ACTION: Identifying Acceptable Highway Safety Features” of July 25, 1997, provides further guidance on crash testing requirements of longitudinal barriers.

Description
Both the standard w-beam guardrail, normally mounted at 27 ¾ inches to the top, and the Midwest Guardrail System (MGS) barrier, normally mounted at 31 inches to the top, require offset blocks to reduce the impact of vehicle wheels snagging on the posts. Burkett Molding, Inc., received FHWA acceptance letter B-109B, dated March 17, 2004, for an 8-inch deep offset block. As your company, Monroeville Industrial Molding now owns the rights to the Burkett offset blocks you have asked for a letter in your company’s name. You also had an additional test conducted using a 12-inch deep version of this offset block for use on the MGS. Your present request includes acceptance of the larger offset block.

The Monroeville offset blocks were installed in a 175-foot long test section of MGS w-beam guardrail. The line posts were 6 inches deep x 4 inches wide x 72 inches long galvanized steel and embedded to 40 inches. The line posts supported a length of need section of AASHTO standard RWM03a (12 ga) w-beam guardrail. The rail sections are spliced together with (8) AASHTO standard FBB01 guardrail bolts and recessed nuts such that the splices are positioned mid-span between posts. The 12-inch deep x 4-inch wide x 14-inch high “Monroeville P” plastic blockout is positioned between the post and rail and secured in place with a single 0.625-inch diameter FBC16 carriage bolt installed in the upstream bolt hole position.

Crash Testing
The test of the MGS barrier with the 12-inch Monroeville offset blocks is summarized in the test data sheet, enclosed for reference. The 2000P vehicle was contained by the barrier and remained in contact with it, experiencing a yaw of approximately 70 degrees. All occupant risk values met NCHRP Report 350 criteria. The Midwest Roadside Safety Facility, developer of the MGS barrier, concurred in the positive evaluation of the test using the Monroeville offset blocks.

Findings
The MGS barrier using the 12-inch Monroeville Offset Blocks described in the above and detailed in the enclosed drawing is acceptable for use on the NHS under the range of conditions tested, when proposed by a State.

Also, the 8-inch offset blocks developed by Burkett Molding and manufactured by Monroeville Industrial Molding discussed in FHWA acceptance letter B-109B continue to be acceptable for use.

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

 

Sincerely yours,

George E. Rice, Jr.

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

2 Enclosures


Illustration d-2. Monroeville 12” P Block (1 of 1)

Page last modified on June 24, 2011.
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