Dear Mr. Burkett:

A recycled plastic offset block (called the P-Block) for use with strong steel post W-beam guardrail was accepted for use on National Highway System (NHS) on November 7, 2002, (Federal Highway Administration ((FHWA)) acceptance letter B-109). A similar design for use with round wood posts was accepted on August 29, 2003 (acceptance letter B-109A). Both letters were addressed to Mr. Daniel J. Mushett with Interstate Timber Products Company.

In your March 9, 2004, letter to Mr. Richard Powers of my staff, you advised him that you have purchased the rights to the P-Block from Interstate Timbers Products Company and have further modified its design. You indicated that your modified block is comprised of the same materials as the P-Block (approximately 50/50 blend of High Density Polyethylene and Low Density Polyethylene with a small amount of additives), but that the flared “wings” centered along the back edge of the block have been lengthened from their original 7 inches to 12 inches. The traffic face of the block remains approximately 4-inches wide and its effective depth remains at just under 8 inches. These details are shown on the enclosed drawing (Enclosure 1). You had this redesigned block crash tested at E-TECH Testing Services, Inc. in Rocklin, California, the results of which are contained in that agency’s March 2003 report entitled “NCHRP Report 350 Crash Test Results for the Burkett Molding P-Block Guardrail Blockout.” Enclosure 2 is the summary page from the report that shows the 2000P pickup truck was fully contained and smoothly redirected following an impact into a strong post W-beam guardrail installation in which the modified P-Block was used in lieu of standard routed timber blockouts.

I agree that the modified P-Block, as described above, is acceptable for use with strong post
W-beam guardrail installations on the NHS. Minor modifications to the dimensions of the
P-Block for use with Thrie-beam guardrail (longer block and wings) and with round wood posts (concave backside to match the posts) are also acceptable.

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

• This acceptance is limited to the crashworthiness characteristics of the offset block and does not cover its long-term durability.
• Any changes that may adversely influence the crashworthiness of the device will require a new acceptance letter.
• Should the FHWA discover that in-service performance reveals unacceptable safety problems, or that the device being marketed is significantly different from the version that was accepted, it reserves the right to modify or revoke its acceptance.
• You will be expected to certify to potential users that the blocks furnished have essentially the same chemical composition and geometry as that submitted for acceptance.
• To prevent misunderstanding by others, this letter of acceptance, designated as number B-109B shall not be reproduced except in full. This letter, and the documentation upon which this letter is based, is public information. All such letters and documentation may be reviewed at our office upon request.
• This acceptance letter shall not be construed as authorization or consent by the FHWA to use, manufacture, or sell any patented device for which the applicant is not the patent owner. The FHWA acceptance is limited to the crashworthiness characteristics of the candidate device, and this office is neither prepared nor required to resolve issues concerning patent law. Please note that the FHWA reserves the right to withdraw an acceptance letter if the applicant’s submission is later shown to misrepresent the issue, either intentionally or unintentionally, or contains errors of fact or omission.
• If your product is patented, it cannot be specified for use on Federal-aid projects, except exempt, non-NHS projects. Our regulations concerning proprietary products are contained in Title 23, Code of Federal Regulations, Section 635.411, a copy of which is Enclosure 3.

Sincerely yours,

(original signed by Hari Kalla)
for:
John R. Baxter Director, Office of Safety Design
Office of Safety

3 Enclosures

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