September 18, 2002
Mr. Chad Heimbecker
Director, Product Development
Bryson Products, Inc.
224 Nazareth Pike, Suite 22
Bethlehem, PA 18020
Dear Mr. Heimbecker:
In your July 25 letter to Mr. Richard Powers of my staff, you requested formal acceptance of a revised plastic guardrail offset block named RE-BLOCK:IV and provided a copy of a Texas Transportation Institute report dated July 19, 2002, and entitled "Pendulum Testing and Evaluation of the Central Fabricator's Guardrail Blockout."
The RE-BLOCK:IV, as shown in the enclosure, is a hollow 4 inch x 8 inch block with three horizontal stabilizer bars and a depth of 14 inches for use with W-beam and 21-5/8 inches for use with Thrie-beam. Its material composition is similar to the original RE-BLOCK, using an average blend of 50 per cent HDPE and 50 per cent LDPE. Additionally, successful pendulum tests were conducted on a block made with 100 per cent HDPE and one made with 80 per cent HDPE and 20 per cent cross-linked HDPE/PP. All of these formulations include approximately 1 per cent carbon black to reduce the effects of UV degradation.
Based on staff review of the information you provided, the appropriate-sized RE-BLOCK:IV may be used with wood or steel strong-post W-beam and Thrie-beam guardrail systems on the National Highway System (NHS) when such use is acceptable to the contracting agency.
Please note the following provisions that apply to all FHWA letters of acceptance for synthetic offset blocks:
Please contact Mr. Powers at (202) 366-1320 should you have questions.
(original signed by Carol H. Jacoby)
Carol H. Jacoby, P.E.
Director, Office of Safety Design