September 5, 2003


Mr. Robert D. Slagter
ANRO Timber Products, Incorporated
7887 Ashwood Drive, SE
Ada, Michigan 49301

Dear Mr. Slagter:

In your May 23 letter to Mr. Richard Powers of my staff, you requested the Federal Highway Administration's (FHWA) acceptance of a recycled plastic block, called the Anro block, for use with strong steel-post w-beam guardrail on the National Highway System (NHS). Subsequently, you had the Anro block tested at the Midwest Roadside Safety Facility and sent us a copy of that agency's report, "Performance Analysis of the Anro Timber Products Recycled Plastic Spacer Block", dated August 25, 2003. Based on comparison bogey vehicle tests of a standard wood block and the Anro block, both mounted on W150 x 13.5 steel posts, the report concluded that there was no substantial difference in performance between the two offset blocks.

The Anro block is an injection-molded product composed of approximately 60 per cent recycled polyethylene (PE), 40 per cent polypropylene (PP), and a maximum of 2 per cent blowing agent. Each block is nominally 100-mm (4-inches) wide for 162 mm (6.38 inches), and then flares out to a post-side width of 150 mm (6 inches) over the last 41 mm (1.62 inches). A 108-mm x 10-mm (4.25-inch x 0.38-inch) routing on the backside fits over the steel post flange. The bolt hole dimensions are 0.875-inches in diameter at the rail side, tapering uniformly to a 0.742-inch diameter at the post side. These and other dimensions are shown on the enclosure.

After reviewing the test results, I consider the Anro block acceptable for use with strong post w-beam barrier on the NHS when it conforms to the dimensions, and is composed of the same materials, as noted above and as shown in the enclosure. Please note that the following provisions apply to this acceptance:

Sincerely yours,

(original signed by John R. Baxter)

John R. Baxter, P.E.
Director, Office of Safety Design
Office of Safety

2 Enclosures