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August 24, 2004

Refer to: HSA-10/B-128

Mr. Byron Berger
Acting Chief
Roadside Safety Technology Branch
Materials Engineering and Testing Services
5900 Folsom Boulevard
Sacramento, California 95819-4612

Dear Mr. Berger:

In Mr. Sudhakar Vatti's July 12 letter, he requested formal acceptance by the Federal Highway Administration of a see-through, combination steel post and beam bridge rail called the California ST-20S. This design, shown in Enclosure 1, was based on a previously accepted Wyoming DOT design for a test level 4 (TL-4) bridge rail and a modified version of your crash-tested ST-20 design. In your test, there was some hood snagging observed with the pickup truck, so you increased the rail face to post face distance in the ST-20S to reduce the likelihood of this occurrence. The final ST-20S design consists of four horizontal box-beam rail elements, the top and bottom ones being TS 203 x 76 x 7.9 structural tubes, and the middle two being TS 203 x 102 x 7.9 tubes. The summary results of the test you ran are shown in Enclosure 2.

Since your design uses thicker steel plate posts, has a greater rail offset then the Wyoming TL-4 rail, and has a lesser opening between the lower rail elements, you did not believe it necessary to conduct the small car test. Similarly, because the ST-20S is 1185-mm high (excluding the additional 187-mm tall top bicycle rail) versus the 830-mm high Wyoming design, you did not conduct the single-unit truck test. I concur that both of these tests can be waived based on the performance of the Wyoming design and on the differences between the two designs.

Therefore, the ST-20S design may be considered an NCHRP Report 350 bridge rail at TL-4 and used on the National Highway System when selected by the appropriate transportation authority. I assume that anyone needing detailed drawings and material specifications can obtain this information directly from your office.


Sincerely yours,

(Original Signed By R. Powers)
John R. Baxter, P.E.
Director, Office of Safety Design
Office of Safety

2 Enclosures

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