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Safety Eligibility Letter B-45A

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U.S. Department of Transportation
Federal Highway Administration

400 Seventh St., S.W.
Washington, D.C. 20590

March 6, 1998

Refer to: HNG-14

Mr. Rich Peter
Chief, Roadside Safety Technology Unit
Office of Materials Engineering and Testing Services - MS #5
P.O. Box 19128
Sacramento, California 95819-0128

Dear Mr. Peter:

In your February 17 letter to Mr. Henry Rentz, you requested Federal Highway Administration's acceptance of the California Department of Transportation Type 70 Bridge Rail at the National Cooperative Highway Research Program (NCHRP) Report 350 test level 4 (TL-4). To support this request, you sent us a copy of your report: "Vehicle Crash Tests of the Type 70 Bridge Rail," dated January 1998, and a copy of a video tape documenting the certification tests that were conducted.

Our review of this material indicated that the Type 70 Bridge Rail is an 81O-mm tall concrete barrier with its traffic face sloped at a constant 9.1 degrees away from traffic. This face geometry is identical to your Type 60 roadside/median barrier that was accepted for use on the National Highway System (NHS) at TL-3 in my February 4 letter to you. However, the Type 70 Bridge Rail has a vertical back face with some architectural treatment and is more heavily reinforced than the Type 60. Design details are shown in Enclosure 1.

We noted that three tests were reported, including test 4-12 with an 8000 kg single-unit truck impacting the barrier at an angle of 15 degrees and a speed of 80 km/h Each of these tests met appropriate NCHRP Report 350 evaluation criteria. The individual test results are summarized in Enclosure 2. We noted also that test 4-11 was re-run after a first unsuccessful attempt in which the pickup truck rolled over after impact. You theorized that the non-standard floating rear hub of the test vehicle caused the drive shaft to pull out of the transmission housing on impact and that the shaft then dug into the test track and precipitated the rollover. This test was then re-run with a pickup truck with a standard wheel hub. Considering the successful retest and the earlier pickup truck tests with your Type 60 constant slope barrier as well as successful pickup tests with the New Jersey. F-proftle. and the Texas Department of Transportation constant slope barrier. we are willing to consider test 512 (NCHRP Report 350 test 4-11) as an anomaly.

Based on the above, we consider the California Type 70 Bridge Rail a NCHRP Report 350 TL-4 design that may be used on the NHS when proposed by a State or local transportation agency. Since you did not provide any details on your transition design, nor submit any crash-test results, our acceptance is limited at this time to the design of the bridge rail itself. By copy of this letter. we will advise OUf field offices of this finding. Please call Mr. Richard Powers of my staff at (202) 366-1320, if you have any questions.


Sincerely yours,

/* Signature of Dwight A. Home */

Dwight A. Home
Chief, Federal-Aid and Design Division

2 Enclosures

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