December 9, 2003

Refer to: HSA-10/CC75B

Owen S. Denman, P.E.
President
Barrier Systems, Incorporated
180 River Road
Rio Vista, California  94571-1208

Dear Mr. Denman:

In your November 3 letter, you requested formal Federal Highway Administration acceptance of a “family” of crash cushion designs called the Universal TAU-II Crash Cushion System.  The primary difference from the original parallel-sided TAU-II designs was the introduction of variable-width diaphragms that result in a 5-degree outward flare of the attenuator side panels to allow direct shielding of hazards up to 2.6 m (8.5 feet) in width.  Included with your letter were copies of Safe Technologies, Incorporated, October 2003 report, “NCHRP Report 350 Crash Test Report – Barrier Systems, Incorporated.  Wide TAU-II Crash Cushion System” and CD-ROMs and VHS tapes of the certification tests that were run.  In preliminary discussions with members of my staff, it was mutually agreed that selected tests on both the narrowest and widest versions of the wide TAU-II would be sufficient to accept less critical configurations of these two designs as also meeting NCHRP Report 350 evaluation criteria.  The two configurations tested and the summary test results are shown in Enclosures 1 through 7.

Based on these test results, I agree that the TAU-II configurations shown in Enclosure 8 may be considered acceptable for use on the National Highway System with the following caveats:

• The four designs tested to Report 350 (including earlier TL-2 and TL-3 tests of the parallel-sided designs), and all those in between, may be considered to meet all pertinent evaluation criteria for the speeds listed.  This includes the systems in Enclosure 8 for impact speeds of 70, 80, 90 and 100 km/h that have 3, 4, 5, 6, 7 or 8 bays, respectively.
• The tested 10-bay parallel-sided configuration met Report 350 evaluation criteria for the head-on impact with the 2000P truck at a nominal speed of 110 km/h (70 mph).  The remaining designs shown under the 110 km/h heading may also be assumed to have adequate capacity to stop the pickup truck impacting head-on at 110 km/h within the occupant risk limits recommended in NCHRP Report 350 and to satisfy all test requirements at the standard TL-3 impact speed of 100 km/h.
• Based on favorable comparisons of predicted OIV's and ridedown accelerations with actual values from your previous 70-km/h test of the parallel-sided TL-2 design, I will also accept the 50 km/h and 60 km/h system designs shown in Enclosure 8 based upon predicted OIV and G values being lower than Report 350 preferred values.

Sincerely yours,

                                                                        /Original signed by/

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

8 Enclosures

FHWA:HSA-10:RPowers:tb:x61320:12/3/03

cc:        HSA-10 (Reader, HSA-1; Chron File, HSA-10; R. Powers, HSA-10)