December 20, 2002

HSA-10/CC75A

Owen S. Denman, PE
President
Barrier Systems, Inc.
180 River Road
Rio Vista, CA 94571-1208

Dear Mr. Denman:

On October 4 you hand-carried two separate letters to Mr. Richard Powers of my staff.  The first was addressed to Mr. Frederick G. Wright, former Director of the Office of Highway Safety Infrastructure, and requested acknowledgement of a high-speed crash test and our concurrence in the acceptability of the various TAU-II system configurations shown in your Design Manual.  The second letter, addressed to Mr. Powers, provided information on TAU-II tests conducted on units anchored on an asphaltic concrete (AC) pad.   The original certification test series for the TAU-II used a reinforced concrete pad.

Included with the first letter were copies of Safe Technologies, Inc. May 2002 report, “NCHRP Report 350 Crash Test Results – TAU-II Crash Cushion (70 mph Test)” and CD-ROMs and VHS tapes of the test that was run.  That test was a modified NCHRP Report 350 test 3-31 with a 1991-kg pickup truck impacting a ten-bay (3 type A energy absorbing cartridges and 7 type B units) TAU-II head-on at 109.4 km/h.  The total attenuator length was 8978 mm.  All Report 350 evaluation criteria were met. The occupant impact velocity was reported to be 8.6 m/sec and the subsequent 10-millesecond ridedown acceleration was reported as 16.5 g's.  Based on this and previous tests, I agree that the tested unit met Report 350 evaluation criteria for a test level 3 crash cushion for test 3-31 at a nominal speed of 70 mph and that the system configurations shown in Enclosure 1 may be considered crashworthy and used on the National Highway System with the following caveats:

• The systems fully tested to Report 350, and all those in between, may be considered to meet all pertinent evaluation criteria for the speeds listed.  This includes the systems having 4, 5, 6, 7 or 8 bays and impact speeds of 70, 80, 85, 90 and 100 km/h, respectively.
  
  
• The tested 10-bay configuration meets Report 350 evaluation criteria for the head-on impact with the 2000P truck at a nominal speed of 110 km/h (70 mph)
  
  
• The 11- and 12-bay systems (and the 2- and 3-bay designs) may be assumed to have adequate energy-absorbing capacity to stop the pickup truck impacting head-on at the speeds shown for those configurations within the occupant risk limits recommended in NCHRP Report 350. 

The second letter referenced Safe Technologies, Inc. April 2002 report entitled “TAU-II Crash Cushion (Asphaltic Concrete Foundation)” and included videotapes of the crash tests.  For installation on an asphalt pad, the standard front cable anchor was modified (extended rearward) and required additional anchor bolts, as was the rear stand-alone compact backstop.  Based on the results of the tests you conducted, any of the anchoring designs shown on your foundation specifications sheet (Enclosure 2) may be considered acceptable for use with the TAU-II.

2 Enclosures