Federal Highway Administration
400 Seventh St., S.W.
Washington, D.C. 20590
March 10, 2006
In Reply Refer To:HSA-10/B-144
Mr. Alex F. Talbott
LifeNet SoftWalls, LLC
8311 Shelbyville Road
Louisville, KY 40222
Dear Mr. Talbott:
In your February 2 letter, you requested the Federal Highway Administration (FHWA) acceptance of a barrier system comprised of used automobile tires called the LifeNet SoftWalls Median Barrier System.
You also sent me copies of test reports prepared by the Transportation Research Center in East Liberty, Ohio, that documented the results of the National Cooperative Highway Research Program (NCHRP) Report 350 tests 3-10 and 3-11. Initial staff review of these reports revealed some errors and inconsistencies that needed to be addressed. Corrected copies of these reports were received electronically on March 3.
The tested LifeNet Softwalls barrier system consisted of approximately 400 used automobile tires with diameters ranging from 23 inches to 31 inches. These tires were arranged in stacks seven tires high and connected together with tire treads from other tires. Enclosure 1 shows the component parts and the layout of the test installation. As can be seen, the installation was set in a 4.5 foot offset zigzag pattern with each individual segment consisting of 6 interlocking stacks of tires. The barrier height was 4.5 feet and its overall length was 105 feet. The test installation was freestanding on a flat concrete surface and was unanchored. Tennis balls were used under the tread strap sets to simulate drainage risers.
In test 3-10, the small car impacted the barrier at 100.7 kmh and an impact angle of 20 degrees approximately 80 feet downstream from the beginning of the installation. The vehicle was effectively "captured" (rather than redirected) by the barrier, which straightened out during the impact and slid along the ground approximately 17 feet longitudinally and 12 feet laterally. Occupant impact velocity was 11.6 m/s and the ridedown acceleration was 9.3 G's. In test 3-11, the pickup truck impacted at 100.3 kmh and at an impact angle of 25 degrees, also approximately 80 feet from the upstream end of the test installation. Again, the vehicle was captured upright by the barrier as it was straightened out from its original zigzag alignment. The barrier moved approximately 40 feet longitudinally and 16 feet laterally. Occupant impact velocity was 9.7 m/s and the ridedown acceleration was 5.7 G's. In both tests, the selected impact point was 80 feet from the upstream end of the test installation thus establishing the design length of need point. Enclosure 2 shows the summary sheets for the two tests that were run.
Based on the reported results of these tests, the LifeNet SoftWalls Median Barrier System meets the evaluation criteria in the NCHRP Report 350 for a test level 3 longitudinal barrier and may be used on the National Highway System if selected for use by a transportation authority. In both tests, acceptable crash performance was contingent upon the test vehicles being stable immediately prior to impact (i.e., the vehicles' suspensions were neither compressed nor extended) and upon the LifeNet Softwalls installation being free to translate both longitudinally and laterally along the ground. End users may require additional testing if your barrier is installed on sloping terrain or on a surface that may prevent or restrict its free movement when struck by a vehicle.
Please note the following standard provisions that apply to this acceptance letter:
/original signed by/
John R. Baxter, P.E.
Director, Office of Safety Design
Office of Safety
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