March 8, 2005
Refer to: HSA-10/CC88
Mr. Kaddo Kothmann
Road Systems, Incorporated
3616 Howard County Airport Road
Big Spring, Texas 79720
Dear Mr. Kothmann:On December 20, 2004, you requested Federal Highway Administration (FHWA) acceptance of modified versions of your original Sequential Kinking terminal (SKT), your reduced-length Sequential Kinking Terminal (SKT-LITE), and your Flared Energy Absorbing Terminal (FLEAT). The modifications were needed to match these terminals, which were originally tested as standard W-beam terminals, to the higher Midwest Guardrail System (MGS) which was formally accepted as an National Cooperative Highway Research Program (NCHRP) Report 350 test level 3 (TL-3) barrier on March 1, 2005 (acceptance letter B-133). To verify continued crashworthiness of the new designs, the Midwest Roadside Safety Facility (MwRSF) conducted the following four tests:
To match the MGS barrier design, similar modifications were made to the original SKT, SKT-LITE, and FLEAT designs. These were the following:
The NCHRP Report 350 requires up to seven crash tests to determine the adequacy of a traffic barrier terminal at TL-3. However, since the original designs for attachment to standard W-beam guardrail remain crashworthy, only those tests that are likely to be affected by the design changes noted above are considered necessary. You successfully completed test 3-31 (head-on into the SKT-MGS with the 2000-kg pickup truck) and test 3-35 (20-degree impact with the pickup truck at post 3 with a FLEAT terminal). Also with a FLEAT terminal, you conducted the small car head-on test and the Critical Impact Point (CIP) test. Summary sheets for each of these tests are shown in Enclosure 1 to this letter. English-unit drawings for steel-post versions of each of the tested applications are shown in Enclosure 2. I understand that corresponding drawings for wood-post designs are available from you upon request, as well as metric-unit drawings for each of the design configurations.
The modifications to the SKT and FLEAT terminals described above are acceptable and both terminals remain TL-3 designs that can be used on the National Highway System (NHS) when connected to the MGS barrier. While the barrier itself is non-proprietary, your terminals are proprietary and remain subject to the conditions stated in Title 23, Code of Federal Regulations, Section 635.411 when used on Federal-aid highway projects, except exempt, non-NHS projects.
/Original signed by/
John R. Baxter, P.E.
Director, Office of Safety Design
Office of Safety