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Midwest Guardrail System (MGS) With Southern Yellow Pine Posts




David Gutierrez, Karla Lechtenberg (Polivka), Bob Bielenberg, Ronald Faller, John Reid, Dean Sicking




The Midwest Guardrail System (MGS) has previously been approved for use with various alternative species of wood posts. However, Southern Yellow Pine (SYP) is the most common wood guardrail post material in the United States. The goal of this research was to evaluate the MGS with rectangular SYP posts. In a previous test, the 6-in. x 8-in. x 72-in. long (152-mm x 203-mm x 1,829-mm) rectangular White Pine post was found to have 39 percent lower capacity than the 6- in. x 8-in. x 72-in. long (152-mm x 203-mm x 1,829-mm) Southern Yellow Pine post. This result indicated that the MGS with SYP posts would likely be successful, but full-scale crash testing was deemed useful to verify satisfactory safety performance and obtain dynamic deflection and working width data under Manual for Assessing Safety Hardware (MASH) TL-3 test conditions. The MGS was crash tested with 6-in. x 8-in. x 72-in. long (152-mm x 203-mm x 1,829-mm) Southern Yellow Pine posts. This system also used a 6-in. x 12-in. x 14¼-in. long (152-mm x 305-mm x 362-mm) blockout as well as 12-gauge (2.66-mm) guardrail sections. The design was evaluated using a small car (test no. 3-10) and a pickup truck (test no. 3-11) according to the testing standards established in the MASH. The MGS with Southern Yellow Pine posts met the MASH safety requirements for both full-scale crash tests. Following the full-scale crash testing, recommendations were given regarding the use of SYP posts in special MGS applications.


Highway Safety, Crash Test, Roadside Appurtenances, Compliance Test, MASH, MGS, Guardrail, Wood Post, and Non-Proprietary

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