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Phase II Ponderosa Pine Round-Post Equivalency Study

REPORT NUMBER

TRP-03-315-14

AUTHORS

Scott Rosenbaugh, Ronald Faller, Brad Winkelbauer, Tyler Schmidt

PUBLICATION DATE

2015-02-04

ABSTRACT

The research objective was to determine the appropriate size and embedment depth of a round Ponderosa Pine (PP) post for use as a surrogate for the standard 6-in. x 8-in. x 72-in. (152-mm x 203-mm x 1,829-mm) Southern Yellow Pine (SYP) post used in G4(2W) guardrail systems. Nine dynamic component tests were conducted on the standard rectangular SYP posts and round PP posts in two separate rounds. Round 1 of testing was conducted in strong soil and evaluated the posts' ultimate strengths. Results indicated that a minimum diameter of 8⅝ in. (219 mm) should be used for PP posts to replicate the SYP post strength. Round 2 of testing was conducted within a moderately compacted soil and evaluated the soil resistance of each post. An embedment depth of 36 in. (914 mm) was found to provide equivalent soil resistance to the rectangular SYP post. Based on these test results, an 8⅝-in. (219-mm) diameter PP post with a 36-in. (914-mm) embedment depth was recommended as the surrogate post for the SYP post utilized in most U.S. standard G4(2W) guardrail systems.

KEYWORDS

Highway Safety, Roadside Safety, Guardrail, MGS, Dynamic Test, Bogie, Wood Post, Round Post, Southern Yellow Pine, Ponderosa Pine, and Equivalency

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