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Dynamic Testing of Wooden Guardrail Posts-White and Red Pine Species Equivalency Study

REPORT NUMBER

TRP-03-154-04

AUTHORS

John Rohde, Jason Hascall, Karla Lechtenberg, Ronald Faller, Dean Sicking

PUBLICATION DATE

2004-09-21

ABSTRACT

Dynamic impact testing of 152-mm (6-in.) x 203-mm (8-in.) Red, White, and Southern Yellow Pine posts was performed. Dynamic tensile strength of the posts was primarily dependent upon the species of the post, with variation within each species attributable to the inconsistency of wood as a material and defects such as knots in the posts. The Southern Yellow Pine species tended to have the highest modulus of rupture with an average value of 37.23 MPa (5.40 ksi). White Pine yielded the lowest modulus of rupture, averaging 20.33 MPa (2.95 ksi). The modulus of rupture for Red Pine was 27.44 MPa (3.98 ksi). Based on these results, it is recommended that the use of Red and White Pine posts as guardrail line posts should require a new cross-sectional depth that would provide equivalent performance to Southern Yellow Pine. The width should remain the same. These changes will provide equivalent performance from Red and White Pine guardrail posts, without changing the soil reaction properties. The suggested depth is 238 mm (9 3/8 in.) for Red Pine species and 264 mm (10 3/8 in.) for White Pine species.

KEYWORDS

Highway Safety, Wooden Posts, Red Pine, White Pine, Southern Yellow Pine, Roadside Appurtenances, Bogie Crash Testing

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