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Design of an Improved Post for Use in a Non-Proprietary High-Tension Cable Median Barrier

REPORT NUMBER

TRP-03-286-15

AUTHORS

Bob Bielenberg, Tyler Schmidt, Ronald Faller, Scott Rosenbaugh, Karla Lechtenberg, John Reid, Dean Sicking

PUBLICATION DATE

2015-05-07

ABSTRACT

The objective of this research study was to develop a revised post section for the non-proprietary high-tension cable median barrier that improved the safety and function of the post by lowering strong-axis forces. A total of twenty dynamic component tests were performed, along with one cable pull test - ten tests with the 7-gauge C-section post, eight with the 10-gauge C-Section posts, and three with the Midwest Weak Post (MWP). The tests were conducted with the posts installed in either a compacted, crushed limestone soil or a rigid sleeve in order to determine the force vs. deflection and energy vs. deflection characteristics of the various post configurations. Although the C-section posts were found to provide up to 58.7 percent and 70 percent reductions in strong-axis forces through 10 in. (254 mm) and 15 in. (381 mm) to that of the S3x5.7 (S76x8.5) posts, the C-section hinged at the location of the keyway when a keyway was punched in the posts and left a 15-in. (381-mm) stub sticking out of the ground. This behavior caused concerns for occupant compartment intrusions. Subsequently, the MWP was designed to bend over at the groundline while maintaining the desired strong- and weak-axis post forces. In dynamic tests, the MWP was found to provide up to 54.3 percent and 64 percent reductions in strong-axis forces through 10 in. (254 mm) and 15 in. (381 mm), as compared to the S3x5.7 (S76x8.5) posts. The weak-axis forces were found to be up to 14.3 percent and 6.7 percent greater than the S3x5.7 (S76x8.5) post through 10 in. (254 mm) and 15 in. (381 mm). These comparisons indicated that the MWP section had significantly reduced strong-axis capacity as compared to the S3x5.7 (S76x8.5) post while maintaining similar weak-axis capacity to the S3x5.7 (S76x8.5) post, as intended.

KEYWORDS

Highway Safety, Crash Test, Roadside Appurtenances, MASH, Cable Median Barrier, C-Section Posts, W3x5.7 Posts, Midwest Weak Post and Bogie Test

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