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Development and Testing of a Bridge Rail for Low-Volume Roads

REPORT NUMBER

TRP-03-407-20

AUTHORS

Scott Rosenbaugh, Jacob DeLone, Ronald Faller, Bob Bielenberg

PUBLICATION DATE

2020-09-03

ABSTRACT

A new steel bridge rail was developed for use on low-volume bridges. The railing consisted 31-in. tall, 12-gauge W-beam guardrail mounted on S3x5.7 posts, which were supported by steel square-tube sockets attached to the side of the bridge deck. The sockets were to be attached to the steel C-channel that is typically placed along the edges of rural bridge decks in the state of Nebraska. The bridge railing was developed for use on both 7-in. thick cast in place decks and 12-in. thick pre-stressed concrete beam slabs. Various welded and bolted socket-to-channel attachment designs were evaluated through dynamic bogie testing on both deck types. Posts were impacted both laterally and longitudinally to evaluate the strength of the attachments and the potential for deck damage during vehicle impacts. Upon reviewing the bogie testing results, the project sponsor selected the bolted attachment using embedded coupling nuts and threaded rods as the desired attachment design for full-scale testing. Full-scale crash testing was conducted according to test designation no. 2-11 of the American Association of State Highway Transportation Officials (AASHTO) Manual for Assessing Safety Hardware (MASH 2016). The 2270P vehicle impacted the bridge rail at 25.5 degrees and 44.2 mph and was successfully contained and redirected. Damage to the bridge rail consisted of bent posts and deformed guardrail. No damage to the deck or sockets was observed. Thus, the tests passed all evaluation criteria of MASH 2016 test designation no. 2-11. The new railing was deemed MASH TL-2 crashworthy with a post spacing of 75 in. and MASH TL-3 crashworthy with a post spacing of 37.5 in. BARRIER VII simulations showed that the new railing could be directly connected to the Midwest Guardrail System (MGS) without a transition. Guidance was provided pertaining to the length of guardrail required adjacent to the bridge rail.