Speaker: Scott Rosenbaugh, M.S.C.E
When: Friday, October 10th, 10:50am-11:50am
Where: KH A510 (Lincoln), PKI 160 (Omaha)
Zoom: https://unl.zoom.us/j/94281831713
Title: W-Beam Bridge Rails and Culvert Treatments for Low-Volume, Rural Roads
Abstract: W-beam and Thrie-Beam guardrails are commonly used as bridge rails on low-volume and rural bridges. However, a recent survey of such bridges throughout the mid-west revealed numerous recurring safety issues associated with these bridge rails including 1) a lack of guardrail anchorage required to develop tension in the rail, 2) guardrail bluntends that become vehicle spearing hazards, 3) oversized support posts that pose as vehicle snag hazards, and 4) inadequate guardrail lengths that do not properly shield vehicles from the hazard below the bridge.
Recently, a few low-cost W-beam bridge rails that have been developed for use on low-volume, rural bridges that satisfy all of the current safety standards found in AASHTO’s Manual for Assessing Safety Hardware (MASH). These bridge rails utilize standard W-beam guardrail segments and smaller S3x5.7 support posts that provide adequate railing strength while also limiting impact loads transferred to the bridge deck. Various configurations of these bridge railings have been developed for either top-mounted or side-mounted post attachments, and these bridge railings can be configured to satisfy either Test Level 2 or Test Level 3 safety performance criteria. Thus, there are multiple options to address site specific needs. Over the past few decades, concrete box culverts have been used as small bridges over creeks and streams on low-volume and rural roadways. Fortunately, similar weak-post guardrail systems have been adapted for the treatment of concrete box culverts in the same manner as a bridge rail.
Therefore, these weak-post, W-beam guardrail systems provide a cost-efficient barrier system for bridges and culverts on low-volume and rural roads. The presentation will cover the development and crash testing of these guardrail systems. Further, installation and implementation guidance will be provided.