Surface-Mounted Post Retrofit for Approach Guardrail Transitions: Phase I
REPORT NUMBER
TRP-03-492-25
AUTHORS
Scott Rosenbaugh, Gnyarienn Kumar, Cody Stolle, Ronald Faller
PUBLICATION DATE
2025-12-16
ABSTRACT
The objective of this project was to develop retrofit options for approach guardrail transitions (AGTs) where obstructions prevent the proper installation of the guardrail posts. The project began with a survey of state departments of transportation to better understand the ground obstructions and site issues that were preventing posts from being properly installed. From this survey, it was determined that the best retrofit option would be a surface-mounted post. Thus, the project scope became the development and testing of a surface-mounted W6x15 AGT post. The surface-mounted post was required to provide similar strength to a standard W6x15 AGT post embedded in strong soil. The post was also required to prevent damage to the anchors and supporting concrete slab to avoid costly repairs when impacted. Additionally, the anchors were limited to an embedment of 6 in. to fit within an 8-in. thick concrete slab. Multiple post assemblies were configured with varying base plate sizes, base plate thicknesses, anchor rod diameters, post-to-plate weld specifications, weakening holes and cuts in the compression flange of the post. The configurations were evaluated through dynamic component testing. In all, nine component tests were conducted over three rounds of testing. Ultimately, Post Assembly M consisting of a W6x15 post with Ø1¼-in. x 3-in. slots in the compression flange and a 1-in. thick base plate was selected as the preferred surface-mounted post configuration. This configuration was recommended for further evaluation via Manual for Assessing Safety Hardware (MASH) crash testing, which would occur in a future Phase of this study.
KEYWORDS
Highway Safety, Approach Guardrail Transition, Retrofit, Post, Surface-Mounted, LS-DYNA, Dynamic Component Testing, Bogie Testing