Report Result

TRP-03-478c-25

Scott Rosenbaugh, Mojdeh Pajouh, Ronald Faller

2025-07-30

The Hawaii Department of Transportation (HDOT) has utilized bridge railings similar to the Hawaii Modified Natchez Trace Bridge Rail and its associated approach guardrail transition (AGT) to safely redirect vehicles on or near bridges. However, the crashworthiness of the bridge railing and AGT had not been evaluated under current impact safety standards, the Manual for Assessing Safety Hardware (MASH). As part of a previous phase of this project, crash testing of the Hawaii Modified Natchez Trace Bridge Rail resulted in excessive occupant compartment deformations that failed to satisfy the safety performance criteria of MASH Test Level 3 (TL-3). Subsequently, the railing was redesigned with a vertical face and renamed the Hawaii Concrete Post and Beam Bridge Railing. This new railing was crash tested in accordance with MASH test designation nos. 3-10 and 3-11 and passed MASH TL-3 safety criteria. Documented herein, HDOT’s AGT to open concrete bridge rail was redesigned to ensure crashworthiness to MASH TL-3. The geometry of the bridge rail end post was modified such that its cross section gradually transitioned from a solid, vertical-faced parapet to a cross section matching that of the Hawaii Concrete Post and Beam Bridge Rail. Additionally, the length of the bridge rail end post was shortened to optimize installation costs. Finally, the post and rail components of the AGT were modified to match the configuration of another AGT to concrete parapet that had already passed MASH TL-3 crash testing. Since all of the components of this AGT configuration had already been shown to be MASH TL-3 crashworthy, this new AGT to the Hawaii Concrete Post and Beam Bridge Rail was also determined to be MASH TL-3 compliant.

Highway Safety, Roadside Appurtenances, Approach Guardrail Transition, MASH, Test Level 3, Thrie Beam, Concrete Post, Beam Bridge Rail

TRP-03-478c-25.pdf