Bridges

This study relates to ongoing Austroads Project ABT6152, which seeks to verify compliance of a bridge barrier design against relevant Australian Standards that have been recently updated, and the American Association of Highway and Transportation Officials (AASHTO) Manual for Assessing Safety Hardware (MASH), revised in 2016. There is a lack in harmonisation between the barrier testing requirements specified within MASH, Australian Standard AS3845 (specifies the design of road barriers) and AS5100 (specifies the design of bridge barriers). Due to the increase in mass and height of heavy vehicles in Australia, higher mass and heights are used for AS5100 than those that exist in MASH. For example, for medium barrier performance, the AS5100 impact speed for a 36-tonne truck is 90km/h; 10km/h higher than the MASH TL5 truck requirement of 80 km/h (this difference equates to approximately 25% increase in kinetic energy). To address these inconsistencies, there is a critical need for synergy between road practitioners and bridge practitioners when designing bridge barriers.

After completion of a project workshop, a literature review, industry consultation and analysis of heavy vehicle field crashes, significant challenges were identified when certifying that bridge barriers installed in Australia meet or exceed stringent crash test requirements. This project involves physical crash testing of the Transport for New South Wales (TfNSW) type MAO medium performance barrier design. Given crash testing costs are considerable, there is merit in completing theoretical validation before physical tests are carried out. To increase confidence that the bridge barrier design will perform as expected in the physical crash tests, Finite Element Analysis (FEA) testing has been performed on the bridge barrier design. This is the first step in certifying compliance of the bridge barrier design with AS5100. The results of the FEA indicate the barrier will comply with AS5100 when crash-tested. The paper and presentation will present results of this project to date and inform of the future steps to finalising.