Investigation and Evaluation of a MASH TL-4 Precast Concrete Bridge Railing

Abstract

Recently, a precast concrete bridge railing with unique connection details for barrier-to-deck and barrier-to-barrier interfaces was developed at the Institute of Transportation (InTrans)-Iowa State University (ISU). Successful laboratory experiments led to the current study, in which the primary objectives were to determine if the bridge railing system complied with the American Association of State Highway and Transportation Officials (AASHTO) Manual for Assessing Safety Hardware (MASH) Test-Level 4 (TL-4) impact safety standards through a sequence of stages, including pre-crash simulations and one full-scale crash test with a 10000S single-unit truck (SUT). Initial analyses incorporated LS-DYNA computer simulations emulating MASH TL-4 impacts on two prototype barrier configurations: a single-slope shape and a near-vertical shape. These simulations facilitated the discernment of the bridge rail length, reinforcement details, crashworthiness for passenger vehicles, selection of the single-slope shape for crash testing, and determination of a critical impact point for the 10000S SUT crash test. Subsequent modifications to the single-slope barrier system with inclined bar connections were predicated on these computational findings. A full-scale crash test assessed the bridge railing and the loading to the inclined steel anchor bars under MASH test designation no. 4-12, focusing on its impact safety performance and potential damage to the barrier and bridge deck. In test no. ABCBRM-1, the single-unit truck, was successfully contained and redirected, with the barrier and deck sustaining negligible damage, and all safety performance criteria were within acceptable limits as defined in MASH. The study findings demonstrated that the modified single-slope, precast concrete bridge rail system met the MASH TL-4 impact safety criteria.