In this project, the NC Two-bar Metal Rail (2BMR) was evaluated for compliance with the 2016 edition of Manual for Assessing Safety Hardware (MASH) under Test Level 3 (TL-3) conditions. Two full-scale crash tests, MASH Tests 3-10 and 3-11, were performed on a 90-ft section of the 2BMR and successfully passed all MASH evaluation criteria. A finite element (FE) model of the test section was created and used in simulations to determine the critical impact points and to predict the 2BMR performance under MASH TL-3 conditions. The simulation results were shown to agree well with test data and all the performance metrics met the MASH requirements. An application was submitted to FHWA to obtain a letter of eligibility for federal-aid reimbursement and the application was approved in August 2021.
Vehicle trajectories of 2007 Chevy Silverado impacting the 2BMR. (a) With expansion splice as reference; and (b) with the post as reference
In addition to the work on 2BMR, the FE models of three additional bridge rails were created: the Oregon Rail, the Three-bar Metal Rail, and the Classic Rail. Finite element simulations were performed to evaluate their performance under different MASH test conditions: the Oregon Rail under MASH TL-4 conditions, the Three-bar Metal Rail under MASH TL-2 and TL-3 conditions, and the Classic Rail under MASH TL-2 and TL-3 conditions. The simulation results demonstrated the performance trends of these three bridge rails as well as indicated some potential issues or safety concerns.
Finite element modeling and simulation were shown to be a powerful tool for assisting roadside safety research. The FE models of the vehicles and bridge rails from this project are readily available for use in other investigations.
