Development of a TL-3 Deep Beam Tubular Backup Bridge Rail (476890-1)

The objective of this study is to investigate the performance of the Ohio Department of Transportation (ODOT) Deep Beam bridge rail system per the National Cooperative Highway Research Program (NCHRP) Report 350 TL-3. Analytical study, computer simulation, and testing approach are to be addressed to accomplish the objective of this study. The final expected product is a design of the ODOT Deep Beam bridge rail system with any needed retrofit that will bring the system in compliance with the NCHRP Report 350 performance criteria per TL-3. The modified ODOT Deep Beam bridge rail design is shown to be successfully able to pass NCHRP Report 350 Test Level 3 assessment criteria. This conclusion is based on engineering strength analysis and nonlinear finite element simulation. The added rail on the top of the bridge rail helped reduced potential vehicular dynamics instability that may occur if only the original rail (less height) was used. Also, the additional lower rail (rub rail) provided protection against tire snagging in the opening below the main rail and the deck. This snagging mode could be detrimental for small vehicle impacts due to the subsequent excessive deformation and increased ridedown acceleration. This system can be implemented in the field subsequent to Federal Highway Administration (FHWA) Office of Safety approval of the simulation results presented herein or the full scale crash tests that were recommended. The modified design presented herein represents a retrofit that can be installed by a qualified construction crew. The research team recommends using the ODOT transition GR-3.4. A modification is suggested for that transition detail to accommodate the added top and rub rail in the modified ODOT Deep Beam bridge rail. One example would be to turn the top rail toward the middle rail at an angle and to extend the rub rail along a few transition posts and then turn it back toward the field side.