Crash Testing and Evaluation of the TxDOT Type T8 Bridge Rail (407049-1)

The Texas Type T6 was previously crash tested and evaluated under NCHRP Report 230 guidelines. The two tests included a test with a 4500 lb passenger vehicle traveling at 61.5 mph and 27.5 degrees, and a test with a 2282 lb passenger vehicle traveling at 58.0 mph and 14 degrees. The T6 bridge rail performed acceptably during these two tests. However, with the adoption of NCHRP Report 350, TxDOT required reevaluation of the bridge rail using the 4409 lb pickup truck. Several crash tests have been performed on variations of the T6 bridge rail. No crash test to date has been successful with respect to NCHRP Report 350 TL-3 requirements. Reevaluation and redesign of the T6 post and base plate design has resulted from the previous testing. The performance of the T6 bridge rail and the vehicle stability issues associated with this design, has led to the development of the tubular T8 bridge rail that was tested for this project. With the height increased from 27 inches to 31 inches and the stiffness of the rail element increased for the tubular thrie-beam rail element, the crash performance of the T8 was expected to be improved over the T6 bridge rail design. In addition, the similarities between the T6 and T8 bridge rails would result in a more simple and cost effective replacement for the T6 bridge railings that are currently in place on scores of off-system bridges across the state. There was concern of performance of the Texas Type T8 bridge rail, as well as concern for vehicle stability. The pickup truck test is considered to be the critical test in the evaluation of the longitudinal barriers in terms of structural adequacy, vehicle stability, barrier override, and occupant compartment deformation. Reported herein are the details of the Texas Type T8 bridge rail, and the description of the pickup truck test and the results of that test. The TxDOT Type T8 bridge rail did not perform acceptably for NCHRP Report 350 test 3-11 due to vehicle rollover.