Report Result

Back to Search

Crash Testing of Missouri's W-Beam to Thrie-Beam Transition Element




Karla Lechtenberg, Ronald Faller, Dean Sicking, John Reid, John Rohde, Jim Holloway




For longitudinal barriers, it is common practice to use standard W-beam guardrail along the required highway segments and to use a stiffened thrie beam guardrail in a transition region near the end of a bridge. As a result of the differences in rail geometries, a W-beam to thrie beam transition element is typically used to connect the two rail sections as well as to provide continuity in the barrier system. However, the W-beam to thrie beam transition element has not been evaluated according to current impact safety standards. Therefore, an approach guardrail transition system, including a W-beam to thrie beam transition element, was constructed and crash tested. The transition system was attached to Missouri's thrie beam and channel bridge railing system. The research study included full-scale vehicle crash testing, using a small car and a 3/4-ton pickup truck. The first test, with a small car impacting at a speed of 99.5 km/hr and an angle of 25.7 degrees, was successful as the vehicle was safely redirected. The second test, with a 3/4-ton pickup truck impacting at a speed of 98.3 km/hr and an angle of 25.3 degrees, was unsuccessful as the vehicle pocketed in the rail and then rolled onto its side. The tests were conducted and reported in accordance with the requirements specified in NCHRP Report No. 350, Recommended Procedures for the Safety Performance Evaluation of Highway Features. The safety performance of the W-beam to thrie beam transition element was determined to be unacceptable according to Test Level 3 (TL-3) of the NCHRP Report No. 350 criteria.


Highway Safety, Guardrail, Roadside Appurtenances, Longitudinal Barrier, Crash Test, Compliance Test, W-Thrie Transition

Other files to download