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Development of a 7.62-m Long Span Guardrail System




Karla Lechtenberg, Bob Bielenberg, Dean Sicking, Ronald Faller, John Rohde




A 7.62-m long span guardrail system was developed for use over low-fill culverts. The long span design was constructed with two 2.66-mm (12-gauge) thick nested W-beam rails totaling 30.48 m in length. The nested W-beam rail was supported by sixteen W150x13.5 steel posts and six standard CRT posts, each measuring 1,830-mm long. Post spacings were 1,905-mm on center except for the 7.62-m spacing between the two CRT posts surrounding the unsupported span. The research study included computer simulation modeling with BARRIER VII and full-scale vehicle crash testing, using -ton pickup trucks. The first test, impacting at a speed of 101.3 km/hr and an angle of 25.4 degrees, was unsuccessful because the barrier system failed at the simulated BCT anchorage end. Consequently, the long-span barrier system was modified to include additional guardrail posts and new BCT anchorage hardware. The second test, impacting at a speed of 102.7 km/hr and an angle of 24.5 degrees, was unsuccessful due to vehicle rollover. The safety performance of the long-span barrier system was determined to be unacceptable according to the Test Level 3 (TL-3) evaluation criteria specified in NCHRP Report No. 350, Recommended Procedures for the Safety Performance Evaluation of Highway Features.


Highway Safety, Guardrail, Roadside Appurtenances, Longitudinal Barrier, Box Culvert, Crash Test, Compliance Test

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