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Development of a 7.62-m Long Span Guardrail System

出版	Midwest States Regional Pooled Fund Program, 1999
URL	http://books.google.com.hk/books?id=CT5HPQAACAAJ&hl=&source=gbs_api

註釋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 1,999-kg 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 Breakaway Cable Terminal (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 the Test Level 3 (TL-3) evaluation criteria specified in NCHRP Report No. 350, "Recommended Procedures for the Safety Performance Evaluation of Highway Features" (1993)