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Full-Scale 1,800 lb. Vehicle Crash Tests on a 4-Bolt Breakaway Slipbase Design




Brian Pfeifer, Jim Holloway, Ronald Faller, Edward Post




The breakaway luminaire support concept has existed for many years and has proven to be a very effective safety device. The 4-bolt breakaway slipbase design was orginally developed in the State of Utah and has been very successful in 20 years of field implementation. The State Transportation Departments of Utah, Montana, Idaho, Wyoming, and Nevada requested that the 4-bolt breakaway system be evaluated for possible use on Federal-aid highway projects. Two full-scale 1,800 lb vehicle crash tests were conducted. Both tests had a centerline impact location; Test USBLM-1 was conducted at 15.0 mph and Test USBLM-2 was conducted at 57.5 mph. The full-scale vehicle crash tests were evaluated according to the performance criteria in NCHRP Report 230 and the 1985 AASHTO Specifications for Structural Supports. "Design Standards for Highways: Standard Specifications for Highway Signs, Luminaires and Traffic Signals," Federal Register, 23 CFR 625, which is an update to the 1985 AASHTO Specifications, was also used in the evaluation. The tests easily met all of the criteria set forth by the publications mentioned above. As a result of this, the safety performance of the 4-bolt breakaway slipbase design was determined to be satisfactory.


Highway Safety, Roadside Safety, Roadside Appurtenances, Breakaway Slipbase, Luminaire Support, Crash Test, Compliance Test, NCHRP 230

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