GUARDRAIL AND GUARDRAIL TERMINALS INSTALLED OVER CURBS

A barrier system was developed for installation where W-beam is placed over curbs. The guardrail design was constructed with a 2.66-mm (12-gauge) thick W-beam rail totaling 53.34 m in length. The W-beam rail was supported by twenty-five W150 x 13.5 steel posts, each measuring 1,830 mm long, and four standard BCT posts, each measuring 1,080 mm long. Post spacings were 1,905 mm on center. The concrete curb was a type "G" curb that measured 203 mm wide x 102 mm high x 19.05 m long. The research study included full-scale vehicle crash testing and live-driver curb testing, using a 2000-kg pickup truck. The full-scale test, impacting at a speed of 103.2 km/hr and an angle of 24.5 deg, was unsuccessful because the barrier system failed at the splice at post no. 12. The three live-driver curb tests, impacting at a speed of either 64 km/hr or 100 km/hr and an angle of 25 deg, helped to determine the curb, tire, and suspension interaction to use in future simulation work. 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."