VEHICLE IMPACT TESTING OF LIGHTWEIGHT LIGHTING STANDARDS. FINAL REPORT

The results of seven full-scale vehicular crash tests on 35-ft-high breakaway lighting standards with 20-ft-long mast arms are presented and compared with the recommended crash test criteria in NCHRP Report 230 and with the new 1985 AASHTO Standard Specifications for structural supports. The test devices consisted of 1) an aluminum lighting standard with cast aluminum breakaway couplings, 2) a lightweight steel lighting standard with cast aluminum breakaway couplings and with a triangular slip base, and 3) a typical California Department of Transportation (Caltrans) type 31 lighting standard with triangular slip base. Honda Civic automobiles (1979 vintage) each weighing 1800 lb were used as the crash vehicles. Tests were performed at 20 and 60 mph with centered and off-centered impacts. All the lighting standards tested met the requirements of NCHRP Report 230 with minor exceptions. The 1985 AASHTO Standard Specifications for breakaway bases, however, were met in all seven crash tests. Although the die-cast aluminum coupling proved to be an effective breakaway device when impacted by 1800-lb cars, excessive porosity and lack of compliance with Caltrans specifications preclude the use of these couplings as a standard Caltrans breakaway device. The Caltrans triangular steel slip base proved to be an effective breakaway device when impacted by 1800-lb cars.