Standard barrier designs for roadsides, medians, and bridges specified by the new York state department of public works were revised after 6 years of research. Comprehensive theoretical analysis of forces generated between vehicle and barrier during impact produced four mathematical models collision with a given barrier. Models were programmed for computer solution. Three provided the force deflection curve of the barrier in the case of a pure tension rail /cable/, a combination of tension and bending /w-beam/, and pure bending /box beam/. the fourth model gave the trajectory of the vehicle using the appropriate force-deflection curve as input. Forty-eight full-scale collisions between standard- size passenger cars and various barriers were carried out. Speeds of up to 60 mph and impact angles of up to 45 deg were selected as the most severe conditions expected on a highway. Dynamic tests were conducted on various guardrail posts embedded in different soils. Contribution of the post to barrier system strength and optimum post size and embedment conditions were determined. Results of tests relating directly to barriers finally adopted were presented. Improved barriers were described, and data were given on appropriate barrier selection.
Samenvatting