Selection of Roadside Safety Barriers Containment Level According to European Union Standards

The new European Standards EN 1317-1/2 define the performance classes of road restraint systems and induce a growing interest for roadside safety. However, analytical procedures, like benefit-cost analysis, are not used in Europe for the selection of specific roadside safety features at specific locations or for the development of warrants, policies, and guidelines on a systemwide basis. A model for the selection of roadside safety barrier performance level according to European Union standards is presented. The new procedure is an encroachment-based benefit-cost analysis that takes into account the effective performance level of road safety barriers on the basis of a comparison between the real-world impact conditions and the impact conditions of the full-scale crash tests performed according to the European Committee for Standardization standards. The behavior of the safety barriers in relation to the impact conditions has been studied by performing nonlinear dynamic finite element analysis of collisions of heavy-goods vehicles against steel road safety barriers. As a result of the study, analytical relationships between a barrier's containment capacity and impact conditions have been obtained. The expressions obtained allow one to evaluate the number of vehicles successfully redirected from the safety barriers in relation to the type of road, to the geometrical features of the road, to the traffic volume and composition, and to the safety barrier containment level. The model allows one to calculate the benefits arising from the greater number of vehicles redirected from safety barriers with greater level of performance and to compare roadside alternatives.