Studying road restraint systems to develop new guidelines

Key to understanding the needs and tools of road infrastructure management for preventing run-off-road crashes or minimising their consequences, is to identify the hazards and sources of hazards caused by wrong or improper use of road safety devices and identify errors in the design, structure, construction and operation of road safety devices. Studying such an extended scope of the problem required fieldwork and surveys with road authorities, designers, road safety auditors and road maintenance services. An outline of new guidelines could only be developed after understanding the effects of restraint systems, the design, additional elements, type of road and safety barrier location on a road or engineering structure and the road and traffic conditions on their functionality and safety. The paper will present the preliminary results of this research (research project – ROSE). After an in-depth study of the literature, a comparative analysis was made of selected guidelines and principles of using road safety devices in nearly 40 countries from different continents. The parameters which were identified to influence the choice of safety barriers were divided into thematic groups. Two main categories were identified based on the theory of risk: probability and consequences. Probability included factors which, if present in the road cross-section, may make an accident more likely. Consequences included factors which increase the severity and consequences of an accident. One way to understand the functionality of road safety devices is to build numerical models and conduct simulation tests of virtual crash tests. While the literature on numerical road safety device studies includes plenty of detailed works, there are no cross-cutting papers to summarise the partial results of the work of many research teams and condense the theoretical formulations and numerical implementations for the purposes of crash test analysis. The paper will present a proposed approach to such work along with preliminary results of numerical studies for selected problems using road safety devices such as safety barriers on horizontal curves, the effect of kerbs on bridges or the location of obstacles within the barrier’s working width. The paper will discuss assumptions to a methodology of numerical models, calculations and automated processing of data to help with assessing the functionality of the devices. The paper will outline the design of the method for selecting optimal road safety devices. This will be based on device selection factors, fieldwork, surveys and simulations. The models and procedures used in the method will help to identify and link different sources of hazard when using road safety devices to tackle a specific event and will help to identify the weaknesses in the safe use of types of road safety devices. The method will take account of the effect of different factors on optimising device selection. They are: types of hazard sources, road class and its parameters, road traffic parameters (volume, structure, speed). The method will be further developed in new research