Impact Analysis of Road Intrinsic and Extrinsic Conditions on the Safety Level: A Case Study

Road accident causes cannot always be linked to infrastructure issues due to the interaction between the three safe system components (infrastructure, vehicle performance, and human behaviour). Although the analysis of accident records attributes the most commonly stated reason of accidents to road users, road infrastructure has a significant role: infrastructure defects and elements with poor safety performance may be the cause and more often a contributory cause of crash events. The main aim of this paper is to focus attention on the several existing road network safety deficiencies, due, for example, to the presence of noncomplying elements with the latest safety regulations or to inefficient maintenance policies. Road safety inspections (RSIs), established by Directive 2008/96/EC (in Italy implemented through the Decree n.35/2011), can be considered an efficient and preventive tool to identify infrastructure safety problems and increase the safety potential of the system. In this study, a systematic approach of RSIs procedures has the purpose of a safety performance evaluation of a high-risk rural road in Southern Italy. Correlating RSI outcomes with accident analysis in order to identify a potential relationship between deficits concerning road infrastructure and the localisation and severity of crashes, important results are found relating to the strong correlation between road markings issues and the number of accidents. Also the impact of private access points on accident rate is investigated, finding that an increasing density of access points leads to a higher frequency of accidents.