Safety valuation methods at urban atypical\ud intersections. Analysis of infrastructural\ud scenarios

摘要

The definition of decision support tools for identifying ex ante evaluation issues for road safety measures is\uda new challenge for policymakers and designers managing road networks with the intention of improving\udtraffic safety for roads of their competence. This is consistent with explicit strategies on sustainability in the\udtransport sector established at European level, considering road safety as an essential prerequisite to warrant a\udsustainable mobility. Based on these considerations, the need for evaluation instruments of safety conditions both\udfor existing infrastructural schemes and for new road installations is recently arisen so that the identification of\udrisks involved in a particular road infrastructure is easier, as well as the definition of the priorities of intervention\udby means of technical measures. This is true in particular for road junctions characterized by a configuration not\udconforming to those ones recognized as safer. On this regard, the results of safety evaluations at roundabouts\udare not an exhaustive reference for geometric design where organizational schemes for circular intersections are\udsimilar to roundabouts but resulting from compromise choices as regards one or more geometric features of the\udroundabout. For this kind of atypical intersections specific safety problems are found, particularly in urban areas,\uddue to existing constraints of different kind and the great variety of geometric layouts they take on. Moreover,\udin these cases the possibility of applying the safety methods proposed in the literature regarding traditional\udroundabouts, as well as the road safety audit procedures, is also compromised. Based on these considerations, in\udthis paper ten case studies of this kind of intersections have been examined in order to verify the effectiveness\udof the risk analysis proposed by means of an infrastructural scenarios method. From the methodological point\udof view, the application of the accident delocalization procedure has allowed to highlight in relative terms the\udriskiness of different infrastructural scenarios arranging the organizational schemes of intersections. Moreover,\udthe proposed method can represent a useful tool for safety diagnostic analysis being able to provide informations\udfor policymakers and designers in order to address the infrastructural scenarios and the road schemes that need\udto be tested.