Influence on the Type of Intersection on Road Traffic Safety in Poland

Abstract

Analysing accidents in Polish towns it can be seen that a great majority of them occur at intersections. Moreover, it can be observed that some types of intersections are particularly dangerous. Hence, a question arises: which types of intersection can be considered to be more dangerous and which ones less dangerous? It needs to be emphasized that engineering projects do not include guidelines of this type. For designers of road infrastructure this kind of knowledge is very important. Therefore, the article aims at determining the degree of risk to a road traffic user, depending on the intersection type. The risk degree was defined as an average number of accidents falling on 1 vehicle and one traffic lane at the intersection inlet. Data on accidents which occurred in selected Polish towns during 3 years was used. In order to provide diversification of the intersections, each group included intersections with lower and higher significance for the city transport network so the traffic intensity was different for different intersections. The mean risk index as well as the dependence between the number of accidents and a variable characterizing the likelihood of collision were determined for each intersection type by means of regression analysis. Multi-lane roundabouts and intersections with a central island and extended inlets without traffic light signalling (both with right of way for one direction and the necessity of yielding way at each inlet) were found to be the most dangerous types of intersections. Intersections with priority to the right were found to be relatively dangerous, particularly those with traffic canalizing islands. Not channelized intersections with multi-phase traffic signalling were found to be potentially the safest ones. The research shows that single traffic lane roundabouts are potentially safe intersections, for which the risk degree is 2.5 times smaller than at multi-lane roundabouts.