Comparison of Safety Performance of Italian and Canadian Urban Intersections

摘要

In Italy, almost half of all road accidents occur at intersections, mostly in urban areas. In order to reduce accident rates, in recent years several signalized intersections have been converted to roundabouts; this is due to the widespread belief that this kind of intersection has many advantages in terms of safety and operations. To assess if the construction of a roundabout is justified at a certain intersection compared to signalized form of control, it is necessary to develop the powerful statistical tool known in the literature as a Safety Performance Functions (SPFs). Recent Italian estimations of SPFs calibrated for this purpose will be presented and compared. These pertain to a database from the Municipality of Palermo City (Southern Italy) and from the Municipality of Novara City (Northern Italy). These SPFs are also compared with recently calibrated Canadian SPFs to illustrate differences in safety performance between Italian and Canadian intersections. The results are mixed. Overall, the Canadian models are more similar to those estimated for Novara City, which are based on very limited data, and for which the same negative binomial error distribution was used. This would suggest that these Italian models can be used to in procedures to assess the justification of conversion from 4-leg signalized intersections to roundabout, and can be considered generally for use in the safety estimation procedures.