Examining Median Types Near Unsignalized Intersections to Identify Interplay Between Safety and Access Management

This study is concerned with access management analysis related to unsignalized intersections and access points. All possible median types that could exist across from unsignalized intersections were identified, which included closed, directional (allowing access from both major road directions), open, undivided, two-way left turn lane, and mixed (allowing access from a single major road direction only). The study made use of data collected from 2500 unsignalized intersections in the State of Florida. The analysis included differentiating between crashes that are related to medians and intersection-related to convey a better understanding of safety deficiencies to facilitate the countermeasures recommendation. Identifying different median-related crash patterns at each median was also investigated. The binary logit approach was implemented in this study as a new promising application for understanding those factors affecting median-related crashes at different median types. The bivariate probit model was also used to examine the interrelation between median type and median-related crash patterns. Both approaches succeeded in identifying those factors affecting median-related crash occurrence. Some of the significant factors were median width, speed limit on major roads, the annual average daily traffic volume on the major road, the spatial covariates represented by the upstream and downstream distances to the nearest signalized intersection, and crash pattern. The study also recommended safety countermeasures for improving access management across from unsignalized intersections.