Assessing Corridor Safety Performance at Approaches to Freeway Interchanges Using Lane Change Data

Abstract

Urban arterials near freeway interchanges are vital components of urban road infrastructure, connecting high-mobility freeway networks to the more accessible but lower-mobility urban network. In this study, the operational safety of these arterials is examined and the relationship between roadway geometry and safety performance is investigated. To assess operational safety, lane changes were considered as a risk factor, and the number of lane changes in each study subsegment was recorded. Segments were categorized as upstream or downstream based on their location relative to the intersection. The number of lane changes served as a safety performance measure, and was analyzed using linear regression models. The results indicate that downstream segments experienced decreased safety performance when median storages were present, while adding right running bays improved safety. Median openings and increased numbers of driveways negatively affected safety in these segments. For upstream segments, right turning bays were found to impair safety performance the most, followed by the number of driveways. The closer the driveways were to the interchange; the worse was the effect on the safety performance. In summary, this research highlights the importance of geometric design elements when considering the safety performance of urban arterials. It is crucial to consider geometric design elements, such as median storages, driveways, and other elements, as a part of a larger system rather than isolated elements, so as to provide safer arterials near freeway interchanges.