Safety and nonoptimal usage of a protected intersection for bicycling and walking: A before-and-after case study in Salt Lake city, Utah

Abstract

This paper describes a before-and-after case study of a protected intersection in Salt Lake City, Utah. The intersection was completed in late 2015 and represented one of the first examples of a protected intersection design in North America. We analyzed bird’s-eye view video data that was recorded before the intersection was implemented and compared it against video data recorded from the exact same location after implementation. In order to examine changes in intersection usage and behavior, we operationalized safety in terms of the frequency of nonoptimal behaviors demonstrated by active transportation modes. We found that active transportation usage of the intersection has increased since the new configuration, with most of that growth attributable to e-scooter users. There was minimal change in the rates of nonoptimal behaviors by pedestrians. Bicyclists showed mostly decreased rates of nonoptimal behaviors, suggesting improved safety for this mode. E-scooter users, however, demonstrated nonoptimal behaviors at very high rates as compared with other active modes. This case study gives evidence that a protected intersection can have positive effects on active transportation volume and safety in a U.S. context.