16-04 Effectiveness of Bicycle Signals for Improving Safety and Multimodal Mobility at Urban Intersections

With the dramatic increase of non-motorized transportation users, more people are concerned about the non-motorized traffic safety. Unfortunately, bicyclists and pedestrians are prone to more severe injuries when involved in a crash. For bicycle crashes, failing to yield/disregarding traffic control device, and lack of non-motorized facilities were identified to be the main causes of bicycle crashes in urban intersections. This research investigated the effectiveness of two bicycle crash countermeasures with bicycle signal treatments at urban signalized intersections. These two countermeasures are the bike boxes and the protected intersections. The bicycle signal treatments that were tested simultaneously with these countermeasures are the leading bicycle interval and the exclusive bicycle phase. A before and after bicyclist survey was conducted to measure bicyclist perception of safety of the bike box and bicycle signal heads. Additionally, these engineering countermeasures were evaluated from both traffic operation and traffic safety prospective in a virtual test environment built in VISSIM. Users delay were compared before and after implementing these countermeasures. While a surrogate safety measure “conflicts” among users was used to measure the safety impact of such treatments. Through performing benefit-cost analysis, the threshold values of traffic and bike volumes that are needed to justify the bike box and the protected intersection treatments were found. This research also provided a general guideline that can be used by the decision makers to facilitate bicyclist left turn movement at urban signalized intersections