Bicyclist and Motorist Behavior at Bike Boxes

Bike boxes provide a designated space for bicyclists to gather at the front of the traffic queue and are intended to generally improve the visibility and predictability of their positions. Multiple bike box studies have been performed over the past 10 years in the United States, yet the impact of bike box design on motorist and bicyclist behavior is not well understood. This paper presents a field study that assesses motorist and bicyclist behavior at 11 bike boxes in Boston and Somerville, Massachusetts. Motorist behavior was assessed based on motorized vehicle encroachment on the bike box by vehicles arriving during the red signal. Bicycle behavior was studied by recording the positioning of bicyclists during the red signal. The study results indicate lower motorist compliance rates compared with previous studies and confirm the correlation between compliance rate and turning movement that had been previously reported in the literature. Motorists' compliance could not be correlated with motorized vehicle or bicyclist demand, and only some initial hypotheses were extracted on the impact of bike box design characteristics on motorist compliance that warrant future exploration. Bicyclist behavior with regard to positioning within the bike box was comparable with earlier studies. Overall, this study reinforces the need for further research to understand user behavior at bike boxes and relate behavior to safety outcomes as well as the need for outreach and education efforts to support bike box effectiveness.