Some Operational Features in Bicycle Traffic Flow

Abstract

This study investigated the operational features in bicycle traffic flow on bicycle-only paths. A field investigation was conducted on four bicycle-only paths in the vicinity of bottlenecks in the city of Nanjing, China; two were one-lane paths and two were two-lane paths. The cumulative curve method was used to extract from videos traffic flow information, such as bicycle speeds, flow, and density. The fundamental diagram with free-flow and congested traffic state was constructed with the use of actual traffic data. Data analysis showed that the capacity of bicycle traffic flow on the one-lane and two-lane paths was 3,960 bicycles per hour and 8,100 bicycles per hour, respectively. The critical density was approximately 100 bicycles per kilometer per lane. Average bicycle speed and speed variation decreased as bicycle density increased. The probability of overtaking was highest when bicycle traffic was slightly congested. The observational study showed that even when average speed was quite low, bicycle traffic could still maintain a relatively large flow. This differed from the results of simulation studies. The findings of this study can help traffic engineers better understand the features of bicycle traffic flow and propose measures to improve bicycle operations.