Using Simulation to Assess and Reduce Conflicts between Drivers and Bicyclists
Separated bicycle lanes, or cycle tracks, are increasing in popularity across the nation. When the Massachusetts Department of Transportation (MassDOT) became the first DOT to publish a Separated Bike Planning & Design Guide, it provided evidence that separated bicycle facilities are likely to become even more common. Despite documented benefits of separated bike lanes, including safer cycling and increased ridership among differing populations of bicyclists, there remain ongoing concerns about potential conflicts between bicycles and vehicles when they merge back together at an intersection. The fear is that following a period of separation, drivers are less likely to anticipate and scan for the presence of bicycles.
This project will model the interaction between bicyclists and drivers at critical crossing points using microsimulation to identify commonly-occurring conflicts and then instantiate them in simulator scenarios that capture these problematic areas and traffic configurations. These scenarios will then be used to study driver behavior in a driving simulator and bicyclist behavior in a bicycling simulator. The project will evaluate different strategies for integrating bicyclists and drivers following a period of separation and document the specific behaviors that may impact safety. This project will advance understanding of how roadway design influences bicycling safety. The outcomes will inform the development of roadway designs that accommodate mixing of bicycles and motorized vehicles. The results of this study will also inform future work on the design of connected vehicles systems by identifying where this information is most needed.
While there has been a growing amount of support for bike lanes on urban and suburban roadways as levels of bicycling have increased in the United States, the safety issue between drivers and bicyclists has been recognized as one of the critical traffic safety problems recently. According to the National Highway Traffic Safety Administration (NHTSA) , over 900 bicyclists were killed in 2013 in the U.S. and most bicyclist fatalities occurred in urban areas (70%). Moreover, bicyclist deaths occurred most often between 6 p.m. and 9 p.m. (20%). Bicyclists are generally using the shoulder of roadways and simultaneously riding next to vehicles. Therefore, there are higher chances of conflicts between bicycles and vehicles, and a serious injury crash can be occurred due to these conflicts. For this reason, nearly every major city has made an effort in recent years to install bike lanes to provide bicyclists’ own designated path. Since a bike lane is relatively new feature in urban roadway cross-section, implementation of bike lane would be challenging in different traffic conditions and its safety effectiveness has not been well examined.
Thus, there is a desperate need to identify and test roadway countermeasures to improve driver and bicyclist safety particularly for urban areas. In order to explore the safety impact of current roadway geometric designs and infrastructures on mixed traffic condition (i.e., bicycles and motorized vehicles), the research team will conduct comprehensive safety analysis using historical crash data and develop safety performance functions (SPFs) and crash modification factors (CMFs). Furthermore, we will identify additional countermeasures (e.g., bike lane with wide width, physical separations, street lighting, roundabout, complete street, traffic calming techniques, protected intersection, etc.) from national and Worldwide experiences. Based on the results of crash analysis and identified countermeasures, a micro-simulation investigation will be assessed to study the impact of implementing different roadway cross-section designs under complexed urban traffic patterns. The outcomes will provide insights on understanding of how different roadway infrastructures and designs influence driver and bicyclist safety.