Traffic Impacts of Bicycle Facilities

Principal Investigator:

Greg Lindsey, Professor, Humphrey School of Public Affairs


  • John Hourdos, Director, MN Traffic Observatory, Civil, Environmental and Geo-Engineering

Project Summary:

Federal, state, and local policies such as Complete Streets encourage multi-modal planning and the design of roadways and streets to accommodate bicyclists and pedestrians as well as motor vehicles. As roads are resurfaced, county and municipal engineers have opportunities to restripe and change lanes provided for vehicles, bicycles, and parking. Engineers have implemented a variety of innovative multimodal designs, but few of these designs have been evaluated. County and municipal engineers have identified gaps in the technical guidance for multimodal facilities associated with the lack of evaluation. For example, the AASHTO Guide for the Development of Bicycle Facilities (AASHTO 2012), the NACTO Urban Bikeway Design Guide (NACTO 2011), and the MnDOT Bikeway Facility Design Manual (MnDOT 2007) do not provide guidance on travel lane widths in combination with bike lanes, and none provides guidance on the effect of lane width on vehicle speeds in shared facilities. The Highway Capacity Manual (HCM) acknowledges that bicycles have an effect on traffic and assigns Passenger-Car Equivalent factors on bicycles ranging from 0.5 to 1.2 cars based on total lane width, but the HCM does not relate these numbers to any of the particular bicycle lane designs. Gaps in existing guidance documents related to the effects of bicycle lanes on vehicular traffic speed, vehicular displacement, and safety can be filled with evaluations of recent innovative designs. This research will identify gaps in technical guidance documents related to design and evaluation of multimodal facilities, complete field observations of traffic flows on multimodal facilities, and document changes in traffic flows and patterns, indicators of safety, and other performance indicators. Benefits to county and municipal engineers will include increased understanding of policies and designs to increase safety and efficient operations for all traffic modes.


Project Details: