The Relationship between Bicycle Accidents and Lanes of Travel at Downtown Ann Arbor Intersections
Hyeyun Lee
Masters of Urban Planning Student
University of Michigan
Taubman College of Architecture and Urban Planning
The material in this article represents an accumulation of material related to bicycle issues found within the archives of the University of Michigan.  In the summer of 2002, the author will be an intern for the Environmental Coordinator of the City of Ann Arbor, during which time she will have an opportunity to work the current situation in a real-world setting.

The methodology involved the steps listed below, as well as others (see for the full project): 

    • View bicycle-accident map: specifies where bicycle accidents occurred. Select the intersections to study. The number of accidents that occurred from 1983 to 1992 were tabulated at each of those intersections (source:  John D. Nystuen for Ann Arbor Police Department data).
    • A brief survey was conducted at each intersection to calculate:
    • The number of lanes of traffic in each direction.
    • The angle of the intersection (at 6-way intersections, the angles were averaged.)

Animated map showing locations and numbers of bicycle accidents (scroll over on low-resolution settings to see the entire map).

Click here to see the interactive map.

Bike Accidents 
  • 794 bike accidents happened in Ann Arbor from 1983 to 1992.
  • Buffers are around every intersection and the radius is 0.02 mile. (The radius on the above map is 0.04 mile to show buffers better on the web.)
Bike Lanes (suggested by the Park and Recreational Department of City of Ann Arbor, in June 2001). 
  • Bike Lane: On-road travel lane designated for the exclusive use of bicycles.
  • Designated Bike Route: Road designated by green “Bike Route” sign, which has either wide outside curb lane or low traffic volume.
  • Suggested Bike Route: Road which has either wide outside curb lane or low traffic volume.
  • Shared-use Path: Off-road paved path for non-motorized use.
  • Sidewalk: Off-road facility bordering a roadway



Animated map showing accidents by season (scroll over on low-resolution settings to see the entire map).
Spring(Mar, Apr, & May): 162 accidents, Summer(Jun, Jul, & Aug): 276 accidents, Fall(Sep, Oct, & Nov): 282 accidents, and Winter(Dec, Jan, & Feb): 43 accidents


The information here serves as a baseline.  It is presented in animated and interactive formats to see change over time.  Current information will add to it and offer directions for analysis that respond to contemporary needs.

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