Monday, February 21, 2011

New Map Plots Bicycle Accidents In Chicago

If you ever wanted to see where bicycle crashes tend to occur in Chicago now you can.  Urban planner and blogger, Steven Vance, has created an online map pinpointing the location of all 6,369 reported bicycle accidents in the city between 2007 and 2009, the last year for which information is available.  Having gathered crash data from the Illinois Department of Transportation via the Freedom of Information Act, Mr. Vance plotted the bike crash sites on a map generated by Google.  Click here to view the map.

The map is quite interesting.  I was struck immediately by the sheer number of crashes along Milwaukee Avenue, a well-known bike commuter route between the Northwest Side and the Loop.  The data is consistent with my own observations.  During most of the year I tend to get a lot of calls from bicyclists looking for an attorney following a collision with a motor vehicle on Milwaukee.  As Mr. Vance notes, however, it is important not to draw too many conclusions from the crash map.  Lots of collisions along Milwaukee Avenue, for instance, does not mean that the locale is a particularly dangerous place to ride.  It may simply mean that there is a lot of bike traffic there, naturally increasing the opportunities for a bike and motor vehicle to collide.  It may be that roads with fewer red dots are more dangerous; that the number of crashes compared to the number of cyclists using the roadway is higher.  The map doesn't reveal that data.  It also does not suggest the severity of the plotted crashes.    If there are clusters of crashes involving very serious injuries along specific routes, the map does not reveal that.

These limitations are no knock on Mr. Vance's effort, which is laudable.  I point them out to caution the viewer not to jump to conclusions about which routes through the city are safe and which are not.  In an interview with The Bay Citizen, Mr. Vance acknowledged as much stating, "I don't think we can draw many conclusions from this map except to target our infrastructure (new bike lanes, and hopefully some protected or separated bike lanes in some areas) as well as our education efforts for people who bike and people who drive."

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