The intersection of Grand/Milwaukee/Halsted has the third highest incidence of collisions between automobiles and bicycles at Milwaukee Avenue intersections. Will bicycle crash data help city planners focus their attention on improving safety at the spots with the most frequent crashes? 

I recently obtained from the Illinois Department of Transportation (IDOT) the 2010 vehicle crash data, which includes collisions between automobile drivers, bicyclists, pedestrians. I plan to update the Crash Portal with this information. But I also plan to do something more than make a map; Derek Eder*, myself, and others will dig deeper into the data to see what story we can tell with it. We’ll do that in addition to listing and visualizing statistics that citizen cyclists are more accustomed to, like the change in crash rates year after year.

So what happened in 2009?

In 2009, there were 1,484 reported crashes involving bicyclists. Six bicyclists died in these crashes.

IDOT will not be reporting dooring crashes prior to 2010; it’s unclear if they even collected this information prior to 2010.

And what’s happened in 2010?

In 2010, there were 1,643 reported crashes involving bicyclists. Five bicyclists died in these crashes.

When I posted this on my personal Twitter on Tuesday, someone asked, “Is the increase because of doorings?”

Good question and I didn’t know the answer. But I would quickly find out, by asking IDOT, that the crash dataset does NOT include instances of doorings – those are listed in a separate report and the datasets are exclusive of each other. That report, which you can access yourself after receiving the login credentials from IDOT, shows 127 reported doorings.

Add this to the non-dooring crashes and there were 1,770 reported crashes involving bicyclists.

It’s important to know that Active Transportation Alliance, Jon Hilkevitch at the Chicago Tribune, and possibly my own blogging, prompted Governor Quinn in April 2011 to direct IDOT to collect and report information about dooring-type crashes.

What about doorings in 2011?

I checked the report online Tuesday, September 6, 2011, and data was current up until August 8, 2011. There were 164 reported dooring crashes in that time period. This year is on track to see more reporting dooring crashes than last year. This could indicate that 2011 will also have more reported crashes than 2010. If that rate continues (0.75 reported doorings per day), then 2011 will see 273 doorings, or more than twice as many as were reported in 2010.

You can avoid being doored by watching for people in cars (which could mean they may be getting out of the car) and ride outside the door zone. The door zone is equal to a width of an open car door. This may mean the entire width of many bike lanes in Chicago!

Mockup of a pavement marking that might appear in the bike lane to warn bicyclists of the door zone. Photo by Gary Kavanagh. 

Would these markings in the bike lane encourage bicyclists to ride outside the door zone? San Francisco hopes to find out in this experiment. What can we do to reduce the incidence at crashes where they most often occur, at intersections? See photo below. Photo by Lee Dennis.

Why the increase between 2009 and 2010?

The first explanation I proffer is that more crashes are being reported than before. Perhaps people are convinced of the value in reporting crashes (I doubt this, as it’s hard to explain with sufficient persuasion). There is no research that can validate this.

The second is that more people are bicycling in 2010 than 2009 and while road users are adjusting to each other’s presence, the crash rate rises with the bicycling rate. However, we have no data yet, or even a dataset acting as a proxy, that reports on ridership in Chicago in 2010. There is data for 2009, but it only reports on people 16 and older who bicycle to work (from the American Community Survey). I’ve written on Steven Can Plan about this need for more information on bicycle ridership, research that goes beyond information about the journey to work, and that includes information about all the reasons for trips people make (shopping, social, school, etc.).

To reduce the incidence of the most common location and moment of crash, during a turn at an intersection, Chicago planners could adopt many of the features they first implemented in the Kinzie Street protected bike lane. These features were inspired by the National Association of City Transportation Officials’ (NACTO) “Urban Bikeway Design Guide.” Chicago is a founding member of NACTO. 

Notes on the data

Data in this post may be different than that found in the data table that supports the first bike crash map. This is because I now have the full dataset from IDOT and I’m creating my own database join, which may be different than the method IDOT used to create its “pedalcyclist extracts.” I do this because the method IDOT uses left out one bicyclist fatality in 2009 because the bicyclist was not the first point of impact in the crash.

I join the Crash and Persons table based on their common field of “casenumber.” I search the Persons table for a Person Type of “3″ (pedalcyclist). With the resulting casenumbers, I then search the Crash table. This method returns ALL crashes in which pedalcyclists were involved, whether or not they were the first point of impact in the crash.

I am not allowed to share the complete dataset with anyone – each researcher has to individually accept the privacy laws that controls the release of this data. You can obtain the dataset yourself from IDOT. If you are interested in a project on bicyclist or pedestrian crash data, I will help you obtain it. You may ask me for the exact queries I used to extract the figures in this article.

*Derek and I worked on the crash data after I created the first Chicago bike crash map.