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Crash Data

This is a list of links to the motor vehicle crash data used to power the Chicago Crash Browser created by Steven Vance. The data was provided by the Illinois Department of Transportation's Division of Traffic Safety.

Some datasets have data for crashes within the City of Chicago and others have crashes for the entire State of Illinois.

IDOT Disclaimer

The Division of Traffic Safety requires the following statement be placed on any work product that incorporates or references our data. DISCLAIMER: The motor vehicle crash data referenced herein was provided by the Illinois Department of Transportation. The author is responsible for any data analyses and conclusions drawn.

IDOT will not provide access to its Safety Portal unless you work for a government agency. When I requested access to it in December 2015, Ken Martin from IDOT responded: "The IDOT Safety Portal was designed under the provisions of the Illinois Vehicle Code to provide access to crash data and our SR1050 crash reports for federal, state, and local governmental agencies involved in highway safety research and studies. We will not be able to grant your request." I guess only government agencies have the need for this kind of information.

The Safety Portal replaced the Safety Data Mart in 2016, which had maps and crash data open to anyone.

IDOT has an unpublished ArcGIS MapServer for the Safety Portal. This is the 2017 endpoint. See the section "Extracting data from the ArcGIS MapServer" below for more details on how to access this programmatically.

Notes / Getting Help

  • Be careful comparing data 2005-2008 and 2009 to present because the reporting threshold changed. In the former period, the data will contain crashes that had no injuries and property damage of at least $500. In the latter period, the data will contain crashes that had no injuries but property damage of at least $1,500. If there was an injury, the data will contain that crash regardless of the property damage estimate.
  • Beware that fields were added and removed for the 2013 & 2014 datasets (and likely future datasets). Until I write about the differences please compare the data dictionaries.
  • Note that some years have crash data for the City of Chicago limits and others for the whole state of Illinois.
  • If you need help understanding this data, you can contact Steven on Twitter.

Data Dictionary

Applicable to 2006-2012

Applicable to 2013-2014

Data Links

The data is zipped CSV files. Most of these don't have the field names. You can add those using the field name files at the bottom.

2005 - City of Chicago

2006 - City of Chicago

2007 - City of Chicago

2008 - City of Chicago

2009 - State of Illinois

2010 - State of Illinois

2011 - State of Illinois

2012 - State of Illinois

2013 - State of Illinois (note changes in Data Dictionary above)

2014 - State of Illinois (note changes in Data Dictionary above)

2015 - City of Chicago

Data was posted on April 16, 2017. I thought I asked for the whole state, but maybe I didn't. I'll try to get those later.

Field Names for 2006-2012

Append these to the top of the CSV data.

Field Names for 2013-2015

Extracting data from the ArcGIS MapServer

Use pyesridump to extract the data into GeoJSON (you should have a fast reliable internet connection before starting this).

This command will tell the ArcGIS server to filter the "CrashReportCity" for "Chicago", and will only return the selected rows (this decreases the time to download all of the data).

While this database is real-time in that some of the latest crashes are in here, not all of the latest crashes are in here. If you are looking for complete data, do not use this database – wait for the annual crash reports, which contain complete and cleaned data.

esri2geojson -f ICN,TotalInjured,OInjuries,AInjuries,BInjuries,CInjuries,CrashInjurySeverity,IsHitAndRun,ContribCausePrim,ContribCauseSec,CrashReportCity,CrashDateTimeText,TotalFatals,FunctionalClassCIS,TypeOfFirstCrash,IsAnyCitation,CrashVehicleCount,AgencyCrashReportNo,IsAlcoholRelated,CISCrashID,AddressNo,HighwayOrStreetName,IntersectionStreets,InvestigatingAgencyName -p "where=CrashReportCity%3D%27Chicago%27" http://ags10s1.dot.illinois.gov/ArcGIS/rest/services/SafetyPortal/SafetyPortal/MapServer/12 idotcrashes_2017_Chicago.geojson