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  • chicago_traffic_tracker_historical_congestion
Updated 10 months ago
Indexed 1 hour ago

Chicago Traffic Tracker - Historical Congestion Estimates by Segment - 2011-2018

This dataset contains the historical estimated congestion for 1270 traffic segments, in selected time periods from August 2011 to May 2018. Newer records are in The most recent estimates for each segment are in

The Chicago Traffic Tracker estimates traffic congestion on Chicago’s arterial streets (non-freeway streets) in real-time by continuously monitoring and analyzing GPS traces received from Chicago Transit Authority (CTA) buses. Two types of congestion estimates are produced every 10 minutes: 1) by Traffic Segments and 2) by Traffic Regions or Zones. Congestion estimates by traffic segments gives observed speed typically for one-half mile of a street in one direction of traffic. Traffic Segment level congestion is available for about 300 miles of principal arterials. Congestion by Traffic Region gives the average traffic condition for all arterial street segments within a region. A traffic region is comprised of two or three community areas with comparable traffic patterns. 29 regions are created to cover the entire city (except O’Hare airport area). There is much volatility in traffic segment speed. However, the congestion estimates for the traffic regions remain consistent for a relatively longer period. Most volatility in arterial speed comes from the very nature of the arterials themselves. Due to a myriad of factors, including but not limited to frequent intersections, traffic signals, transit movements, availability of alternative routes, crashes, short length of the segments, etc. Speed on individual arterial segments can fluctuate from heavily congested to no congestion and back in a few minutes. The segment speed and traffic region congestion estimates together may give a better understanding of the actual traffic conditions. Current estimates of traffic congestion by region are available at


NameSocrata field nameColumn name in sgr mountData typeDescription
SPEEDtraffictrafficNumberReal-time estimated speed in miles per hour. For congestion advisory and traffic maps, this value is compared to a 0-9, 10-20, and 21 & over scale to display heavy, medium, and free flow conditions for the traffic segment. Segments which has insufficien
BUS COUNTbus_countbus_countNumberNumber of buses providing a GPS feed used to estimate congestion.
MESSAGE COUNTmsg_countmsg_countNumberNumber of GPS probes received(or used) for estimating the speed for that segment.
TIMElast_updatelast_updateCalendar dateDate and time corresponding to congestion estimate.
SEGMENTIDsegment_idsegment_idNumberUnique ID for each segment. See for the geographic location of each segment.
Upstream Metadata