I need a visualization tip for showing pedestrian and auto traffic in downtown Chicago


Madison Street over the Chicago River. Pedestrian traffic is very high, and very constrained, near the Metra stations.

Here’s the goal:

Show that pedestrians don’t get sufficient space or time to have a high quality pedestrian experience given that they comprise the largest mode share on streets in the Loop. The trips are highly delayed at traffic signals, pedestrian space is encroached upon because of automobile turning movements, and the sidewalks aren’t wide enough for two-way or even one-way traffic at certain times of the day. It’s possible to build our way out of pedestrian traffic…

Here’s an example data set:

On October 3, 2006, for all of the 24 hours, at 410 W Madison Street, there were 17,100 automobiles counted.

On some day in summer 2007, for 10 hours, at 350 W Madison Street, there were 43,987 pedestrians counted.

The two locations are practically the same as the bridge here prevents more pedestrians or automobiles from “slipping in”.

It’s possible to download the data sets from CDOT’s Traffic Tracker so you can see the whole city on your own map, but you’ll have to do some digging in the source code to find them.

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About Steven Vance

Enthusiast for urbanism, bicycling as transportation, and open data. Building a bicycle culture in Chicago.
  • Matthew Moritz

    I’m not sure that the information you are trying to show is particularly conducive to a GIS visualization with bubbles. Perhaps a simplified, too-scale representation of the space dedicated to vehicles and pedestrians. Not sure where to go beyond that, perhaps Level of Service guidelines for sidewalk widths and crossing times based on pedestrian volume (does such a thing exist?) And then compare that with the level of service. If you’re including intersections at the bridge ends, having a break down of the turning movements would also be useful for showing that perhaps the use of turning lanes is over-providing service to automotive users.

    • http://www.stevevance.net/ Steven Vance

      This is what I was thinking yesterday, and told Eric Fischer (@enf):

      A pair of lines (one for each mode) that have widths and some additional attribute that’s defined by the relationship of the traffic count for that mode with the space dedicated to that mode. In other words, the line would be wider as traffic counts are wider, but would change color or texture based on the width of the way for that mode (for sidewalks, it’s 10-16 feet while roads are 40+ feet).

  • http://transitized.com/ Shaun Jacobsen

    I work on Adams at Riverside Plaza. I always feel this when I get there and leave. There’s a ton of room for the cabs and not a ton for peds. There is a light for crossing ped traffic but its short and infrequent. The cabs usually block it anyway.
    Do you need a graphic or a way to show it on the map?

    • http://www.stevevance.net/ Steven Vance

      See the other comment. I want to communicate the differences in space dedication:
      one group makes up X% of traffic, but gets Y% of space

      • http://transitized.com/ Shaun Jacobsen

        This would look good on a map. Based on the numbers you have wouldn’t this be a pretty rough estimate based on an 80′ street?

        I just drew a graphic, but it would be cool to see this on the map in terms of color lines. I’m not that good at GIS, can’t offer any tips there…

        • http://www.stevevance.net/ Steven Vance

          This is close to what I was thinking.

          Now some will say, “a car is bigger than a person”, which is of course true, but shouldn’t people be treated fairly in their travels? Fairness includes providing a safe, comfortable space in which to conduct that travel, with delays equally shared by all people.

          • http://transitized.com/ Shaun Jacobsen

            Isn’t that the whole problem? Clearly a sidewalk can carry far more people than a larger road. Places like the Loop may be congested for all uses at some times, but a lot more people get around on foot than in a car. Cars here are big and most of the people I personally see driving in the Loop are driving alone in cars for 5+ passengers.

          • http://www.stevevance.net/ Steven Vance


          • http://dannyman.toldme.com/ Daniel Howard

            A car is bigger than a person, but a car travels faster than a person, so a car occupies that bigger space for less time. What is the “flow rate” of an 8′ vehicle lane vs a 2′ pedestrian lane?

          • http://www.stevevance.net/ Steven Vance

            This is where I didn’t excel in planning school…

        • http://www.stevevance.net/ Steven Vance

          Can you add a bike lane? I wish I knew the bike traffic counts here.

          • http://transitized.com/ Shaun Jacobsen

            Is there an existing bike lane? I can get that done tonight (dont have AI at work)

          • http://www.stevevance.net/ Steven Vance

            Nope. The existing bike lane on Madison Street ends at Wacker (dumb).

            Also dumb: The bike lane on Madison Street will be removed for Central Loop BRT. A cycle track of some kind (with CDOT’s re-definition game they’re playing I now don’t know what they’re actually doing) will be installed on Randolph Street. Why is that dumb? People will still be bicycling on Madison Street, they’ll just now be doing it in the bus lane.

          • http://transitized.com/ Shaun Jacobsen

            Huh. I notice the fragmented/sudden-ending bike lanes when the street suddenly narrows, but the streets in the loop are all basically the same size. Maybe it’s the bridge.
            This has a 5′ bike lane, 7′ rightmost lane (taxi stands?) and 11′ center lanes.

  • Joseph Musco

    I think you are saying 1 pedestrian = 1 driver but the fluid dynamics of the systems (sidewalks vs. roads) are inefficiently optimized for the far smaller number of drivers.

    Here is a study with some cool images of pedestrians in flow. Figure 4 is excellent. Maybe you can find some inspiration within.


    • http://www.stevevance.net/ Steven Vance

      I think that’s exactly what I’m saying! Now how can I demonstrate that?

  • http://www.facebook.com/reneeprisble Renee Prisble

    could you have a clickable location that switches to a graph based on an elevation view? The graph would have three columns based on the allotted width of each throughway – road, bike lane, and sidwalk, then you could visially stack the users on top of eachother within their space.