Category Archives: Visualization

Chicago Transit Accessibility 7–9 AM (Video)

Accessibility to jobs by transit for every Census block in the Chicago metropolitan area, between 7 and 9 AM. Based on CTA, Metra, and Pace schedules from January 2014.

Lighter colors indicate few jobs can be reached within 30 minutes; darker colors indicate more jobs can be reached within 30 minutes. At the highest levels, millions of jobs are accessibility by transit within 30 minutes. Travel times include walking, waiting, riding, and transfers.

Data sources: US Census Bureau, Chicago Transit Authority, Regional Transportation Authority, OpenStreetMap.

This is work of the University of Minnesota Accessibility Observatory.

Intersection of Oak and Fulton Streets, SE Minneapolis

Time to walk: A brief excursion into a needless incursion on the law-abiding pedestrian’s time

The traffic signal at Oak St. SE and Fulton St. SE in Minneapolis is mis-timed/mis-phased/mis-indicated. It has been so for several years.

Northbound Pedestrians on the west side are given a red indicator (Don’t Walk) even though Southbound traffic has a green light and green left turn arrow. Clearly Northbound Pedestrians on the east side of the intersection should have a red indicator in such a configuration, as they are in conflict, just not those on the west side.

We can imagine why this might have occurred, but basically the walk signals are tied together even though vehicle traffic has a split phase. Obviously the technology exists so this is not necessary. This occurs from the 0:36 to the 0:49 mark in the video below. It’s “only” 13 seconds of course, but we could say the same about vehicle delays. It’s 13 seconds every minute of every day for every pedestrian at the intersection. This is near the University of Minnesota campus so the number of pedestrians is non-zero. In late spring it’s not an unpleasant wait. Talk to me in January.

Video (looking SB on Oak Street, East on the left, West on the right):

How often does this occur? Where else do the traffic engineers not think through the implications for pedestrians?

I cannot comment on what the optimal traffic signal timings are for this intersection, but this is clearly not it.

Further reading:

One day of the Divvy bicycle-share system

Published on Mar 6, 2014
This video (best watched in high-definition (HD 720p)) shows all the bicycle trips made in one day in Chicago’s Divvy bicycle-share system, 2013. Each circle represents a Divvy bicycle station. Larger circles indicate a greater number of trips beginning and ending at that station. The color of the circle indicates the proportion of trip arrivals and departures: yellow means more arrivals, pink means more departures, and white means an equal mix of both. Watch the pattern of colors in the morning rush hour.

The number of arrivals and departures at each station was calculated for every five-minute interval of the day and was averaged over the number of days that the station was active in 2013.

This video was produced by Colin J Stewart (, an urban-planning graduate student at Transportation Research at McGill (TRAM: Check out my previous video of Montreal’s public transit system:…

The music in this video (“The Koto Chill”) was written by Zircon ( If you like this track, check out his other work.

Data was provided by Divvy Bikes ( as part of their 2014 data challenge. Big thanks to Divvy!

Forcing a round object into a square map

The earth is approximately a sphere, yet we try to force this round object into a square grid through the use of latitude and longitude and Ordinance Surveys. Why?
The rationale for use of grids depends on scale. We have naturally come to think of the earth rotating on an axis with a prime meridian reflecting that access on the surface, intersecting the axis at the north and south poles, complemented by an equator belting it. The equator has a natural physical meaning, but the prime meridian is arbitrary. Greenwich, England is no more the start of time than any other place. But longitude, if not latitude is arbitrary. The idea of longitude lines running north-south does have convenience in that it tends to align with the magnetic poles, and benefitting navigation.


Geodesic domes, developed by Buckminster Fuller (who did not invent soccer, but whose name was given to the Fullerene) enclose spherical areas with a mesh of triangles, forming many hexagons and 12 pentagons.
We could remap the earth using geodesic principles. Fuller did this with his Dymaxion Map. The triangular cut marks do not align with latitude and longitude. However, one should be able to align the triangles with either latitude (the equator) or longitude (a prime meridian), though that might cut land masses, which dilutes the political point Fuller was trying to make.

There are many ways to skin the earth, and stretch it out like a tanner stretches leather. The way we present this 3D object in 2D affects how we perceive it. We expect (in western countries) north to be up, and are disoriented when maps are presented otherwise. Yet we don’t expect our environment to clue us in very often, we don’t typically see compass marks in the pavement to show us which direction is north, to help us reorient (meaning turn to the east, oddly we never reoccident and turn to the west).
The map is the user interface to the environment, and we need to give it more consideration. We should also better embed navigation clues into our environment. Some cities post wayfinding systems around, especially near transit stops. Even (especially?) in the age of the almost ubiquitous smart phone, this still seems wise, so people can keep their eyes looking ahead, focused on the real environment, rather than face down in a phone, or staring into an imaginary distance with glasses.