Transit Time and Efficiency Maps: Method
The original purpose of our project was to create heat maps of transit times from a fixed point in Chicago all throughout the city. The maps in this section of the site start from Madison and State in the Chicago Loop. Like the maps we've made of the recent transit cuts, these maps show times for the morning, and for the late night.
In addition to heat maps of transit times, we've also made maps of transit efficiencies, by dividing through travel time by taxicab distance. We used taxicab distance rather than birds' eye distance because Chicago's grid has a greater impact than straight lines on the perception of distances in this city. A neighborhood's proximity to another is, on the Chicago grid, a function of "up and over" rather than "as the crow flies". So it seemed natural to measure public transit efficiency using this as the baseline.
(One interesting note: efficiency is the same or higher in the morning everywhere except the southwest side. This is because we measured inbound in the morning and outbound at night. The orange line happens to travel clockwise around the loop, so it's quicker to get out than in if you're in the eastern part of the loop.)