This map could not have existed a few years ago:
.
.
It shows how many jobs are accessible within 30 minutes from each location by public transit in Minneapolis/St. Paul during the 7-9 am peak morning window. The darker green areas have the greatest accessibility to jobs; the lighter green areas have the least. The red lines show transit routes.
It is built with three key datasets: GTFS data from the local transit agency; OpenStreetMap data on pedestrian routes and walking times; and block-level job counts from the Census Bureau. The first two data sets did not exist a few years ago.
Why is this important? Because it distinguishes between mobility and accessibility. Guess which is more important? And guess which one gets the most attention?
Emily Badger explains in Atlantic Cities:
Every year, the Texas A&M Transportation Institute releases an oft-cited (and oft-critiqued) Urban Mobility Report that measures congestion on American roads, famously ranking the metros with the most heinous traffic. The report homes in on a central cost of mobility: the price we pay to sit in gridlock.
It does not, however, look much at the value we get for paying that cost: access to wherever we’re trying to go. …
Consider a metric – or a map – that captures value instead. Not: How long will it take me to reach my office? But: How many jobs can I reach in half an hour? How many grocery stores are accessible by car within five minutes? Which neighborhoods in town enable the greatest accessibility, by public transit, to really good restaurants?
More explanation and maps here, and how they can be used for research and planning.
