You’re in the middle of working on your “walk scores” assignment. Note that the walkscore.com website includes travel time maps, which show how far you can get in any direction from a particular address in a given amount of time. Maps based on this idea of isochrony go back at least to the 1880s, and sometimes covered whole countries or the world, as described in this Atlas Obscura article: “Traveling Back in Time With Colorful Isochrone Maps.”