Interestingly, one practical tactic for increasing walkability in cities is to focus on increasing the re-usability of parking. People who live in an apartment and drive to work don't need their parking space during the day, so sometimes you can have an apartment and an office share parking spaces, in the middle of a city. Obviously there's nowhere near 100% overlap, but if you can get to a situation where you only need 150% as much parking instead of of 200%, that's great.