Shutting down roads won't reduce the amount of walking people would have to do since it doesn't magically uproot the stores and homes that already exist. My dentist or my grocery store are still a half mile away regardless of the number of streets I have to cross in the middle. And if you're only closing one out of every four roads, that leaves 75% that people will still have to cross. If you have trouble crossing streets, you're still going to have trouble crossing streets.