After the earthquake of March 2011, millions of people had difficulty returning home. For a large number this was unrelated to the problems of the gridlocked roads or suspended rail service and much more to do with they simply didn't know where they lived. Many people live on the subway and rarely see the world between their home and work; they just didn't know where to go.
I started to walk home a couple of times a week, a distance of around 8km (5 miles), just for the exercise and suddenly discovered a Tokyo I'd never seen before as I took routes through backstreets and alleyways, keeping clear of the main roadways. Walk home, it's fascinating, healthy and you'll know where to go in an earthquake.