When you live in Tokyo, you spend a fair amount of your life on trains. This is what happens when you live in a place with a very convenient, efficient, and punctual public transport system and very expensive parking. After the March 11, 2011 earthquake, my feeling about stepping onto a train changed. The trains automatically stop when a strong quake happens. If you are stuck on one between stations when one hits, it could be hours before you get out. They can't exactly open the doors in the middle of nowhere and have you disembark because the train platforms are very high (4.5-5.5 ft.) and there's no way to get down when you're not at a station short of a special ladder. In California, you go up steps to get on the train. In Japan, not so much. I talked to some people who were trapped on trains for as long as three hours during the quake and the answer to "what happens if you have to go to the bathroom" (as there are none on standard trains and subways). The answer was a shoulder shrug.
After the big quake, I was always afraid of being trapped for hours on a train or subway after a big quake and ending up soiling myself and I won't miss that paranoia.