Sometimes extreme congestion of commuter trains can become a problem. For example, an estimated 3.5 million passengers ride every day on Yamanote Line in Tokyo, Japan, with its 29 stations. For comparison, the New York City Subway carries 5.7 million passengers per day with stations. Special cars have bench seats fold up to provide standing room only during the morning rush hour on this line. In the past this train has included 2 cars with six doors on each side to shorten the time for passengers to get on and off at station.