Sometimes extreme congestion of commuter trains becomes a problem. For example, an estimated million passengers ride every day on Yamanote Line in Tokyo , Japan, with its 29 stations. For comparison, the New York City Subway carries million passengers per day on 25 services serving 472 stations. To cope with large traffic, special cars in which the bench seats fold up to provide standing room only during the morning rush hour (until 10 .) are operated in Tokyo ( E231 series train). 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.