Mumbai Suburban Railway consists of exclusive inner suburban railway lines augmented by commuter rail on main lines serving outlying suburbs to serve the Mumbai Metropolitan Region. Spread over , the suburban railway operates 2,342 train services and carries more than 7.5 million commuters daily. By annual ridership (2.64 billion), the Mumbai Suburban Railway is one of the busiest commuter rail systems in the world. It has some of the most severe overcrowding in the world. Trains run from 4 AM until 1 AM, and some trains also run up to 2:30 AM.