The Mumbai Suburban Railway consists of rapid transit on exclusive inner suburban railway lines augmented by commuter rail on main lines serving outlying suburbs to serve the Mumbai Metropolitan Region. Spread over 465 kilometres (289 mi), 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 the busiest rapid transit system in the world.