The Mass Rapid Transit, abbreviated and referred to in local parlance as the MRT, is a heavy rail rapid transit system that constitutes the bulk of the railway network in Singapore, spanning—with the exception of the forested core and the island's rural northwest—the length and width of the city-state's main island. Singapore's heavy rail network is composed of four distinct systems. The first section of the MRT opened on 7 November 1987, and the network has since grown rapidly in accordance with Singapore's aim of developing a comprehensive rail network as the backbone of the country's public transportation system, with an average daily ridership of 3.384 million in 2019, approximately 83% of the bus network's 4.099 million in the same period.