connect Maharashtra to six neighbouring states. The state's national highways are long. Maharashtra also has a large state-highway network; in March 2018, 99.5 percent of the state's villages were connected by all-weather roads. The Yeshwantrao Chavan Mumbai-Pune Expressway, India's first controlled-access toll road, becamee fully operational in April 2002. The Maharashtra State Road Transport Corporation (MSRTC) has been providing public-sector road passenger service since 1948, linking most of the state's towns and villages in a large network. These buses, popularly known as ST (State Transport), are the preferred mode of transport for much of Maharashtra's population. In addition to the government-run buses, private luxury buses serve major population centres. Other modes of public road transport, such as the seven-seat Tempo, have become popular in semi-urban areas. Railways Rail transport is primarily provided by Indian Railways, part of the Ministry of Railways and divided into eighteen zones. IR is sub-divided into sixty-seven divisions, each with a divisional headquarters. Maharashtra is connected to other parts of India with a rail network, and contains many IR zone and division headquarters: IR's Central and Western Railway zones are headquartered in Mumbai at Chhatrapati Shivaji Terminus (CSTM) and Churchgate, respectively. Nagpur Junction houses the Nagpur and divisions of the Central and South East Central zones, respectively. The Nanded division of the South Central Railway zone, which serves Maharashtra's Marathwada region, and The Konkan Railway, an IR subsidiary based in CBD Belapur, Navi Mumbai, which serves the Konkan coastal region and continues down the country's west coast. The Mumbai and Pune Suburban Railways carry about 6.4 million passengers daily. Maharashtra also has metro and monorail networks. Mumbai Metro is operational, and metros in Nagpur, Navi Mumbai, Nashik and Pune are under construction. The Greater Nashik Metro, being built by Maharashtra Metro Rail Corporation Limited, is planned to connect the city with suburban areas such as Nashik Road, Nashik Airport and Sinnar. Mumbai Monorail is operational, and Pune Monorail is proposed. Mumbai had tram service until 1964, when it was replaced by expanded bus service. A rail tunnel under the sea is planned. It will link the UAE with the western coast of India. The tunnel will be supported by pontoons and will be nearly 2000 kilometres in length. Air Civil aviation in Maharashtra began in the 1920s with Juhu Aerodrome, one of India's first and a base for J. R. D. Tata's Tata Airlines during the