<Tr> <Td> Line 1 </Td> <Td> 24 October 1984 </Td> <Td> 10 July 2013 </Td> <Td> 24 </Td> <Td> 27.22 </Td> <Td> Noapara </Td> <Td> Kavi Subhash </Td> <Td> 27 trains </Td> <Td> 1,676 mm (5 ft 6 in) </Td> <Td> 750 V DC using third rail </Td> </Tr> <Tr> <Td> Line 1 extension </Td> <Td> June 2019 </Td> <Td> </Td> <Td> 03 </Td> <Td> 4.11 </Td> <Td> Dakshineswar </Td> <Td> Noapara </Td> <Td> </Td> <Td> 1,676 mm (5 ft 6 in) </Td> <Td> 750 V DC using third rail </Td> </Tr> <Tr> <Td> Line 2 </Td> <Td> October 2018 (Sector V to Salt Lake Stadium), Phoolbagan March 2019, Complete route June 2021 </Td> <Td> </Td> <Td> 12 </Td> <Td> 31.55 </Td> <Td> Howrah Maidan </Td> <Td> Salt Lake Sector V </Td> <Td> </Td> <Td> 1,435 mm (4 ft 8 ⁄ in) </Td> <Td> 750 V DC using third rail </Td> </Tr> <Tr> <Td> Line 3 </Td> <Td> December 2019 (Joka - Majerhat) </Td> <Td> </Td> <Td> 12 </Td> <Td> 17.75 </Td> <Td> Joka </Td> <Td> B.B.D Bagh </Td> <Td> </Td> <Td> 1,676 mm (5 ft 6 in) </Td> <Td> 750 V DC using third rail </Td> </Tr>

When was the first underground metro railway started