Question: How many kilometres are being built underground of the tunnel in the country that is 450,295 square kilometres ?

text: List of longest tunnels
World 's longest tunnels ( under construction )

This list of longest tunnels ranks tunnels that are at least 13 km (43,000 ft) long. Only continuous tunnels are included. Pipelines, even those that are buried, are excluded. The longest tunnels have been constructed for water distribution, followed by tunnels for railways.
Type Name Location Length Year Comment
Water Supply Yunnan-Guizhou Water Tunnel Yunnan , China 661,000 m ( 410.7 mi ) 2025 Inter river basin water transfer
Water Supply New York City Water Tunnel No . 3 New York State , United States 96,560 m ( 60.0 mi ) 2020 More water supply for New York City . Already in use ; at completion it will be the world 's third longest tunnel
Metro Paris Metro Line 15 Paris Petite Couronne , France 75,000 m ( 46.6 mi ) 2022-2030 Circular line ; will form the longest subway tunnel
Metro Bolshaya Koltsevaya line Moscow Metro , Russia 69,000 m ( 42.9 mi ) 2018-2023 Circular line
Railway Twin Tube Brenner Base Tunnel Stubai Alps , Austria - Italy 55,000 m ( 34.2 mi ) 2028 Construction started in March 2015 . Together with the already constructed Inntal Tunnel it will form the world 's longest continuous railway tunnel with 64 km
Metro L9 / L10 Barcelona , Spain 43,710 m ( 27.2 mi ) 2009-2016 ( partially ) The total system will have a length of 47.8 km , of which 43.71 km is underground and 4.09 km is on viaducts . Northern section of the line is in operation since 2009-12-13 . Southern section of the line is in operation since 2016-02-12 . Future of central section is unclear
Metro Mass Rapid Transit ( Singapore ) : Thomson-East Coast Line Singapore , Singapore 43,000 m ( 26.7 mi ) 2024 Excluding planned extension
Mineral transportation Woodsmith Mine Tunnel Potash Project Mineral Transport System ( MTS ) North York Moors , United Kingdom 36,700 m ( 22.8 mi ) 2021 6 m in diameter incorporating conveyor and maintenance access . Start of construction was planned for 2016 , but actually started in April 2019
Railway Gaoligongshan Tunnel Yunnan , China 34,586 m ( 21.5 mi ) 2022 Railway between Dali and Ruili . Construction started in August 2017
Railway Twin Tube Koralm Tunnel Koralpe , Austria 32,900 m ( 20.4 mi ) 2025 Part of Koralm Railway ; boring of main tunnel started at the west portal May 2010
Railway Twin Tube Semmering Base Tunnel Lower Austria / Styria , Austria 27,300 m ( 17.0 mi ) 2026 Construction of the first contract section started January 2014 . Will cut travel time between Vienna and Graz by 30 minutes and is part of the Baltic-Adriatic Corridor
Road Rogfast Harestad - Arsvågen , Norway 26,700 m ( 16.6 mi ) 2026 Construction started in January 2018 . Will be the longest road tunnel in the world , and also the deepest undersea tunnel , 392 meters below sea level
Water Supply Melamchi Water Tunnel Melamchi to Kathmandu , Nepal 26,000 m ( 16.2 mi ) 2015 ( ? ? ) Under construction , financed by Asian Development Bank
Railway Musil Tunnel Wonju - Jecheon ( Jungang Line ) , South Korea 25,080 m ( 15.6 mi ) 2018 Work slated to start June 2011
Railway Twin Tube Pajares Base Tunnel Principado de Asturias and León , Spain 24,667 m ( 15.3 mi ) ( ? ? ) Breakthrough 2008 ; opening date in question due to severe water leakage and lowering of local water tables
Water Supply Mae Taeng-Mae Ngat Tunnel Chiang Mai , Thailand 25,624 m ( 15.9 mi ) 2021 4.00 m in diameter . This tunnel is a part of Mae Taeng-Mae Ngat-Mae Kuang Diversion Tunnel Project
Water Supply Mae Ngat-Mae Kuang Tunnel Chiang Mai , Thailand 22,975 m ( 14.3 mi ) 2021 4.20 m in diameter . This tunnel is a part of Mae Taeng-Mae Ngat-Mae Kuang Diversion Tunnel Project
Railway Follo Line Oslo , Norway 19,500 m ( 12.1 mi ) 2020-2021 Groundbreaking 2014
Road WestConnex Sydney , Australia 19,000 m ( 11.8 mi ) 2023 ( 2019 partial completion )
Road Förbifart Stockholm Stockholm , Sweden 16,500 m ( 10.3 mi ) 2030 Construction started in August 2014