List of longest tunnels

Columns: Type | Name | Location | Length | Year | Comment
Water supply | Delaware Aqueduct | New York State , United States | 137,000 m ( 85.1 mi ) | 1945 | 4.1 m wide . New York City 's main water supply tunnel , drilled through solid rock | Water supply | Päijänne Water Tunnel | Southern Finland , Finland | 120,000 m ( 74.6 mi ) | 1982 | 16 m cross section | Water supply | Dahuofang Water Tunnel | Liaoning Province , China | 85,320 m ( 53.0 mi ) | 2009 | 8 m in diameter ( 50m cross section ) | Water supply | Orange-Fish River Tunnel | South Africa | 82,800 m ( 51.4 mi ) | 1972 | Longest continuous enclosed aqueduct in the southern hemisphere ( 22.5 m cross section ) | Water supply | Bolmen Water Tunnel | Kronoberg / Scania , Sweden | 82,000 m ( 51.0 mi ) | 1987 | 8 m cross section | Hydroelectric | Neelum Jhelum HydroPower Tunnel | Muzaffarabad , Azad J & K , Pakistan | 68,000 m ( 42.3 mi ) | 2017 | Part of the 969 MW Neelum Jhelum Hydropower Plant | Wastewater | Tunel Emisor Oriente | Mexico City , Mexico | 62,500 m ( 38.8 mi ) | 2008-2014 | Water management in Greater Mexico City . Longest wastewater tunnel

Example questions:
How long is the River Arpa - Lake Sevan tunnel that is situated at an altitude of 1,900 m ? | What is the length of the Delaware Aqueduct which was built between 1939 and 1945 ? | What is the length of the second longest tunnel in the world , the Päijänne Water Tunnel ? | What is the length of the Mass Rapid Transit ( Singapore ) , Downtown Line ?

Answers:
48,314 m ( 30.0 mi ) | 137,000 m ( 85.1 mi ) | 120,000 m ( 74.6 mi ) | 43,700 m ( 27.2 mi )