Delaware Aqueduct (1945)
Delaware Aqueduct was constructed in 1945 to supply water from Rondout Reservoir to Hillview_Reservoir in New York City. Its 137,000 m length makes it world’s longest tunnel. Sixty four year old tunnel is facing huge leakage problem. Up to 20 to 35 million gallons water leak out every single day out of total 1.3 billion gallons.
Päijänne Water Tunnel (1982)
Päijänne Water Tunnel is 2nd largest tunnel in the world.Starting from Lake Päijänne (end in Greater Helsinki) to provide drinking water to southern cities of Finland. It took 10 years to complete 120,000 m long tunnel with an estimated cost of 200 million Euros.
Orange–Fish River Tunnel (1975)
Eastern Cape Provence was facing shortage of irrigational water because of that thousand of hector of soil couldn’t grow crops. Due to orange-fish river tunnel, irrigation of land is possible with the help of canals and damns. It is largest tunnel of Africa and 3rd largest in the world with estimated costs of about R30 000 /m length.
Bolmen Water Tunnel (1987)
Forth largest tunnel was completed in 12 years. People of Scania Provence (historically it was connected to Denmark) were facing water shortage, to fulfill the problem Bolmen tunnel was constructed in 1987.
Seikan Tunnel (1988)
Seikan Tunnel took 17 years to complete; started in 1971 and opened in 1988. Connecting largest island of Honshū with Hokkaidō Island (2nd largest island). It took 17 years to complete this project on estimated cost of US$3.6 billion