Two of the more interesting tunnels that humans build are transportation tunnels for trains and cars and water aqueducts supplying large cities.
The largest existing aqueduct in the world is the Thirlmere Aqueduct in North West England built between 1890 and 1925 and running 96 miles over and through hill and dale of the English countryside in pipes, streams, tunnels dams and aqueducts.
The United States has the second largest “water tunnel” with a storage capacity of 550 billion gallons and providing 1.2 billion gallons of fresh water per day to the New York City’s 8 million residents; 95% of the aqueduct’s water is moved by gravity. The “Big Apple” water system has three aqueducts and three tunnels. The aqueducts serve as reservoirs and the tunnels serve as the distribution system.
New York City Reservoirs & Aqueducts
- New Croton Aqueduct – completed in 1890 brings water from New Croton reservoir in Westchester and Putnam counties and supplies about 10% of New York City’s water needs.
- Catskill Aqueduct – completed in 1960 brings water from two reservoirs in the Eastern Catskill Mountains and supplies about 40% of New York City’s water needs
- The Delaware Aqueduct – completed in 1945 brings water from tributaries of the Delaware River in the Western Catskills and provides about 50% of the New York City’s water supply.
New York City Tunnels & Distribution System
- New York City water tunnel number one-completed in 1917 runs from Hillview reservoir under the central Bronx, Harlem River, Westside, Midtown and lower East side and under the East River to Brooklyn where it connects to tunnel number 2.
- New York City water tunnel number 2 – completed in 1935 runs from Hillview reservoir under the central Bronx, East River and Western Queens to Brooklyn where it connects to tunnel number one and the Richmond tunnel to Staten Island.
- New York City water tunnel number three, the largest New York City construction project in history has a distribution system including an extensive grid of water mains 6,500 miles long.