Tunnel facts for kids
A tunnel is an underground passage. Some tunnels are used for cars, and others are used for trains. Sometimes, a tunnel is used for movement of ships. Some tunnels are built for communication cables and some are built for electricity cables. Other tunnels are built for animals.
Tunnels are dug in different kinds of grounds, from soft sand to hard rock. The way of digging is chosen by the type of ground. There are two additional ways of digging : quarry and 'cut and cover'. In quarry, the tunnel path is drilled in a horizontal way. This system requires a deep tunnel that's built in a firm rock. In the 'cut and cover' system, a tunnel is dug in the ground and, afterwards, a roof is built above the tunnel. This system fits tunnels that are close to the ground like road tunnels and infrastructure.
Building tunnels is a large civil engineering project that could cost very high sums of money. The planning and building of a long tunnel may take many years.
The Channel Tunnel between France and England is one of the longest tunnels in the world. It is 50 kilometers long. The longest tunnel in the world, the Gotthard Base Tunnel, is being dug in Switzerland.
Reasons to build a tunnel
- A subway is based on a network of tunnels that are dug underground so the trains will not disturb and will not be disturbed by the local transport.
- On the path of a railroad track or a road a tunnel is dug when the lane encounters an obstacle such as a mountain to avoid bypassing the obstacle.
- A tunnel is built sometimes to overcome a water obstacle as a replacement for building a bridge above it.
- A tunnel is built to connect between military posts so the movement between them will not be visible for the enemy.
- A tunnel is built for infrastructure like electricity cables, water, communication and sewerage to avoid damage and disruption above ground.
- Some tunnels are used by prisoners to escape jail.
- Sometimes tunnels are used by criminals to do a bank robbery (e.g. in Brazil, Summer 2005).
Images for kids
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Tunnel in Fort de Mutzig, France
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Utility tunnel for heating pipes between Rigshospitalet and Amagerværket in Copenhagen, Denmark
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Joralemon Street Tunnel on 1913 postcard, part of the New York City Subway system
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The Harbor Tunnel in Baltimore, which carries I-895, serves as an example of a water-crossing tunnel built instead of a bridge.
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Cut-and-cover construction of the Paris Métro in France
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A workman is dwarfed by the tunnel boring machine used to excavate the Gotthard Base Tunnel (Switzerland), the world's longest railway tunnel.
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1886 illustration showing the ventilation and drainage system of the Mersey railway tunnel
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Illowra Battery utility tunnel, Port Kembla. One of many bunkers south of Sydney.
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Shark tunnel at the Georgia Aquarium
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A utility tunnel in Prague
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The upper-level traffic lanes through Yerba Buena Island, part of the San Francisco–Oakland Bay Bridge
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The 1,659-foot (506 m) Donner Pass Summit Tunnel (#6) was in service from 1868 to 1993.
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Liverpool Lime Street Approach. The original two track tunnel was removed to create a deep cutting. Some of the road bridges seen across the cutting are solid rock and in effect are a series of short tunnels.
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Small operational brick tunnel in France
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The Gotthard Base Tunnel is the first flat route through a major mountain range.
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The Big Dig road vehicle tunnel in Boston, USA
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The eastern portal of the abandoned Sideling Hill Tunnel, Pennsylvania, USA in 2009
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Tunnel formerly used for coal mining in New Taipei, Taiwan
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View through a natural tunnel in South Korea
See also
In Spanish: Túnel para niños
