Wind tunnels play a large role in the safety of our aircraft. Engineers use wind tunnels to create different types of wind flow and other environmental conditions in order to see how the models stand up to the tests. From these tests, they can then determine the effect of the forces on larger commercial aircraft and are then in a position to modify and improve the aircraft to make it as safe as possible for flight under inclement weather.
Mine tunnels are created in order to extract precious minerals and metal deposits deep below the surface of the earth. When mining for coal, miners first have to dig a tunnel close to where the coal is located. These tunnels can be vertical, horizontal or sloping depending on where the coal is located and where several passageways are connected to the tunnels. For ease in the removal of metals and to ensure the safety of the miners, roof supports and other equipment are needed to keep the tunnels open.
Water, sewage and gas lines run through tunnels located under the ground. Cities and towns funnel water from rain, snow and other surface water through its tunnel drain systems to local streams, rivers and eventually to our lakes and oceans. Gas lines travel hundreds of miles through tunnels, providing power to villages, towns and cities, and sewage collected from tunnels are treated to kill disease-causing mechanisms and can be used for non-potable purposes such as landscape irrigation.
Underwater tunnels enable trains, cars and trucks to cross rivers easing the traffic on above-ground routes. The Holland Tunnel, completed in 1927 is one of the world's greatest engineering projects. About 100,000 vehicles use the tunnel to travel between New York City and New Jersey per day. The Chunnel, the latest in underwater tunnels, connects England to France and is 32 miles long, 23 of which is 150 feet under the seabed of the English Channel. Travel across the Chunnel can be done by high-speed trains.
Subway transportation is an alternative to driving a car in a large city. The tunnels for the subways can run either underground or above ground, and some tracks within the tunnel run alongside each other and resemble an open trench with wide-sloping sides. Subways tunnels can cover great distances around a city, snaking in several directions and significantly reducing the congestion of vehicular and pedestrian traffic on the streets.
