A tunnel is an underground passage way. The definition of what constitutes a tunnel is not universally agreed upon. However, in general tunnels are at least twice as long as they are wide. In addition, they should be completely enclosed on all sides, save for the openings at each end. Some civic planners define a tunnel as 0. 1 miles (0. 16 kilometers) in length or longer, while anything shorter than this should be called a chute. For example, the underpass beneath Yahata Station in Kitakyushu, Japan is only 0. The Kagoshima Main Line (鹿児島本線 is a major part of the JR Kyūshū rail network and runs between Mojikō in Kitakyūshū, and Kagoshima Station is a city located in Fukuoka prefecture, Kyūshū, Japan. It is midway between Tokyo and Shanghai. For a topic outline on this subject see List of basic Japan topics. 08 miles long and therefore should not be considered a tunnel.

A tunnel may be for pedestrians or cyclists, for general road traffic, for motor vehicles only, for rail traffic, or for a canal. A pedestrian is a person travelling on foot whether Walking or Running. Cycling is the use of Bicycles or - less commonly - Unicycles Tricycles Quadricycles and other similar wheeled Human powered vehicles Traffic on Roads may consist of Pedestrians ridden or herded Animals Vehicles Streetcars and other Conveyances either singly A motor Vehicle is a Machine which incorporates a motor (sometimes known as an Engine) and which is used for Transportation "Railroad" and "Railway" both redirect here For other uses see Railroad (disambiguation. Canals are artificial channels for water There are two types of canals water conveyance canals which are used for the conveyance and delivery of water and Waterways Some are aqueducts, constructed purely for carrying water — for consumption, for hydroelectric purposes or as sewers — while others carry other services such as telecommunications cables. An aqueduct is an artificial channel that is constructed to convey water from one location to another Water supply is the process of self-provision or provision by third parties of water of various qualities to different users Hydroelectricity is electricity generated by Hydropower, ie the production of power through use of the gravitational force of falling water There are even tunnels designed as wildlife crossings for European badgers and other endangered species. Roads and Habitat Fragmentation Habitat fragmentation occurs when human-made barriers such as roads railroads canals power lines and oil pipelines penetrate and An endangered species is a population of an organism which is at risk of becoming Extinct because it is either few in numbers or threatened by changing environmental or predation Some secret tunnels have also been made as a method of entrance or escape from an area, such as the Cu Chi Tunnels or the tunnels connecting the Gaza Strip to Egypt. A secret passage (or hidden passage or a secret tunnel) is a hidden route that is used to travel stealthily The tunnels of Củ Chi are an immense network of connecting underground tunnels located in the Cu Chi district of Ho Chi Minh City, Vietnam, and are part Smuggling tunnels are secret tunnels, usually hidden underground used for Smuggling of Goods and people. The Gaza Strip (قطاع غزة, רצועת עזה Retzu'at 'Azza) is a coastal strip of land along the Mediterranean Sea, bordering Egypt on the south-west This article is about the country of Egypt For a topic outline on this subject see List of basic Egypt topics. Some tunnels are not for transport at all but are fortifications, for example Mittelwerk and Cheyenne Mountain. Central Works (German Mittelwerk) was the underground WWII rocket and aircraft factory in Germany that was operated by the government Central Works Ltd. Cheyenne Mountain is a mountain located on the southwest side of Colorado Springs Colorado, USA, and is home to the Cheyenne Mountain Air Force Station

The longest canal tunnel is the Standedge Tunnel in the United Kingdom, over three miles (5 km) long. The Standedge Tunnels (Standedge is normally pronounced Stannige) are four parallel Tunnels that run beneath the Pennines at the traditional

In the United Kingdom a pedestrian tunnel or other underpass beneath a road is called a subway. The United Kingdom of Great Britain and Northern Ireland, commonly known as the United Kingdom, the UK or Britain,is a Sovereign state located In the United Kingdom and some Commonwealth countries (such as India, Australia, Canada, Hong Kong, and Singapore) the term This term was used in the past in the United States, but now refers to underground rapid transit systems. The United States of America —commonly referred to as the A rapid transit, underground, subway, elevated railway or metro(politan system is an electric passenger railway

The central part of a rapid transit network is usually built in tunnels. To allow non-level crossings, some lines run in deeper tunnels than others. Rail stations with much traffic usually provide pedestrian tunnels from one platform to another, though others use bridges. A railway platform is a section of pathway alongside Rail tracks at a Train station, Metro station or Tram stop, at which passengers may board

Contents 1 Geotechnical investigation 2 Construction 2.1 Cut-and-cover 2.2 Boring machines 2.3 NATM 2.4 Pipe jacking 2.5 Underwater tunnels 2.6 Other 2.7 Choice of tunnels vs. bridges 3 Variant tunnel types 3.1 Double-deck tunnel 3.2 Short tunnels 3.3 Artificial tunnels 4 Examples of tunnels 4.1 In history 4.2 Longest 4.3 Notable 4.4 Other uses 5 Natural tunnel 6 Accidents 7 See also 8 References 9 External links

Geotechnical investigation

Main article: Geotechnical investigation

It is essential that any tunnel project starts with a comprehensive investigation of ground conditions. Geotechnical investigations are performed by geotechnical engineers or engineering geologists to obtain information on the physical properties of soil and rock around a site to design The results of the investigation will allow proper choice of machinery and methods for excavation and ground support, and will reduce the risk of encountering unforeseen ground conditions. In the early stages, the horizontal and vertical alignment will be optimised to make use of the best ground and water conditions.

In some cases, conventional desk and site studies will not produce sufficient information to assess, for example, the blocky nature of rocks, the exact location of fault zones, or stand-up times of softer ground. This may be a particular concern in large diameter tunnels. To overcome these problems, a pilot tunnel, or drift, may be driven ahead of the main drive. This smaller diameter tunnel will be easier to support when unexpected conditions occur, and will be incorporated in the final tunnel. Alternatively, horizontal boreholes may sometimes be used ahead of the advancing tunnel face.

Construction

Tunnels are dug in various types of materials, from soft clay to hard rock, and the method of excavation depends on the ground conditions. The Gotthard Base Tunnel (GBT is a Railway Tunnel under construction in Switzerland.

Cut-and-cover

Cut-and-cover is a simple method of construction for shallow tunnels where a trench is excavated and roofed over. A trench is a type of excavation or depression in the ground Trenches are generally defined by being deeper than they are wide (as opposed to a wider Gully or Ditch Vietnam roofjpg|thumb|The roofs of Vietnam.]] A roof is the covering on the uppermost part of a Building. A strong overhead support system is required to carry the load of the covering material.

Two basic forms of cut-and-cover tunnelling are available:

• Bottom-up method: A trench is excavated, with ground support as necessary, and the tunnel is constructed within. The tunnel may be of in situ concrete, precast concrete, precast arches, corrugated steel arches and such, with brickwork used in early days. The trench is then backfilled, with precautions regarding balancing compaction of the backfill material, and the surface is reinstated.
• Top-down method: In this method, side support walls and capping beams are constructed from ground level, using slurry walling, contiguous bored piles, or some other method. A shallow excavation is then made to allow the tunnel roof to be constructed using precast beams or in situ concrete. The surface is then reinstated except for access openings. This allows early reinstatement of roadways, services and other surface features. Excavation machinery is then lowered into the access openings, and the main excavation is carried out under the permanent tunnel roof, followed by constructing the base slab.

Shallow tunnels are often of the cut-and-cover type (if under water, of the immersed-tube type), while deep tunnels are excavated, often using a tunnelling shield. A tunnelling shield is a protective structure used in the excavation of tunnels through soil that is too soft or fluid to remain stable during the time it takes to line the tunnel For intermediate levels, both methods are possible.

Large cut-and-cover boxes are often used for underground metro stations, such as Canary Wharf tube station in London. Canary Wharf tube station is a London Underground station on the Jubilee Line, between Canada Water and North Greenwich. This construction form generally has two levels, which allows economical arrangements for ticket hall, station platforms, passenger access and emergency egress, ventilation and smoke control, staff rooms, and equipment rooms. The interior of Canary Wharf station has been likened to an underground cathedral due to the sheer size of the excavation. This contrasts with most traditional stations on London Underground, where bored tunnels were used for stations and passenger access. The London Underground is a Metro system serving a large part of Greater London and neighbouring areas of Essex, Hertfordshire and Buckinghamshire

Boring machines

Main article: Tunnel boring machine

Tunnel boring machines (TBMs) and associated back-up systems can be used to highly automate the entire tunneling process. A tunnel boring machine ( TBM) is a machine used to excavate Tunnels with a circular cross section through a variety of soil and rock strata. Nevada ( is a state located in the western region of the United States of America. There are a variety of TBMs that can operate in a variety of conditions, from hard rock to soft water-bearing ground. Some types of TBMs, bentonite slurry and earth-pressure balance machines, have pressurised compartments at the front end, allowing them to be used in difficult conditions below the water table. The water table is the level at which the ground water pressure is equal to Atmospheric pressure. This pressurizes the ground ahead of the TBM cutter head to balance the water pressure. The operators work in normal air pressure behind the pressurised compartment, but may occasionally have to enter that compartment to renew or repair the cutters. This requires special precautions, such as local ground treatment or halting the TBM at a position free from water. Despite these difficulties, TBMs are now preferred to the older method of tunneling in compressed air, with an air lock/decompression chamber some way back from the TBM, which required operators to work in high pressure and go through decompression procedures at the end of their shifts, much like divers.

Until recently the largest TBM built was used to bore the Green Heart Tunnel (Dutch: Tunnel Groene Hart) as part of the HSL-Zuid in the Netherlands. HSL-Zuid ( Hogesnelheidslijn Zuid, Southern High-Speed Line is a 125-km long high-speed railway line under construction between the Netherlands and It had a diameter of 14. 87 m. [1]

Nowadays even larger machines exist: two for the M30 ringroad in Madrid, Spain, and two for the Chong Ming tunnels in Shanghai, China. These machines are 15,2 m and 15,4 m in diameter respectively. The two machines for Spain were built by Mitsubishi/Duro Felguera and Herrenknecht. Herrenknecht AG is a German manufacturer of Tunnel boring machines of all sizes The TBMs for China were built by Herrenknecht.

NATM

The New Austrian Tunneling Method (NATM) was developed in the 1960s. The New Austrian Tunneling method (NATM was developed between 1957 and 1965 in Austria. The main idea of this method is to use the geological stress of the surrounding rock mass to stabilize the tunnel itself. Stress is a measure of the average amount of Force exerted per unit Area. In Geology, rock is a naturally occurring aggregate of Minerals and/or Mineraloids The Earth's outer solid layer the ‘ Lithosphere Mass is a fundamental concept in Physics, roughly corresponding to the Intuitive idea of how much Matter there is in an object Based on geotechnical measurements, an optimal cross section is computed. Geotechnical engineering is the branch of Civil engineering concerned with the engineering behavior of earth materials In Geometry, a cross section is the intersection of a body in 2-dimensional space with a line or of a body in 3-dimensional space with a plane etc The excavation is immediately protected by thin shotcrete, just behind the excavation. Shotcrete and gunite are two commonly used terms for substances applied via Pressure hoses Shotcrete is mortar or (usually Concrete conveyed This creates a natural load-bearing ring, which minimizes the rock's deformation. In Materials science, deformation is a change in the shape or size of an object due to an applied force.

By special monitoring the NATM method is very flexible, even at surprising changes of the geomechanical rock consistency during the tunneling work. Condition monitoring is the process of monitoring a parameter of condition in machinery such that a significant change is indicative of a developing failure Geomechanics ( Greek prefix geo meaning Earth; and Mechanics) is the study of the behavior of Soil and rock. The measured rock properties lead to appropriate tools for tunnel strengthening. A broader definition of a tool is an entity used to interface between two or more domains that facilitates more effective action of one domain upon the other In Materials science, the strength of a material refers to the material's ability to resist an applied force In the last decades also soft ground excavations up to 10 km became usual.

Pipe jacking

Pipe Jacking, also known as pipejacking or pipe-jacking, is a method of tunnel construction where hydraulic jacks are used to push specially made pipes through the ground behind a tunnel boring machine or shield. This technique is commonly used to create tunnels under existing structures, such as roads or railways.

Underwater tunnels

There are also several approaches to underwater tunnels, for instance an immersed tube as in the Sydney Harbour, and the Posey and Webster Street Tubes which connect the cities of Oakland and Alameda, California, running beneath the Alameda-Oakland Estuary. An Immersed Tube is a kind of underwater Tunnel comprised of segments and/or elements constructed elsewhere and floated to the tunnel’s site to be sunken into place The Sydney Harbour Tunnel is a twin tube road tunnel in Sydney, Australia. The Posey Tube and the Webster Street Tube are two parallel underwater tunnels connecting the cities of Oakland and Alameda California, running beneath Oakland (ˈoʊklənd founded in 1852 is the eighth-largest city in the U Alameda is a city in Alameda County, California, United States. The Oakland Estuary is the body of water separating the cities of Oakland and Alameda, California, in the San Francisco Bay Area.

Other

Other tunneling methods include:

• Drilling and blasting
• Slurry-shield machine
• Wall-cover construction method. Before the advent of Tunnel boring machines drilling and blasting was the only economical way of excavating long Tunnels through hard rock where digging is not A shield is a protective device meant to intercept attacks The term often refers to a device that is held in the hand as opposed to Armour or a Bullet proof vest

Choice of tunnels vs. bridges

For water crossings, a tunnel is generally more costly to construct than a bridge. Navigational considerations may limit the use of high bridges or drawbridge spans intersecting with shipping channels, necessitating a tunnel. A drawbridge is a type of Movable bridge typically associated with the entrance of a Castle. Bridges usually require a larger footprint on each shore than tunnels. In areas with expensive real estate, such as Manhattan and urban Hong Kong, this is a strong factor in tunnels' favor. Manhattan Island, in New York Harbor, is much the largest part of the Borough of Manhattan, one of the Five Boroughs which form the City of New York Hong Kong ( officially the Hong Kong Special Administrative Region, is a territory located on China 's south coast on the Pearl River Delta, and borders Boston's Big Dig project replaced elevated roadways with a tunnel system to increase traffic capacity, hide traffic, reclaim land, redecorate, and reunite the city with the waterfront. The Big Dig is the unofficial name of the Central Artery/Tunnel Project ( CA/T) a Megaproject that rerouted the Examples of water-crossing tunnels built instead of bridges include the Holland Tunnel and Lincoln Tunnel between New Jersey and Manhattan in New York City, and the Elizabeth River tunnels between Norfolk and Portsmouth, Virginia and the Westerschelde tunnel, Zeeland, Netherlands. The Holland Tunnel is a highway Tunnel under the Hudson River connecting the island of Manhattan in New York City with Jersey The Lincoln Tunnel is a 15 mile (24 km long Tunnel under the Hudson River, connecting Weehawken, New Jersey and the borough New Jersey ( is a state in the Mid-Atlantic and Northeastern regions of the United States. The City of New York The Elizabeth River is a short Tidal estuary forming an arm of Hampton Roads at the southern end of Chesapeake Bay in southeast Virginia in the Norfolk is an Independent city in the Commonwealth of Virginia in the United States Portsmouth is an Independent city located in the US Commonwealth of Virginia. Western Scheldt (Dutch Westerschelde) in the province Zeeland in the southwestern Netherlands, is the Estuary of the Scheldt river Other reasons for choosing a tunnel instead of a bridge include avoiding difficulties with tides, weather and shipping during construction (as in the 51. 5 km Channel Tunnel), aesthetic reasons (preserving the above-ground view, landscape, and scenery), and also for weight capacity reasons (it may be more feasible to build a tunnel than a sufficiently strong bridge). The Channel Tunnel (Le tunnel sous la Manche also known as the Chunnel, is a undersea rail tunnel linking Folkestone, Kent in England with

Some water crossings are a mixture of bridges and tunnels, such as the Denmark to Sweden link and the Chesapeake Bay Bridge-Tunnel in the eastern United States. The Oresund Bridge ( Danish Øresundsbroen, Swedish Öresundsbron, joint hybrid name Øresundsbron) is a combined two-track rail The Chesapeake Bay Bridge-Tunnel (CBBT is a 23-mile (37-km long facility that connects the Delmarva Peninsula with southeastern Virginia in the United States The United States of America —commonly referred to as the

Variant tunnel types

Double-deck tunnel

Some tunnels are double-deck, for example the Eastern Harbour Crossing in Hong Kong, where roads and rails (the MTR metro) occupy different decks of the tunnel. The Eastern Harbour Crossing ( abbreviated as "EHC" (東隧 is a tunnel in Hong Kong. Hong Kong ( officially the Hong Kong Special Administrative Region, is a territory located on China 's south coast on the Pearl River Delta, and borders MTR, or Mass Transit Railway, is the Rapid transit Railway system in Hong Kong.

The two major segments of the San Francisco-Oakland Bay Bridge (completed in 1936) are linked by a double-deck tunnel, once the largest diameter tunnel in the world. At construction this was a combination bidirectional rail and truck pathway on the lower deck with automobiles above, now converted to one-way road vehicle traffic on each deck.

A recent double-decke tunnel with both decks for motor vehicles is the Fuxing Road Tunnel in Shanghai, China. Shanghai ( 上[[wikt 海|海]] is the largest city in China in terms of population and one of the largest urban areas in the world with over 20 million Cars travel on the two-lane upper deck and heavier vehicles on the single-lane lower.

Short tunnels

Artificial tunnels

Overbridges can sometimes be built by covering a road or river or railway with brick or still arches, and then levelling the surface with earth. In railway parlance, a surface-level track which has been built or covered over is normally called a covered way.

Snow sheds are a kind of artificial tunnel built to protect a railway from avalanches of snow. A snow shed or avalanche shed is a Structure that provides Avalanche protection for Roads and railroad tracks. Similarly the Stanwell Park, New South Wales steel tunnel, on the South Coast railway line, protects the line from rockfalls. Stanwell Park is a picturesque coastal village and northern suburb of Wollongong, New South Wales, Australia. The South Coast Line is in the intercity region of Sydney 's CityRail services

Common utility ducts are man-made tunnels created to carry two or more utility lines underground. A common utility duct, sometimes called a common utility conduit is any structure - above on or below ground - that carries more than two types of Public utility lines Through co-location of different utilities in one tunnel, organizations are able to reduce the costs of building and maintaining utilities.

Examples of tunnels

In history

• World's oldest underwater tunnel is rumored to be the Terelek kaya tüneli under Kızıl River, a little south of the towns of Boyabat and Duragan in Turkey. Boyabat is a town and district of Sinop Province in the Black Sea region of Turkey. Turkey (Türkiye known officially as the Republic of Turkey ( is a Eurasian Country that stretches Estimated to have been built more than 2000 years ago (possibly 5000) it is assumed to have had a defense purpose.
• The qanat or kareez of Persia is a water management system used to provide a reliable supply of water to human settlements or for irrigation in hot, arid and semi-arid climates. A qanat (from قناة) or kareez (from كاريز) is a Water management system used to provide a reliable supply of water to human settlements A qanat (from قناة) or kareez (from كاريز) is a Water management system used to provide a reliable supply of water to human settlements The Persian Empire was a series of Iranian empires that ruled over the Iranian plateau, the original Persian homeland and beyond in Western Asia The oldest and largest known qanat is in the Iranian city of Gonabad which after 2700 years still provides drinking and agricultural water to nearly 40,000 people. Its main well depth is more than 360 meters and its length is 45 kilometers.

• The Eupalinian aqueduct on the island of Samos (North Aegean, Greece). The Tunnel of Eupalinos or Eupalinian aqueduct (in Greek gr ''Efpalinion orygma'' Ευπαλίνιον όρυγμα is a tunnel of 1036 m length in Samos, Samos (Σάμος is a Greek island in the North Aegean Sea, south of Chios, north of Patmos and the Dodecanese, and off The Thames Tunnel is an underwater tunnel built beneath the River Thames in London. London ( ˈlʌndən is the capital and largest urban area in the United Kingdom. The Tunnel of Eupalinos or Eupalinian aqueduct (in Greek gr ''Efpalinion orygma'' Ευπαλίνιον όρυγμα is a tunnel of 1036 m length in Samos, Samos (Σάμος is a Greek island in the North Aegean Sea, south of Chios, north of Patmos and the Dodecanese, and off North Aegean is one of the thirteen Peripheries of Greece. It consists of the prefectures of Chios, Lesbos and Samos. Greece (Ελλάδα transliterated: Elláda, historically, Ellás,) officially the Hellenic Republic (Ελληνική Δημοκρατία Built in 520 BC by the ancient Greek engineer Eupalinos of Megara. Eupalinos (or Eupalinus) of Megara, was an Ancient Greek Engineer who built the Tunnel of Eupalinos on Samos Island Megara ( Greek:, "Big Houses" is an ancient city (pop Eupalinos organised the work so that the tunnel was begun from both sides of mount Kastro. The two teams advanced simultaneously and met in the middle with excellent accuracy, something that was extremely difficult in that time. The aqueduct was of utmost defensive importance, since it ran underground and it was not easily found by an enemy who could otherwise cut off the water supply to Pythagoreion, the ancient capital of Samos. The remains of the Pythagoreion an ancient fortified port with Greek and Roman monuments and a spectacular tunnel the Tunnel of Eupalinos or Eupalinian aqueduct along Samos (Σάμος is a Greek island in the North Aegean Sea, south of Chios, north of Patmos and the Dodecanese, and off The tunnel's existence was recorded by Herodotus (as was the mole and harbour, and the third wonder of the island, the great temple to Hera, thought by many to be the largest in the Greek world). The precise location of the tunnel was only re-established in the 19th century by German archaeologists. The tunnel proper is 1030 metres (3,430 ft) long and visitors can still enter it Eupalinos tunnel.
• Sapperton Canal Tunnel on the Thames and Severn Canal in England, dug through hills, which opened in 1789, was 3. The Sapperton Canal Tunnel is a Tunnel on the Thames and Severn Canal near Cirencester in Gloucestershire, England. The Thames and Severn Canal is a former Canal in Gloucestershire in the south of England, though there are plans to restore it England is a Country which is part of the United Kingdom. Its inhabitants account for more than 83% of the total UK population whilst its mainland 5 km long and allowed boat transport of coal and other goods. Above it runs the Sapperton Long Tunnel which carries the "Golden Valley" railway line between Swindon and Gloucester. Swindon ( is a large town in the ceremonial county of Wiltshire in the South West of England, midway between Bristol (64 km / 40 miles Gloucester (ˈɡlɒstɚ) is a city, district and County town of Gloucestershire in the South West region of England.
• The tunnel created for the first true steam locomotive, the Penydarren locomotive, was built prior to Richard Trevithick was able to make his historic journey from Penydarren to Abercynon in 1804. Penydarren was the fourth of the great Ironworks established at Merthyr Tydfil in South Wales. Richard Trevithick ( April 13, 1771 &ndash April 22, 1833) was a British Penydarren was the fourth of the great Ironworks established at Merthyr Tydfil in South Wales. Abercynon is a community and a small Village in the Cynon Valley, in Rhondda Cynon Taff, Wales. Part of this tunnel can still be seen at Pentrebach, Merthyr Tydfil. Pentrebach (sometimes written Pentre-Bach ( translation small village) is a village in the County Borough of Merthyr Tydfil, Wales. Merthyr Tydfil today Government The current Borough boundaries date back to 1974 when the former county borough of Merthyr Tydfil expanded slightly to cover This is arguably the oldest railway tunnel in the world, for self-propelled steam engines on rails.
• The Montgomery Bell Tunnel in Tennessee, a 290 water diversion tunnel built by slave labor in 1819, was the first "full-scale" tunnel in the United States. The Montgomery Bell Tunnel, also known as the ' Patterson Forge Tunnel, in Cheatham County Tennessee, is a long tunnel through Limestone rock which was
• Box Tunnel in England, which opened in 1841, was the longest railway tunnel in the world at the time of construction. Box Tunnel is a railway Tunnel in western England, between Bath and Chippenham, dug through the Box Hill. It was dug and has a length of 2. 9 km.
• The Thames Tunnel, built by Marc Isambard Brunel and his son Isambard Kingdom Brunel and opened in 1843, was the first underwater tunnel and the first to use a tunnelling shield. The Thames Tunnel is an underwater tunnel built beneath the River Thames in London. Sir Marc Isambard Brunel, FRS ( 25 April 1769 &ndash 12 December 1849) was a French -born engineer who settled in the Isambard Kingdom Brunel, FRS (9 April 1806 &ndash 15 September 1859 (ˈɪzəmbɑrd ˈkɪŋdəm brʊˈnɛl was a British Engineer. A tunnelling shield is a protective structure used in the excavation of tunnels through soil that is too soft or fluid to remain stable during the time it takes to line the tunnel Originally used as a foot-tunnel, it is now part of the East London Line of the London Underground. The East London Line was a line of the London Underground, coloured orange on the Tube map. The London Underground is a Metro system serving a large part of Greater London and neighbouring areas of Essex, Hertfordshire and Buckinghamshire
• James Greathead, in constructing the City & South London Railway tunnel beneath the Thames, in the late 1880's, brought together three key elements of tunnel construction under water: 1) shield method of excavation; 2) permanent cast iron tunnel lining; 3) construction in a compressed air environment to inhibit water flowing through soft ground material into the tunnel heading. James Henry Greathead ( 6 August 1844 - 21 October[[ 896]] was an Engineer renowned for his work on the London Underground railway ^[1]
• St. Clair Tunnel, opened in 1890, linked those elements on a much larger scale and was the first full-size subaqueous tunnel in North America^[1]
• The Cobble Hill Tunnel and Murray Hill Tunnel in New York City are the world's oldest railway tunnels lying below streets, roofed over in 1850 and the 1850s, respectively. The St Clair Tunnel is the name for two separate rail tunnels which were built under the St The Cobble Hill Tunnel (popularly the Atlantic Avenue Tunnel) of the Long Island Rail Road is an abandoned railroad tunnel beneath Atlantic Avenue in downtown The City of New York
• The oldest sections of the London Underground were built using the cut-and-cover method in the 1860s. The London Underground is a Metro system serving a large part of Greater London and neighbouring areas of Essex, Hertfordshire and Buckinghamshire The Metropolitan, Hammersmith & City, Circle and District lines were the first to prove the success of a metro or subway system. A rapid transit, underground, subway, elevated railway or metro(politan system is an electric passenger railway
• St. Clair Tunnel, opened in 1890, was the first full-size subaqueous tunnel in North America
• Col de Tende Road Tunnel, one of the first longer road tunnels under a pass, runs between France and Italy. The St Clair Tunnel is the name for two separate rail tunnels which were built under the St Col de Tende Road Tunnel is a 3182 metre long road tunnel running under Col de Tende between France and Italy At its opening it may have been one of world's longest road tunnels.
• The Holland Tunnel was the first underwater tunnel designed for automobiles, which required a novel ventilation system. The Holland Tunnel is a highway Tunnel under the Hudson River connecting the island of Manhattan in New York City with Jersey The Holland Tunnel is a highway Tunnel under the Hudson River connecting the island of Manhattan in New York City with Jersey

See also the History of Rapid transit. A rapid transit, underground, subway, elevated railway or metro(politan system is an electric passenger railway A rapid transit, underground, subway, elevated railway or metro(politan system is an electric passenger railway

Longest

Main article: List of tunnels by length

• The Seikan Tunnel in Japan is the longest rail tunnel in the world at 53. The world's longest tunnels - in use The world's longest tunnels - under construction Possibly incomplete table The Seikan Tunnel (青函トンネル Seikan Tonneru or 青函隧道 Seikan Zuidō) is a 53 For a topic outline on this subject see List of basic Japan topics. 9 km (33. 4 miles), of which 23. 3 km (14. 5 miles) is under the sea.
• The Channel Tunnel between France and the United Kingdom under the English Channel is the second-longest, with a total length of 50 km (31 miles), of which 39 km (24 miles) is under the sea. The Channel Tunnel (Le tunnel sous la Manche also known as the Chunnel, is a undersea rail tunnel linking Folkestone, Kent in England with This article is about the country For a topic outline on this subject see List of basic France topics. The United Kingdom of Great Britain and Northern Ireland, commonly known as the United Kingdom, the UK or Britain,is a Sovereign state located
• The Lötschberg Base Tunnel opened in June 2007 in Switzerland is the longest land tunnel, with a total of 34. The Lötschberg Base Tunnel (LBT is a 34577 km (215 mile long new railway Tunnel on the Bern-Lötschberg-Simplon railway cutting through the Switzerland (English pronunciation; Schweiz Swiss German: Schwyz or Schwiiz Suisse Svizzera Svizra officially the Swiss Confederation 5 km (21. 5 miles).
• The Lærdal Tunnel in Norway from Lærdal to Aurland is the world's longest road tunnel, intended for cars and similar vehicles, at 24. Lærdal is a municipality in the southwestern part of Sogn og Fjordane county, Norway. Aurland is a municipality in the county of Sogn og Fjordane, Norway. 5 km (15. 2 miles).
• The Zhongnanshan Tunnel in People's Republic of China opened in January 2007 is the world's longest highway tunnel and the longest road tunnel in Asia, at 18. Zhongnanshan Tunnel, or Qinling Zhongnanshan Tunnel (Chinese 秦岭终南山公路隧道) is the longest two-tube road Tunnel in the world Talk People's Republic of China) PEOPLE'S REPUBLIC OF CHINA ARTICLE GUIDELINES * * * * * * * * * * * * * * * * * * * * * * Before adding any more images to this * * page please do carefully consider * * whether they would be mere decoration * * or actually improve 0 km (11. 3 miles).
• Päijänne-tunneli is the world's longest complete tunnel that is bored into rock. The Päijänne Water Tunnel ( Päijännetunneli) is the world's longest continuous rock Tunnel located in the Southern Finland It is located in southern Finland and it is 120 km long. Finland, officially the Republic of Finland ( is a Nordic country situated in the Fennoscandian region of northern Europe. Its purpose is to provide the Greater Helsinki metropolitan area with fresh water. Greater Helsinki (Suur-Helsinki Swedish: Storhelsingfors) Capital Region ( Pääkaupunkiseutu, Huvudstadsregionen) Helsinki

Notable

• The Lincoln Tunnel between New Jersey and New York is one of the busiest vehicular tunnels in the world, at 120,000 vehicles/day. The Lincoln Tunnel is a 15 mile (24 km long Tunnel under the Hudson River, connecting Weehawken, New Jersey and the borough New Jersey ( is a state in the Mid-Atlantic and Northeastern regions of the United States. New York ( is a state in the Mid-Atlantic and Northeastern regions of the United States and is the nation's third most populous
• The Fredhälls Tunnel in Stockholm, Sweden
• Williamson's tunnels in Liverpool, built by a wealthy eccentric are probably the largest underground folly in the world. Essingeleden is a Freeway that goes from Solna to Stockholm, Sweden, crossing the westmost parts of central Stockholm by going over Kungsholmen ('stɔkhɔlm is Sweden 's Capital and its largest City. It is the site of the national Swedish government, the parliament, and the "Sverige" redirects here For other uses see Sweden (disambiguation and Sverige (disambiguation. Liverpool ( is a City and Metropolitan borough of Merseyside, England along the eastern side of the Mersey Estuary
• New York City Water Tunnel No. 3[2], started in 1970, has an expected completion date of 2020. New York City Water Tunnel No 3 is the largest capital construction project in New York City 's history and among the most complex engineering projects in the world today
• The Chicago Deep Tunnel Project is a network of 109 miles (197 km) of tunnels designed to reduce flooding in the Chicago area. The Tunnel and Reservoir Plan (abbreviated TARP and more commonly known as the Deep Tunnel Project or the Chicago Deep Tunnel) is a large Civil The Chicago metropolitan area is the Metropolitan area associated with the city of Chicago in the United States and its suburbs Started in the mid 1970s, the project is due to be completed in 2019.
• Moffat Tunnel in Colorado straddles the Continental Divide. The Moffat Tunnel is a railroad/ water tunnel that cuts through the Continental Divide in north-central Colorado. The State of Colorado ( or chiefly by nonresidents) is a state located in the Rocky Mountain region of the United States of America. A continental divide is a line of elevated Terrain which forms a border between two watersheds such that Water falling on one side of the line eventually The tunnel is 6. 2 mi (10. 0 km) long and at 9,239 feet (2,816 m) above sea level is the highest railroad tunnel in the United States. The United States of America —commonly referred to as the
• The Fenghuoshan tunnel on Qinghai-Tibet railway is the world's highest railway tunnel. The Fenghuoshan railway tunnel in the is the highest railway tunnel in the world The Qingzang railway, Qinghai–Xizang railway, or Qinghai–Tibet railway ( mtsho bod lcags lam མཚོ་བོད་ལྕགས་ལམ། is a high-altitude
• The Houston Downtown Tunnel System is a system of tunnels about twenty feet below Houston's downtown street system. The Houston tunnel system is a system of tunnels 6 m (about 20 ft below Houston 's downtown street system The system forms a network of subterranean, climate-controlled, pedestrian walkways that link twenty-five full city blocks.
• The Sydney Harbour Tunnel in Sydney, Australia was built in 1992 to augment the Sydney Harbour Bridge. The Sydney Harbour Tunnel is a twin tube road tunnel in Sydney, Australia. Sydney (ˈsɪdniː is the most populous city in Australia, with a Metropolitan area population of approximately 4 For a topic outline on this subject see List of basic Australia topics. } The Sydney Harbour Bridge is a Steel arch bridge across Sydney Harbour that carries rail vehicular and pedestrian traffic between the Sydney central business

Other uses

Excavation techniques, as well as the construction of underground bunkers and other habitable areas, are often associated with military use during armed conflict, or civilian responses to threat of attack. Tunnel warfare is a type of Warfare that occurs in Tunnels It can be sometimes linked with Urban warfare, as tunnels are often found in urban area and

The use of tunnels for mining is called drift mining. Drift mining is a method of accessing valuable geological material such as Coal, by cutting into the side of the earth rather than tunneling straight downwards (see Shaft

Natural tunnel

• Natural Tunnel State Park (Virginia) features an 850 foot (255 meter) natural tunnel, really a limestone cave, that has been used as a railroad tunnel since 1890.
• Punarjani Guha

Snow tunnels are created by voles, chipmunks and other rodents for protection and access to food sources. Punarjani Guha is a natural tunnel 150 meters long in the rocky cliff Larger versions are created by humans, usually for fun.

For more information regarding tunnels built by animals, see Burrow

Accidents

• Balvano train disaster

See also

• List of tunnels
• Undersea tunnel
• Underground city
• Urban exploration
• Roof and tunnel hacking
• Smuggling tunnel
• List of rathole tunnels
• Wind tunnel
• World's longest tunnels
• Lava tube
• Vinh Moc tunnels

References

External links

• Trans Global Highway and proposed tunnels.
• Royal Engineers Museum British Army First World War Tunnelling.
• Directory of the world's longest tunnels by category
• ITA-AITES International Tunnelling Association
• Tunnels & Tunnelling International magazine

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