A tunnel is an underground passage. When designed for use by traffic, it may be called an underpass. The definition of what constitutes a tunnel is not universally agreed upon. However, in general tunnels have a ratio of the length of the passage to the width of at least 2 to 1. In addition, they should be completely enclosed on all sides (save the openings) for the length of the covered area. A tunnel may be for pedestrians and/or cyclists, for general road traffic, for motor vehicles only, for rail traffic, or for a ca ...

Including:

• Tunnel - Types of tunnels
• Tunnel - Construction
• Tunnel - Choice of tunnels vs. bridges
• Tunnel - Very short tunnels
• Tunnel - Artificial Tunnels
• Tunnel - Examples of tunnels
• Tunnel - In history
• Tunnel - The longest
• Tunnel - Notable
• Tunnel - Other uses

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See also:

Tunnel, Tunnel - Types of tunnels, Tunnel - Construction, Tunnel - Choice of tunnels vs. bridges, Tunnel - Very short tunnels, Tunnel - Artificial Tunnels, Tunnel - Examples of tunnels, Tunnel - In history, Tunnel - The longest, Tunnel - Notable, Tunnel - Other uses

Read more here: » Tunnel: Encyclopedia II - Tunnel - Very short tunnels

Tunnels are dug in various types of materials, from soft clays to hard rocks, and the method of excavation depends on the type of soil. When digging soft clays the New Austrian Tunneling method might be applied. When digging in weak rocks a tunnel boring machine (TBM) is often used. In hard rocks, blasting may be deemed most suitable, as in the Norwegian tunneling method. Various combinations of these methods and many others are also possible. There are also several approaches to underwater tunnels, for inst ...

See also:

Tunnel, Tunnel - Types of tunnels, Tunnel - Construction, Tunnel - Choice of tunnels vs. bridges, Tunnel - Very short tunnels, Tunnel - Artificial Tunnels, Tunnel - Examples of tunnels, Tunnel - In history, Tunnel - The longest, Tunnel - Notable, Tunnel - Other uses

Read more here: » Tunnel: Encyclopedia II - Tunnel - Types of tunnels

Tunnel - In history. Eupalinos Tunnel on the island Samos (Greece). Built 520 BC by the greek engineer Eupalinos. Eupalinos organised the work so that the tunnel was begun from both sides of the hill and the two teams met in the middle. The estimates for the time required range from 5 to 15 years: the mountain is solid limestone and one has to suppose that many of the slaves doing the work died. The tunnel's existence was recorded by Herodotus (as was the mole and harbour, and the third wonder of the island ...

See also:

Tunnel, Tunnel - Types of tunnels, Tunnel - Construction, Tunnel - Choice of tunnels vs. bridges, Tunnel - Very short tunnels, Tunnel - Artificial Tunnels, Tunnel - Examples of tunnels, Tunnel - In history, Tunnel - The longest, Tunnel - Notable, Tunnel - Other uses

Read more here: » Tunnel: Encyclopedia II - Tunnel - Examples of tunnels

World's longest tunnels - Railroad excluding subways. World's longest tunnels - Vehicular. Tunnel, List of tunnels World's longest tunnels - Top 100. ^  A subaqueous tunnel ^  Under construction Including:

• World's longest tunnels - The World's Longest Tunnels
• World's longest tunnels - Railroad excluding subways
• World's longest tunnels - Vehicular
• World's longest tunnels - Top 100

Read more here: » World's longest tunnels: Encyclopedia - World's longest tunnels

The Williamson Tunnels in Edge Hill, (Liverpool) are a collection of apparently pointless tunnels built by local men employed by Joseph Williamson from the early 1800's to 1840. Williamson's tunnels - The Tunnels. The tunnels are in an area to the east of the Liverpool Metropolitan Cathedral in a rectangle bordered by Mason Street, Grinfield Street, Smithdown Lane and Paddington. They run beneath the brow of the 'Edge Hill', which is one of the highest points in Liverpool. The reason for their creati ...

Including:

• Williamson's tunnels - The Tunnels
• Williamson's tunnels - Joseph Williamson
• Williamson's tunnels - The Tourist Attraction
• Williamson's tunnels - Timeline

Read more here: » Williamson's tunnels: Encyclopedia - Williamson's tunnels

Box Tunnel is a railway tunnel in western England, between Bath and Chippenham, dug through the Box Hill. It was built for the original route of the Great Western Railway under the direction of the GWR's engineer Isambard Kingdom Brunel. The tunnel is 2939m (1mi 1452yd) in length, straight, and descends a 1 in 100 gradient from the east. Construction started in 1836, and the tunnel opened in 1841. The lives of about 100 navvies (railway construction workers) were lost during construction. At the time of opening it was the longe ...

Including:

• Box Tunnel - Brunel's Birthday
• Box Tunnel - A Secret Tunnel?

Read more here: » Box Tunnel: Encyclopedia - Box Tunnel

The Channel Tunnel, (French: le tunnel sous la Manche; popularly nicknamed the Chunnel in English, although this has been largely abandoned in favour of the Tunnel) is a 50-km-long (~31 imperial miles) rail tunnel beneath the English Channel at the Straits of Dover, connecting Cheriton in Kent, the United Kingdom, and Coquelles near Calais in northern France. A long-standing and hugely expensive project that saw several false starts, it was finally completed in 1994. It is the second-longest rail tunnel in ...

Including:

• Channel Tunnel - Historical attempts or proposals for a tunnel
• Channel Tunnel - Second tunnel
• Channel Tunnel - The current tunnel
• Channel Tunnel - Planning
• Channel Tunnel - Construction
• Channel Tunnel - Completion
• Channel Tunnel - Statistics
• Channel Tunnel - Operation
• Channel Tunnel - Fire
• Channel Tunnel - Sovereignty
• Channel Tunnel - Asylum seekers
• Channel Tunnel - Financial trouble
• Channel Tunnel - Appearances in film

Read more here: » Channel Tunnel: Encyclopedia - Channel Tunnel

The Chicago Tunnel Company built a unique freight tunnel network under the downtown of the city of Chicago. It inspired the construction of the London Post Office Railway. Chicago Tunnel Company - History. Construction of the subway began in 1899, and the full system with a tunnel under almost every street of downtown Chicago was finished in 1906. Six feet wide by seven and a half high (1.8 by 2.3 metres) tunnels were officially constructed to house only telephone cables, but the Illinois Tunnel Company als ...

Including:

• Chicago Tunnel Company - History
• Chicago Tunnel Company - Experiment
• Chicago Tunnel Company - Operation
• Chicago Tunnel Company - Closure
• Chicago Tunnel Company - Disaster
• Chicago Tunnel Company - For further reading

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In the wrist there is a sheath of tough connective tissue which envelopes and protects one nerve (median nerve) and tendons, which attach your muscles to the wrist and hand bones. The carpal tunnel is the space between this sheath (above) and the bones (below) making up the wrist and hand (carpal bones). The term 'carpal tunnel' is also used quite commonly to refer to 'carpal tunnel syndrome' which is a condition where the median nerve is pinched within the tunnel and causes pa ...

Including:

• Carpal tunnel - Basic description
• Carpal tunnel - Medical/Anatomical definition
• Carpal tunnel - Boundaries
• Carpal tunnel - Contents
• Carpal tunnel - Relevance

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A wind tunnel is a research tool developed to assist with studying the effects of air moving over or around solid objects. Air is blown or sucked through a duct equipped with a viewing port anod instrumentation where models or geometrical shapes are mounted for study. Various techniques are then used to study the actual airflow around the geometry and compare it with theoretical results, which must also take into account the Reynolds n ...

Including:

• Wind tunnel - History
• Wind tunnel - Windtunnel classification
• Wind tunnel - Well known wind tunnels around the world

Read more here: » Wind tunnel: Encyclopedia - Wind tunnel

Carpal tunnel syndrome is a medical condition in which the median nerve is compressed at the wrist causing symptoms like tingling, pain, coldness, and sometimes weakness in parts of the hand. It is the best known of a class of disorders called repetitive strain injuries. Carpal tunnel syndrome - Anatomy. The median nerve runs through the carpal tunnel, a canal in the wrist that is surrounded by bone on three sides, and a fibrous sheath (the flexor retinaculum) on the other. In addition to the nerve, many of ...

Including:

• Carpal tunnel syndrome - Anatomy
• Carpal tunnel syndrome - Incidence
• Carpal tunnel syndrome - Symptoms
• Carpal tunnel syndrome - Causes
• Carpal tunnel syndrome - Diagnosis
• Carpal tunnel syndrome - Treatment and Prevention
• Carpal tunnel syndrome - Immobilizing braces
• Carpal tunnel syndrome - Localized Steroid Injections
• Carpal tunnel syndrome - Soft Tissue Therapy
• Carpal tunnel syndrome - Prioritizing Hand Activities and Ergonomics
• Carpal tunnel syndrome - Carpal Tunnel Relief Surgery
• Carpal tunnel syndrome - Long term recovery

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The Atlantic Avenue Tunnel (or Cobble Hill Tunnel of the Long Island Rail Road) is an abandoned railroad tunnel beneath Atlantic Avenue in downtown Brooklyn, New York. When open, it ran for about 2750 feet (830 m) between Hicks Street and Boerum Place. It was opened on December 3, 1844 and was finished by January 1, 1845, as an open cut--that is, a reinforced trench open to the sky. It was built to reduce the grade of the railroad line on its way to the South Ferry at the foot of Atlantic Street (now Avenue), fro ...

Read more here: » Cobble Hill Tunnel: Encyclopedia - Cobble Hill Tunnel

Bridges and tunnels in New York City - East River. From north to south: Throgs Neck Bridge Bronx-Whitestone Bridge Rikers Island Bridge (only connects Rikers Island to Queens) Hell Gate Bridge Triborough Bridge Roosevelt Island Bridge (east channel only) Queensboro Bridge Williamsburg Bridge Manhattan Bridge Including:

• Bridges and tunnels in New York City - Bridges by water body
• Bridges and tunnels in New York City - East River
• Bridges and tunnels in New York City - Hudson River
• Bridges and tunnels in New York City - New York Bay
• Bridges and tunnels in New York City - Newtown Creek
• Bridges and tunnels in New York City - Harlem River
• Bridges and tunnels in New York City - Other
• Bridges and tunnels in New York City - Tunnels by water body
• Bridges and tunnels in New York City - East River
• Bridges and tunnels in New York City - Hudson River
• Bridges and tunnels in New York City - Other bridges and tunnels
• Bridges and tunnels in New York City - Bridges by use
• Bridges and tunnels in New York City - Sources

Read more here: » Bridges and tunnels in New York City: Encyclopedia - Bridges and tunnels in New York City

The tunnels are in an area to the east of the Liverpool Metropolitan Cathedral in a rectangle bordered by Mason Street, Grinfield Street, Smithdown Lane and Paddington. They run beneath the brow of the 'Edge Hill', which is one of the highest points in Liverpool. The reason for their creation is unknown. The most common presumption is that they were constructed to provide employment during the economic recession following the Napoleonic Wars. If this is true then the tunnels may be the oldest known job creation scheme. Other less wide ...

See also:

Williamson's tunnels, Williamson's tunnels - The Tunnels, Williamson's tunnels - Joseph Williamson, Williamson's tunnels - The Tourist Attraction, Williamson's tunnels - Timeline

Read more here: » Williamson's tunnels: Encyclopedia II - Williamson's tunnels - The Tunnels

Shanghai tunnels have been used to smuggle people out of the United States to work as slaves aboard ships. The long land borders of the United States have always attracted drug smugglers, and countless tunnels have been built. Due to the country's restrictive policy on immigration in the wake of the September 11, 2001 attacks, and heightened security, many more secret tunnels were built to enter the country from Mexico, most running between Tijuana on the Mexican side and San Diego, California on the American side. The prevalent use is drug smuggling, but many other operati ...

See also:

Smuggling tunnels, Smuggling tunnels - Smuggling tunnel in Sarajevo Bosnia, Smuggling tunnels - Smuggling tunnels in Rafah Gaza Strip, Smuggling tunnels - The American smuggling tunnels, Smuggling tunnels - The Underground Railroad

Read more here: » Smuggling tunnels: Encyclopedia II - Smuggling tunnels - The American smuggling tunnels

Urban tunneling has the special challenge of requiring that the ground surface be undisturbed. This means that ground subsidence must be avoided. The normal method of doing this is to maintain the soil pressures during and after the tunnel construction. There is some difficulty in doing this, particularly in varied geologies (imagine tunnel boring through a region where the upper portion of the tunnel face is wet sand and the lower portion is hard rock). TBMs with positive face control are used in such situations. There are thr ...

See also:

Tunnel boring machine, Tunnel boring machine - Description, Tunnel boring machine - Shields, Tunnel boring machine - Urban tunneling and near surface tunneling

Read more here: » Tunnel boring machine: Encyclopedia II - Tunnel boring machine - Urban tunneling and near surface tunneling

World's longest tunnels - Railroad excluding subways. World's longest tunnels - Vehicular. ...

See also:

World's longest tunnels, World's longest tunnels - The World's Longest Tunnels, World's longest tunnels - Railroad excluding subways, World's longest tunnels - Vehicular, World's longest tunnels - Top 100

Read more here: » World's longest tunnels: Encyclopedia II - World's longest tunnels - The World's Longest Tunnels

Channel Tunnel - Planning. In 1957 le Tunnel sous la Manche Study Group was formed. It reported in 1960 and recommended two main railway tunnels and a smaller service tunnel. The project was launched in 1973 but folded due to financial problems in 1975 after the construction of a 250 metre test tunnel. In 1984 the idea was relaunched with a joint British and French government request for proposals to build a privately-funded link. Of the four submissions received, the one most closely resembling the 1973 p ...

See also:

Channel Tunnel, Channel Tunnel - Historical attempts or proposals for a tunnel, Channel Tunnel - Second tunnel, Channel Tunnel - The current tunnel, Channel Tunnel - Planning, Channel Tunnel - Construction, Channel Tunnel - Completion, Channel Tunnel - Statistics, Channel Tunnel - Operation, Channel Tunnel - Fire, Channel Tunnel - Sovereignty, Channel Tunnel - Asylum seekers, Channel Tunnel - Financial trouble, Channel Tunnel - Appearances in film

Read more here: » Channel Tunnel: Encyclopedia II - Channel Tunnel - The current tunnel

A tunnel boring machine (TBM) typically consists of one or two shields (large metal cylinders) and trailing support mechanisms. At the front end of the shield a rotating cutting wheel is located. Behind the cutting wheel there is a chamber where, depending on the type of the TBM, the excavated soil is either mixed with slurry (so-called slurry TBM) or left as-is. The choice for a certain type of TBM depends on the soil conditions. Systems for removal of the s ...

See also:

Tunnel boring machine, Tunnel boring machine - Description, Tunnel boring machine - Shields, Tunnel boring machine - Urban tunneling and near surface tunneling

Read more here: » Tunnel boring machine: Encyclopedia II - Tunnel boring machine - Description