A tunnel or tunnel structure is mostly an underground structure similar to a tube, which is used to pass under obstacles such as mountains , water or other traffic routes . Tunnels are rarely used for other purposes such as protecting residents from road or rail traffic noise . In this case they are often referred to as underground routes . Tunnels are among the engineering structures .
Definition according to DIN
In Germany , tunnels are built in accordance with the applicable DIN standard 1076 - engineering structures along roads and paths; Monitoring and testing defined as structures below the surface of the earth or water. Above-ground enclosures for traffic routes with a length of at least 80 m and gallery structures are also considered tunnels. According to the standard, underpasses do not count as tunnel structures if they were constructed using the cut-and-cover method and are shorter than 80 meters.
The term tunnel first appeared in English in the early 15th century and referred to a funnel-shaped bird net. It is not clear whether the term comes from French 'tonnelle': net or French 'ton': small barrel . Tunnel was first used for tubes in the 1540s and for the first time for underground passage in the 1660s . The term came back from English to French and replaced the word mine, which was previously used for underground structures .
In linguistic usage, the neuter is rarely used, but it is found in Switzerland. The final stress, which was typical up to the beginning of the 20th century, as in French, has largely given way to the stress on the first syllable, with the exception of some speakers in the south of the German-speaking area and especially in South Tyrol.
In addition to the length, tunnels u. a. the following characteristic dimensions are given:
- Cross-sectional area : The area of an area defined by the tunnel walls at right angles to the course of the tunnel.
- Excavated area : The area of an area defined by the mountain profile at right angles to the course of the tunnel.
- Covering : Distance between the top edge of the tunnel and the top edge of the terrain above.
- Clearance height: distance between the top edge and the floor of the tunnel. For structural reasons, tunnels are usually arched so that the maximum clear height is significantly greater than the clear passage height that can be used by the vehicles - the minimum permissible clear height in the area of the passage profile.
Ancient and early Middle Ages
The forerunners of the large tunnels serving traffic were underground irrigation and drainage tunnels that were built since ancient times. Since the beginning of the 1st millennium BC In the various states of the Orient, groundwater was developed through qanats , in which vertical shafts were driven into the depths along the line of the future tunnel and connected to one another. A qanat always had a slight incline towards a settlement. This enabled the groundwater to be tapped underground and led to the settlement through the qanat. Otherwise, the same groundwater would have had to be drawn up from a great depth below the settlement. The Canaanites were already digging a 70 meter long tunnel into the rock in Megiddo , which gave them covered access to an underground cistern outside the city walls.
The tunnel construction is different: Here the lines followed in the so-called counter-location procedure. In the process, search tunnels were first cut from the starting point and the end point of the tunnel , which were only expanded to the required cross-section after the meeting. In the early Bronze Age settlement of Khirbet ez-Zaraqon in Jordan, there is a 200-meter-long tunnel, at the ridge of which the search tunnels can still be clearly seen. Its dating to before the use of iron tools seems problematic. For example, the Greeks built on Samos for a covert water supply around 530 BC. The 1063 meter long tunnel of the Eupalinos . Under the Judean king Hezekiah , the 533 meter long Hezekiah tunnel was also dug to supply water during sieges from the Gihon source to the pond of Siloam in Jerusalem . About 150 BC The 700 meter long tunnel to Qumran on the Dead Sea was also used to supply water. The Etruscans created the less spectacular numerous cuniculi, narrow tunnels that were used for water pipes, drainage or water collection. In the 6th century BC They built the first road tunnels in the Alban Hills. The Romans in particular carried out many buildings, including the derivation of Lake Fucino , a 5623 meter long tunnel from the middle of the 1st century. Vespasian had a new tunnel built through the Intercisa pass (Furlo) on the Via Flaminia in 77 . An aqueduct tunnel in the Algerian Bejaia from the 2nd century AD is particularly well-known by the Roman builder Nonius Datus, who described the difficulties of the counter-location proceedings in an inscription. The Romans only built road tunnels in Italy: the architect L. Cocceius Auctus built road tunnels with Sextus Pompeius in 38/37 BC during the civil war . BC three tunnels around Cumae and on Lake Avern and two more between Naples and Puteoli , which were up to 1000 meters long. There is evidence of a road tunnel on the island of Ponza . Based on the remains of ancient shaft structures in the vicinity of Dover , modern research assumes that the Romans did not only deal theoretically with the idea of an English Channel tunnel . The Buco di Viso (French: Le Pertuis du Viso) in the Cottian Alps is considered the oldest traffic tunnel in the Alps . It was completed in 1480 and was used to transport goods with pack animals .
The oldest early medieval water tunnel in Central Europe is the pin arm of the Alm Canal in Salzburg , which served the city's utility water supply and was cut through the Mönchsberg in 1143 . Another tunnel, which presumably dates from this time, is the Fulbert tunnel on the Laacher See , which was built after 1164 and was used to lower the water level during floods.
Before the age of railway construction, there were only four tunnels north of the Alps in Germany. The zoo tunnel in Blankenheim in the Eifel is one of them . The introduction of gunpowder for rock blasting made tunnels possible for the construction of canals since the 17th century , for example the 157 meter long Malpas tunnel for the Canal du Midi (around 1680) and the shipping tunnel of Weilburg an der Lahn . In 1708, the Urnerloch near Andermatt, the first tunnel on an Alpine road (length 64 m) was built for goods and passenger traffic. The Sigmundstor in Salzburg, completed in 1765, with a length of 131 meters, is Austria's oldest road tunnel. The Sapperton Canal Tunnel, opened in 1789 on the Thames & Severn Canal in England, was 3.5 kilometers long and allowed the transport of coal freighters. The 2869 meter long Norwood Tunnel in England, opened in 1775, is another example. Through the 4880 meter long Mauvages tunnel in the Canal de la Marne au Rhin in Alsace, built from 1842 to 1847 , boats and ships were tugged with an electric chain tug that was put into operation in 1912 . However, the towing facility is no longer in operation, as the canal is mainly used by recreational boaters.
The first traffic tunnel under a river was built under the Thames in London between Rotherhithe and Wapping from 1825 to 1841 with an interruption of seven years. After being equipped with lights, lanes, stairs and a machine system for drainage, it was opened to public traffic on March 25, 1843. It was only used for pedestrians until 1865, after which this Thames Tunnel was used by the East London Railway as part of the London Underground (most recently East London Line ).
The first American traffic tunnel under a river opened in Chicago on January 1, 1869 . In 1899 the Spreetunnel Stralau was put into operation in Berlin. The Elbe Tunnel was opened in Hamburg on September 7, 1911 .
George Stephenson created the first railway tunnels on the Liverpool – Manchester route from 1826 to 1830. From 1837 to 1839, the first full-line tunnel was built on the European mainland on the Leipzig – Dresden route near Oberau . The invention of dynamite and rock drilling machines powered by compressed air made it possible to build large mountain tunnels.
The 3182-meter-long Col-de-Tende road tunnel that was driven under the Col de Tende in 1882 is remarkable . It was the first road tunnel under an alpine pass and at the time it was probably one of the longest tunnels in the world open to public traffic.
Tunnels also wrote political and military history: Towards the end of the Second World War , the German armaments industry relocated numerous production facilities in bomb-proof walled-in traffic tunnels as part of the so-called U relocation program . In the 1960s, secret escape tunnels from East Berlin and the GDR to West Berlin and spy tunnels vice versa were built during the time of the Berlin Wall . During the Vietnam War in the 1970s , the Viet Cong owned a large number of tunnels near the South Vietnamese capital Saigon , in which the soldiers of the Vietnamese People's Liberation Army hid during American air raids and patrols, maintained supply camps and operated and cared for the wounded. During the Bosnian War in the 1990s, the Bosnian troops built a secret tunnel from Sarajevo under the Serbian siege ring through which they received modest supplies.
Tunnels for traffic routes can be single , double or multi-lane. Tunnels can be operated in alternating directional traffic. This is the rule on motorways, two parallel tubes can then be viewed as one tunnel.
Railway tunnels are primarily used to bypass topographical obstacles . In contrast to road vehicles, adhesive sheets can only negotiate small gradients and negotiate large arcs , which is why the route often cannot be guided over or around obstacles.
In mountain railways , spiral tunnels are used, which serve to gain the height of the route by artificially lengthening the route through a tunnel in the mountains. Spiral tunnels occur in extreme topographical conditions such as cog railways .
Since road vehicles can negotiate greater gradients than rail vehicles, the construction of road tunnels on a larger scale only began with the construction of motorways and other expressways. Before, road tunnels were only found in the mountains and mostly only briefly.
More recently, tunnels have been built for reasons of landscape and environmental protection. For example, the Jagdberg Tunnel , which went into operation in 2014, was built on the 4 federal motorway west of Jena in Thuringia to free the ecologically valuable Leutratal from car traffic.
Furthermore, some green bridges are so long that they are considered tunnels.
This type of tunnel is mainly used in cities. There, pedestrian tunnels often serve as a replacement for pedestrian overpasses over wide streets or as a connection between underground stations. Passenger tunnels are created especially in train stations . In cities in colder climates there are larger networks of pedestrian tunnels called underground cities . Examples of pedestrian tunnels are the Berlin pedestrian tunnel or the egg tunnel in Bad Kleinen . The Schlossberg tunnel in Tübingen , on the other hand, was built in 1974 for pedestrians to cross this natural mountain range.
Criminals sometimes build temporary tunnels to break into a bank or to smuggle illegal drugs across national borders ; some prisoners build temporary tunnels to escape prison or prison camps. The escape tunnels in Berlin during the division of Germany were used to enable citizens of the Soviet occupation zone and later the GDR to “ escape from the republic ”, which was criminalized there .
In the Lamprechtshöhle in the state of Salzburg, a tunnel was blasted into the rock decades ago and later made lockable with an iron door in order to be able to bypass a siphon that temporarily blocks the dry path.
In cities, tunnels are sometimes created as pedestrian areas in order to create pleasant “outside” temperatures in front of business premises all year round, in the eastern Canadian city of Toronto as protection from the extreme cold in winter.
As the Channel Tunnel ( Canal tunnel ) Structures in which an be designated navigable channel passes under landscape surveys such as hills or mountains. When planning canals, heights that cannot be traversed with a cut in the terrain are avoided, whenever possible, with a longer stretch of the same height or crossed with rows of locks . Where neither is an option or where such a solution would require too much mass movement, the construction of a tunnel can be the economically optimal option.
Canal tunnels are mostly designed for single-lane traffic. Sufficient waiting rooms and signaling devices for traffic control are required in front of both portals . In some tunnels the waterway is accompanied by a shoulder above the water level, which was used for patrols and pulling boats. The first canal tunnel was built for the Canal du Midi in the 17th century.
Selection of long canal tunnels
- the 7,120 meter long tunnel du Rove of the Canal de Marseille au Rhône near Marseille (no longer navigable after partial collapse since 1963)
- the 5677 meter long Riquevaltunnel in Picardy, Canal de Saint-Quentin , France
- the 5,209 meter standedge tunnel in the Huddersfield Narrow Canal , England
- the 4880 meter long Mauvages tunnel of the Canal de la Marne au Rhin ( German: Rhine-Marne Canal ) in France
- the 4,354 meter long basement de Ruyaulcourt of the Canal du Nord , France
- the 3490 meter long, now collapsed Sapperton Canal Tunnel of the Thames-Severn Canal in England
- the 3333 meter long Voûte de Pouilly-en-Auxois summit tunnel of the Canal de Bourgogne ( German: Burgundy Canal ) in France
- the 2836 meter long Norwood Tunnel in the Chesterfield Canal , England
The only navigable tunnel in Germany is the 195 meter long Weilburger shipping tunnel on the Lahn, which was opened on September 18, 1847.
Apex tunnel and base tunnel
Tunnels that lead through mountains can be divided into apex tunnels , more rarely pass tunnels , and base tunnels .
Examples of pass routes with a crest tunnel:
- Road over the Col du Galibier : the road, built in 1890, crosses under the 2645 m high pass with a crest tunnel 363 m long, in which the road reaches a height of 2556 m.
- Tauern tunnel of the Tauern Railway through the main Alpine ridge , built 1901–1906, peak at 1226 m above sea level. A.
- Großglockner High Alpine Road : The road, built from 1930 to 1932, crosses under the 2576 m high Hochtor with a crest tunnel of 311 m length, the highest point of which is at 2504 m.
With base tunnel tunnels are called, which lead without ramps with little slope by a mountain range, but much longer and more complicated to manufacture than summit tunnel.
Examples of base tunnels in the Alps:
- Mont Blanc Tunnel : The 11.6 km long road tunnel was opened in 1965.
- Tauern tunnel : The 6.4 km long road tunnel on the Tauern A 10 motorway was opened in 1975.
- Arlberg Tunnel : The 13.9 km long road tunnel of the Arlberg expressway S 16 was opened in 1978.
- Gotthard Base Tunnel : The 57 km long railway tunnel was opened on June 1, 2016.
The apex and base tunnels can reach considerable lengths. In order to make the traffic routes as efficient as possible, solutions were usually chosen that were just feasible with the technology of the time or that reached the limits of the financing options. The long tunnels, which only have the gradient necessary for drainage, usually do not have good natural ventilation because the highest point of the tunnel is in the mountain. In the Furka Base Tunnel , for example, this led to fog formation, which corroded the rails so that they had to be replaced prematurely. In terms of safety, the long tunnels are a particular challenge, as they are often located in remote areas and the emergency services have long journeys in the event of incidents in the tunnel. In some tunnels, such as the Elbe Tunnel in Hamburg, there are special tunnel fire brigades. In 1999, severe tunnel fires occurred in the Mont Blanc and Tauern tunnels (motorway) , which resulted in measures to improve tunnel safety.
Underwater tunnels can be used to cross bodies of water. In general, underwater tunnels are more expensive than bridges, but they can cover greater distances. Bridges can often only be used to a limited extent on shipping routes because they hinder shipping.
Examples of tunnels that were built in place of bridges for shipping reasons:
- Old Elbe Tunnel (construction: 1907–1911, between St. Pauli and Steinwerder )
- Holland Tunnel (construction: 1920–1927, between New Jersey and Manhattan )
- Lincoln Tunnel (construction: 1934–1937, middle tube, between New Jersey and Manhattan , later expansion with 2 more tubes)
Underwater tunnel to the immersed tunnel will be built by prefabricated tunnel sections are floated and lowered; when they are on the bottom they are connected to each other, sealed and pumped dry.
Examples of tunnels built as submerged tunnels:
- 1961: Rendsburg Canal Tunnel
- 1975: New Elbtunnel Hamburg (first to third tube, counting from the east) part of the federal highway 7
The construction of a tunnel is costly and often a challenge to the engineering. Long tunnels are usually built from both sides using the opposite direction , especially in the mountains or under the sea . In the meantime there are structures in which intermediate attacks that were opened up with shafts, for example, were built (the Gotthard Base Tunnel, for example ). This shortens the construction time, since there are then 4 instead of only 2 drives.
The construction of tunnels is done in a closed or open construction method. With the closed construction method, the construction is carried out by mining in the New Austrian Construction Method using drilling and blasting or mechanically using a tunnel boring machine, i.e. in shield driving or open driving. When building a tunnel using the cut-and- cover method , the tunnel structure is constructed in an open excavation pit, which is then backfilled.
In the case of longer tunnels in the mountains and in the high mountains , often only the opposite site drive, possibly supplemented by further drives from intermediate attacks , is a possible construction method in order to reduce the construction time. The basis for a successful tunnel construction is a precise measurement of the tunnel to be built.
In a long tunnel (with a straight route), the line of the constant gradient deviates significantly from a straight line . Thanks to the curvature of the earth, this line lies approximately on a circle with the earth's radius . The deviation from the straight line is already 8 m over a length of 10 km. For structures around 1 km long or more, higher geodesy is therefore necessary in order to achieve sufficient accuracy. The surveying error discovered when the two 10 km long aligning tunnels of the Simplon Tunnel met was around 22 centimeters.
The construction of tunnels is very investment-intensive. In Germany, for example, a single-tube, two-lane road tunnel, which is mined in medium-heavy soil conditions, costs an average of 20,000 euros per meter. This is only an average value, which can deviate downwards, especially strongly upwards. In addition, for example, lighting, ventilation, fire water lines, industrial buildings are 15 to 20 percent for the equipment of the tunnel, etc. In addition to the enormous construction costs in part is entertainment of the tunnel also costly. An average of 180,000 euros per kilometer of tunnel section is calculated annually.
Ventilation is necessary to provide people with adequate visibility and breathable air when building a tunnel, e.g. As by a suspended ceiling in the tunnel Lutte or via a parallel tunnel and transverse shock or transverse supply or exhaust air tunnel. The ventilation during the construction period also serves in particular to remove the explosive gases during blasting and to remove the exhaust gases from the construction machinery used.
A functioning safety system in tunnels can save lives in the event of an accident or fire . The following structural and technical measures increase the safety in tunnels:
- Drainage system for flammable liquids,
- System for automatic fire detection (fire alarm),
- System for measuring visibility,
- System for wind speed measurement,
- Ventilation systems for operational and fire ventilation,
- Tunnel tubes separated according to the direction of travel (one-way traffic tunnel, "twin tube" in contrast to two-way traffic tunnels),
- Emergency exits to escape routes , mostly formed by cross passages (cross tunnels) to adjacent tunnel tubes,
- additional rescue tunnels, which can mainly be used as an escape route , but also as access for emergency services,
- Escape route notices with distance information and escape route lighting,
- Emergency lighting in railway tunnels,
- Emergency bays near road tunnels,
- Emergency niche with emergency call system and with fire alarm and fire extinguisher ,
- Sprinkler system and extinguishing water extraction nozzle for the fire brigade ,
- Video surveillance system ,
- Loudspeaker system for voice announcements by control room personnel and fire brigade, especially for evacuation requests in the event of fire and other safety instructions. Since 2009, almost only the synchronized longitudinal announcement speaker system (SLASS technology) recommended by the Federal Highway Research Institute (BAST) has been installed in Germany for road traffic tunnels with boundary horn loudspeakers, which for the first time provides an acceptable intelligibility of such announcements despite the extreme acoustic conditions is achieved.
In the case of tunnels, intensive safety management is necessary, which includes the creation of alarm plans and the implementation of exercises with the local fire brigades. Fire brigades in whose protected area there are tunnel structures for traffic routes are called portal fire brigades . They have special equipment for use in tunnels. Numerous serious accidents in tunnels show that many tunnels only have poor safety systems.
In order to increase the safety in road tunnels, tests are continuously carried out by the traffic clubs, in which around 30 tunnels across Europe are compared with one another. Public pressure is to be exerted on the tunnel operators by publishing the results. In 2005, the ÖAMTC started the EuroTAP (European Tunnel Assessment Program) safety project funded by the European Union , in which traffic clubs from ten other countries are participating. To improve tunnel safety in road tunnels, the European Union issued Directive 2004/54 / EC, the implementation of which in the member states had to be completed by April 30, 2016. In Austria, the Tunnel Safety Act, which came into force on May 1, 2006, was passed, which applies to all road tunnels on motorways and expressways with a length of 500 meters or more.
Despite all these measures, 100% safety cannot be guaranteed, especially in road tunnels. Users must also be aware of the dangers and follow the rules such as:
- Pay attention to the traffic lights
- Switch on the car radio with traffic information
- Never enter the tunnel behind a burning vehicle
- Reduce driving speed
- Switch on the vehicle lights
- Maintain a safe distance
- don't stop in the tunnel
- Pay attention to the adjustment of the lighting conditions of the eyes , remove sunglasses
- When leaving, expect strongly changed weather conditions such as ice, fog, blowing snow
- Find out what to do in the event of accidents and fires in tunnels
The longest tunnels on earth
The longest tunnels in the world that are already open to traffic are:
- Gotthard Base Tunnel , 57.1 kilometers, Switzerland, railroad
- Seikan Tunnel , 53.9 kilometers, Japan, Railroad
- Eurotunnel , 50.5 kilometers, France / Great Britain, railway
- Lötschberg base tunnel , 34.6 kilometers, Switzerland, railroad
- New Guanjiao Tunnel , 32.6 kilometers, China, railroad
- Guadarrama Tunnel , 28.4 kilometers, Spain, railroad
- Taihangshan Tunnel , 27.8 kilometers, China, Railroad
- Hakkoda Tunnel , 26.5 kilometers, Japan, Railroad
- Iwate Ichinohe Tunnel , 16 miles, Japan, Railroad
- Lærdals Tunnel , 24.5 kilometers, Norway, road
- List of the longest tunnels in Germany
- List of alpine tunnels
- List of tunnels in Germany
- List of tunnels in Austria
- List of Swiss tunnels
- Amphibious tunnel
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