Sonnenberg Tunnel
Encyclopedia
The Sonnenberg Tunnel is a 1,550m long motorway tunnel
, constructed between 1971 and 1976 and located near Lucerne
, Switzerland
. At its completion it was also the world's largest civilian nuclear
fallout shelter
, designed to protect 20,000 civilian
s in the eventuality of war or disaster.
from Chiasso
to Basel
passes through the tunnel and carries around 55,000 vehicles a day. There are tentative plans to construct a bypass to replace the section of the motorway that leads through Lucerne, which includes the Sonnenberg and Reussport tunnels.
nuclear
explosion 1 kilometre away. The blast doors at the tunnel portals are 1.5 metres thick and weigh 350 tonnes.
The logistical problems of maintaining a population of 20,000 in close confines were not thoroughly explored, and testing the installation was difficult because it required closing the motorway and rerouting the usual traffic. The only large-scale test, a five-day exercise in 1987 to practice converting the road tunnels into usable shelters, revealed many problems: Among other things it took 24 hours to fully close all four blast doors, and it proved impossible to set up the 20,000 beds within reasonable time. Afterwards the shelter's capacity was reassessed at 10,000-17,000. Doubts about the tunnel's viability as a shelter remained.
After the end of the Cold War
the high maintenance costs seemed unjustified for an installation that was clearly geared towards use during wartime and couldn't be readied within hours for short-term use after disasters. In 2005, after a long political debate, it was decided to abandon the road tunnel's secondary Civil Defense function and instead convert the central seven storey cavern into a shelter with a more modest capacity of 2,000.
Tunnel
A tunnel is an underground passageway, completely enclosed except for openings for egress, commonly at each end.A tunnel may be for foot or vehicular road traffic, for rail traffic, or for a canal. Some tunnels are aqueducts to supply water for consumption or for hydroelectric stations or are sewers...
, constructed between 1971 and 1976 and located near Lucerne
Lucerne
Lucerne is a city in north-central Switzerland, in the German-speaking portion of that country. Lucerne is the capital of the Canton of Lucerne and the capital of the district of the same name. With a population of about 76,200 people, Lucerne is the most populous city in Central Switzerland, and...
, Switzerland
Switzerland
Switzerland name of one of the Swiss cantons. ; ; ; or ), in its full name the Swiss Confederation , is a federal republic consisting of 26 cantons, with Bern as the seat of the federal authorities. The country is situated in Western Europe,Or Central Europe depending on the definition....
. At its completion it was also the world's largest civilian nuclear
Nuclear warfare
Nuclear warfare, or atomic warfare, is a military conflict or political strategy in which nuclear weaponry is detonated on an opponent. Compared to conventional warfare, nuclear warfare can be vastly more destructive in range and extent of damage...
fallout shelter
Fallout shelter
A fallout shelter is an enclosed space specially designed to protect occupants from radioactive debris or fallout resulting from a nuclear explosion. Many such shelters were constructed as civil defense measures during the Cold War....
, designed to protect 20,000 civilian
Civilian
A civilian under international humanitarian law is a person who is not a member of his or her country's armed forces or other militia. Civilians are distinct from combatants. They are afforded a degree of legal protection from the effects of war and military occupation...
s in the eventuality of war or disaster.
Motorway tunnel
The A2 motorwayA2 (Switzerland)
The A2 is a motorway in Switzerland. It forms Switzerland's main north-south axis from Basel to Chiasso, meandering with a slight drift toward the east....
from Chiasso
Chiasso
Chiasso is a municipality in the district of Mendrisio in the canton of Ticino in Switzerland.As the southernmost of Switzerland's municipalities, Chiasso is located at the border with Italy, in front of Ponte Chiasso...
to Basel
Basel
Basel or Basle In the national languages of Switzerland the city is also known as Bâle , Basilea and Basilea is Switzerland's third most populous city with about 166,000 inhabitants. Located where the Swiss, French and German borders meet, Basel also has suburbs in France and Germany...
passes through the tunnel and carries around 55,000 vehicles a day. There are tentative plans to construct a bypass to replace the section of the motorway that leads through Lucerne, which includes the Sonnenberg and Reussport tunnels.
Civil defense shelter
Based on a federal law from 1963, Switzerland aims to provide nuclear fallout shelters for the entire population of the country. The construction of a new tunnel near an urban centre was seen as an opportunity to provide shelter space for a large number of people at the same time. The installations that allowed the tunnel to be converted into a fallout shelter cost around $32.5 million, of which approximately $5 million were borne by the municipality of Lucerne. The shelter consisted of the two motorway tunnels (one per direction of travel), each capable of holding 10,000 people in 64 person subdivisions. A seven storey cavern between the tunnels contained shelter infrastructure including a command post, an emergency hospital, and a radio studio. The shelter was designed to withstand the blast from a 1 megatonTNT equivalent
TNT equivalent is a method of quantifying the energy released in explosions. The ton of TNT is a unit of energy equal to 4.184 gigajoules, which is approximately the amount of energy released in the detonation of one ton of TNT...
nuclear
Nuclear weapon
A nuclear weapon is an explosive device that derives its destructive force from nuclear reactions, either fission or a combination of fission and fusion. Both reactions release vast quantities of energy from relatively small amounts of matter. The first fission bomb test released the same amount...
explosion 1 kilometre away. The blast doors at the tunnel portals are 1.5 metres thick and weigh 350 tonnes.
The logistical problems of maintaining a population of 20,000 in close confines were not thoroughly explored, and testing the installation was difficult because it required closing the motorway and rerouting the usual traffic. The only large-scale test, a five-day exercise in 1987 to practice converting the road tunnels into usable shelters, revealed many problems: Among other things it took 24 hours to fully close all four blast doors, and it proved impossible to set up the 20,000 beds within reasonable time. Afterwards the shelter's capacity was reassessed at 10,000-17,000. Doubts about the tunnel's viability as a shelter remained.
After the end of the Cold War
Cold War
The Cold War was the continuing state from roughly 1946 to 1991 of political conflict, military tension, proxy wars, and economic competition between the Communist World—primarily the Soviet Union and its satellite states and allies—and the powers of the Western world, primarily the United States...
the high maintenance costs seemed unjustified for an installation that was clearly geared towards use during wartime and couldn't be readied within hours for short-term use after disasters. In 2005, after a long political debate, it was decided to abandon the road tunnel's secondary Civil Defense function and instead convert the central seven storey cavern into a shelter with a more modest capacity of 2,000.