The Sonnenberg Tunnel is a long

motorway A controlled-access highway is a type of highway that has been designed for high-speed vehicular traffic, with all traffic flow—ingress and egress—regulated. Common English terms are freeway, motorway and expressway. Other similar terms i ...

tunnel A tunnel is an underground passageway, dug through surrounding soil, earth or rock, and enclosed except for the entrance and exit, commonly at each end. A pipeline is not a tunnel, though some recent tunnels have used immersed tube cons ...

, constructed between 1971 and 1976 and located in Lucerne, Switzerland. At its completion it was also the world's largest civilian

nuclear Nuclear may refer to: Physics Relating to the nucleus of the atom: * Nuclear engineering *Nuclear physics *Nuclear power *Nuclear reactor *Nuclear weapon *Nuclear medicine *Radiation therapy *Nuclear warfare Mathematics *Nuclear space *Nuclear ...

fallout shelter A fallout shelter is an enclosed space specially designated 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. During ...

, designed to protect 20,000

civilian Civilians under international humanitarian law are "persons who are not members of the armed forces" and they are not " combatants if they carry arms openly and respect the laws and customs of war". It is slightly different from a non-combatant ...

s in the eventuality of war or disaster. Catherine Frammery
"Dans les entrailles du Sonnenberg, monstrueux témoin de la Guerre froide"
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Le temps ''Le Temps'' ( literally "The Time") is a Swiss French-language daily newspaper published in Berliner format in Geneva by Le Temps SA. It is the sole nationwide French-language non-specialised daily newspaper of Switzerland. Since 2021, it has ...

'', Monday 15 August 2016 (page visited on 15 August 2015).

Motorway tunnel

The A2 motorway from

Chiasso Chiasso (; lmo, Ciass ) is a municipality in the district of Mendrisio in the canton of Ticino in Switzerland. As the southernmost of Switzerland's municipalities, Chiasso is on the border with Italy, in front of Ponte Chiasso (a frazione of Co ...

Basel , french: link=no, Bâlois(e), it, Basilese , neighboring_municipalities= Allschwil (BL), Hégenheim (FR-68), Binningen (BL), Birsfelden (BL), Bottmingen (BL), Huningue (FR-68), Münchenstein (BL), Muttenz (BL), Reinach (BL), Riehen (BS ...

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 story cavern between the tunnels contained shelter infrastructure including a command post, an emergency hospital, a radio studio, a telephone centre, prison cells and ventilation machines. The shelter was designed to withstand the blast from a 1

megaton Megaton may refer to: * A million tons * Megaton TNT equivalent, explosive energy equal to 4.184 petajoules * megatonne, a million tonnes, SI unit of mass Other uses * Olivier Megaton (born 1965), French film director, writer and editor * ''Me ...

explosion 1 kilometre away. The blast doors at the tunnel portals are 1.5 meters thick and weigh 350 tons. 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 2006, after a long political debate, it was decided to abandon the road tunnel's secondary civil defense function and instead convert the central seven story cavern into a shelter with a more modest capacity of 2,000. Since 2008 people can visit the cavern on guided tours and to get an insight into the bunker world of the Cold War.

References

Sources
Swiss still braced for nuclear warWorld's largest civilian tunnel to close
(

Institution of Civil Engineers The Institution of Civil Engineers (ICE) is an independent professional association for civil engineers and a charitable body in the United Kingdom. Based in London, ICE has over 92,000 members, of whom three-quarters are located in the UK, whi ...

25 September 2006).

External links

* {{coord, 47.038653, 8.294287, type:landmark_region:CH-LU_source:dewiki, name=Sonnenberg Tunnel south portal, display=title Tunnels completed in 1976 Road tunnels in Switzerland Buildings and structures in the canton of Lucerne Antinuclear shelters in Switzerland