Bunker
The doors must be at least as strong as the walls. The usual design is a trap-door, to minimize the size and expense. To reduce the weight, the door is normally constructed of steel, with a fitted steel lintel and frame. Very thick wood also serves, and is more resistant to fire because it chars rather than melts. If the door is on the surface and will be exposed to the blast wave, the edge of the door is normally counter-sunk in the frame so that the blast wave or a reflection cannot lift the edge. A bunker should have two doors. Door shafts may double as ventilation shafts to reduce digging.
In bunkers inhabited for prolonged periods, large amounts of ventilation or air conditioning must be provided in order to prevent ill effects of heat. In bunkers designed for war-time use, manually-operated ventilators must be provided because supplies of electricity or gas are unreliable. One of the most efficient manual ventilator designs is the Kearny Air Pump. Ventilation openings in a bunker must be protected by blast valves. A blast valve is closed by a shock wave, but otherwise remains open. One form of expedient blast valve is tire-treads nailed or bolted to frames strong enough to resist the maximum overpressure.
If a bunker is in a built-up area, it may have to include water-cooling or an immersion tub and breathing tubes to protect inhabitants from fire storms.
Bunkers must also protect the inhabitants from normal weather, including rain, summer heat and winter cold. A normal form of rainproofing is to place plastic film on the bunker's main structure before burying it. Thick (5-mil or 0.13 mm), inexpensive polyethylene film serves quite well, because the overburden protects it from degradation by wind and sunlight.
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Famous installations
Famous bunkers include the World War II V-weapon installations in Germany (Mittelwerk), in France (e.g. La Coupole, and Éperlecques) and the Cold War installations in the United States (Cheyenne Mountain, Site R, and The Greenbrier) and Canada (Diefenbunker). The Soviet Union maintained huge bunkers (one of the secondary uses of the very deeply dug Moscow Subway system was as nuclear shelters), and in Albania, Enver Hoxha dotted the country with hundreds of thousands of bunkers. Dictators and potentates like Saddam Hussein often spent massive sums building fortresses beneath their palaces. Osama bin Laden at one time was also rumoured to be hiding in massive 'underground fortresses' in Tora Bora, though these would only be natural features strengthened and extended to some degree.
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See also
General topics:
- Air-raid shelter
- Blast shelter
- Blockhouse
- British Field Defences of WWII
- Bunker buster
- Earth sheltering
- Fallout shelter
- Flak tower
- Hesco bastion
- Observation post
- Martello tower
Specific bunkers:
- Bankstown Bunker, an Australia air defence headquarters bunker in Sydney, Australia
- Burlington, a city-sized bunker beneath Wiltshire, United Kingdom
- Cheyenne Mountain, the underground base of NORAD
- Führerbunker, the Berlin bunker of Adolf Hitler
- World War II line-type bunker systems
- Atlantic Wall, coasts of Western Europe, built by Nazi Germany during WWII
- GHQ Line, southern England, built by Great Britain during WWII
- Maginot Line, eastern France, built by France, pre-WWII
- Siegfried Line, western Germany, built by Germany during WWI and again pre-WWII
- Taunton Stop Line, southwest England, built by Great Britain during WWII
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References & Notes
- ^ Albania's Chemical Cache Raises Fears About Others - Washington Post, Monday 10 January 2005, Page A01
- ^ An archival look at World War I (from the Queen's University Archives, Kingston, Ontario, Canada. Accessed 2008-02-10.
- ^ Why Pillbox? - Hellis, John; an article from the Loopholes journal with further references. Retrieved 2007-09-08.
- ^ Accueil (from the Muse du Mur de l'Atlantique d'Audinghen website, in French. Accessed 2008-02-10.)
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External links
- Bunkers or bunker systems:
- Europe Bunker Pictures (images, locations and information, mainly Atlantikwall, also some about Cold War structures)
- Europe WW2 bunkers in Europe (reference website about museums and sites of WW2 pillboxes, bunkers and other defensive structures with maps and photos)
- Great Britain Coastal Defences North Norfolk (image collection of WW2 coastal defences)
- Great Britain Pillboxes UK (reference website about WW2 pillboxes and other defensive structures)
- Great Britain UK Heritage: Pillboxes (short article about "Miniature modern castles")
- Great Britain Subterranea Britannica: Cold War (information on Cold War-era underground structures in Britain)
- Italy Some [German] Fortifications Observed in Italy (a WWII intelligence Intelligence Bulletin report including photos)
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