Editing London deep-level shelters (section)

==Background==
Each shelter consists of a pair of parallel tunnels {{convert|16|ft|6|in|m}} in diameter and {{convert|1200|ft|m}} long. Each tunnel is subdivided into two decks, and each shelter was designed to hold up to 8,000 people. It was planned that after the war the shelters would be used as part of new express tube lines paralleling parts of the existing [[Northern line|Northern]] and [[Central line (London Underground)|Central line]]s. Existing tube lines typically had {{convert|sigfig=3|12|ft|2.5|in|m|adj = on}} diameter running tunnels and about {{convert|21|ft|m}} at stations; thus the shelter tunnels would not have been suitable as platform tunnels and were constructed at stations the new lines would have bypassed. However, they would have been suitable as running tunnels for main-line size trains. (One existing tube, the [[Northern City Line]] opened in 1904, used a similar size of tunnel for this reason, although in fact main-line trains did not use it until 1976.)

Ten shelters were originally planned, holding 100,000 people — 10,000 in each shelter. However, the final capacity was around 8,000 people in each shelter, and only eight were completed: at [[Chancery Lane tube station|Chancery Lane]] station on the Central line and [[Belsize Park tube station|Belsize Park]], [[Camden Town tube station|Camden Town]], [[Goodge Street tube station|Goodge Street]], [[Stockwell tube station|Stockwell]], [[Clapham North tube station|Clapham North]], [[Clapham Common tube station|Clapham Common]], and [[Clapham South tube station|Clapham South]] on the Northern line. The other two were to be at [[St Paul's tube station|St Paul's]] station on the Central line, which was not built because of concerns about the stability of the buildings above, and at [[Oval tube station|Oval]] station on the Northern line, not built because of difficult ground conditions encountered as the work started. The working shaft for the shelter at Oval now functions as a ventilation shaft for the station.<ref>{{cite web|url=http://www.subbrit.org.uk/rsg/features/deep_level_shelters/index.html |title=Abandonment of St Paul's and Oval shelters |publisher=Subbrit.org.uk |date= |accessdate=2010-05-24}}</ref>

The shelters were started in 1940 during [[the Blitz]] in response to public demand to shelter in the London Underground stations. However, they were not completed until 1942 after the Blitz was over, so they were initially all used by the government, but as bombing intensified five of them were opened to the public in 1944: Stockwell, Clapham North, Camden Town, Belsize Park and Clapham South. The Goodge Street shelter was used by [[Dwight D. Eisenhower|General Eisenhower]], and the Chancery Lane shelter was used as a communications centre.