Box Tunnel

Box Tunnel is a railway tunnel in western England, between Bath and Chippenham, dug through the Box Hill. It was built for the original route of the Great Western Railway under the direction of the GWR's engineer Isambard Kingdom Brunel.

The tunnel is 1 mile 1452 yards (2,937 m) in length, straight, and descends a 1 in 100 gradient from the east. Construction started in 1836, and the tunnel opened in 1841. The lives of about 100 navvies (railway construction workers) were lost during construction. At the time of opening it was the longest railway tunnel in the world, though the Standedge Tunnel and several other canal tunnels were longer. The dramatic western portal, near Box, is designed in the classical style, but the eastern portal, at Corsham, has a plain brick face. When the two ends of the tunnel were joined underground there was found to be less than 2 inches (5 cm) error in their alignment.

Geographical Location

[The features are clearly visible in Google Earth. Given the distance between ventilation shafts a fourth one would be expected between the third one and the West portal but it is not visible in Google Earth. It may be obscured by shadows or it may have been covered over if it was deemed unnecessary.]
* East portal: coord|51.423685|N|2.20536|W|type:landmark_region:GB|name=Box Tunnel east portal
* Ventilation shaft: coord|51.42277|N|2.21303|W|type:landmark_region:GB|name=Box Tunnel ventilation shaft
* Ventilation shaft: coord|51.42176|N|2.22179|W|type:landmark_region:GB|name=Box Tunnel ventilation shaft
* Centre of tunnel: coord|51.42128|N|2.22617|W|type:landmark_region:GB|name=Box Tunnel (centre)
* Ventilation shaft: coord|51.42084|N|2.23010|W|type:landmark_region:GB|name=Box Tunnel ventilation shaft
* West portal: coord|51.41888|N|2.24698|W|type:landmark_region:GB|name=Box Tunnel west portal

Brunel's birthday

There is a story which states that Brunel deliberately aligned the tunnel such that the rising sun is visible through it on 9 April each year, his birthday. Opinions vary widely as to whether this is true. Angus Buchanan (2002, p. 269) writes:

:The alignment of the Box Tunnel has been the subject of serious discussion in the "New Civil Engineer" and elsewhere. I am grateful to my friend James Richard for making calculations which convinced me that the alignment on 9 April would permit the sun to be visible through the tunnel soon after dawn on a fine day.

On the other hand, it has been asserted that it is impossible to guarantee the effect on a particular calendar day, because the angle at which the sun rises on a given date varies slightly with the cycle of leap years. [Karlson (1999)] However, the sun subtends an angle of about half a degree, which is more than the year to year variation, and more than the field of view through the tunnel, so it quite possibly seems to fill the tunnel every year. It is also asserted that Brunel failed to account for atmospheric refraction and the effect is visible a few days too early. [Lushman (1999)]

Buchanan ("ibid.", p.226) concludes:

:...I have found no documentary evidence for the often-repeated story that Brunel aligned the Box Tunnel so that the rising sun shone through it on his birthday, even though careful examination shows that it could indeed do so, and it is certainly a good story.

It is tempting to think that with a suitable vantage point, the effect (if not Brunel's intentions) can easily be checked on 9 April. However, the appropriate point is in the middle of a high-speed railway line and is thus potentially very dangerous. Photographs of the effect have reportedly been taken with appropriate assistance from railway officials.

Defence use

The hill surrounding the tunnel had been extensively quarried, extracting Bath stone. During the 1930s a significant portion of the quarries were developed by Royal Engineers for the storage of munitions. This became known as the Central Ammunition Depot and served the ammunition requirements of much of the South of England. A Royal Air Force station was also established using one area of the tunnels, RAF Box, and during the war a fallback aircraft engine factory was established to the North of Box Tunnel.

To service the Central Ammunition Depot a spur line was opened, breaking off from the main line at the eastern end of the tunnel, entering alongside the main portal. This spur leads to two platforms within the quarries, used for the delivery and removal of munitions.

Following World War II portions of the Ammunition Depot were variously redeveloped to house the Central Government War Headquarters, RAF No1 Signal Unit, Controller Defence communication Network and the Corsham Computer Centre. Much of this has now been decommissioned with only Corsham Computer Centre remaining in the quarries.

See also

* List of tunnels in the United Kingdom

References

Notes

Sources

* Adley, R. (1988) "Covering My Tracks", Stephens, ISBN 0-85059-882-6, p. 54-77
* Buchanan, R. Angus (2002) "Brunel: The Life and Times of Isambard Kingdom Brunel", Hambledon and London, ISBN 1-85285-331-X
* Chittenden, Maurice (2005) [http://www.timesonline.co.uk/tol/news/uk/article584503.ece "For sale: Britain’s underground city"] , Times Online October 30 2005, www site [accessed 18 May 2007]
* Hennessy, Peter (2002) "The Secret State - Whitehall and the Cold War", Penguin Books, ISBN 0-14-100835-0
* Karlson, Stephen H. (1999) [http://venus.soci.niu.edu/~archives/TOMPAINE/feb99/0023.html "Re: Six More Weeks of Prelims"] , Northern Illinois University message board, posted 3 February 1999 [accessed 18 May 2007]
* Lushman, Rory (1999) [http://www.magonia.demon.co.uk/news/tunnels.html "The Box Hill Tunnel: An Anorak's Paradise or a Passage To Narnia?"] , Updated news article on : [http://www.magonia.demon.co.uk/arc/00/newmag.htm MAGONIA Online] , www site [accessed 18 May 2007]
* McCamley, Nick (2000) "Secret Underground City", Pen & Sword Books, ISBN 0-85052-733-3

External links

*
* [http://www.subbrit.org.uk/rsg/sites/c/corsham/ Subterranea Britannica] entry on the Corsham bunkers
* [http://www.bbc.co.uk/wiltshire/content/articles/2005/12/14/burlington_nuclear_bunker_feature.shtml Wiltshire's Secret Underground City: Burlington] Articles, interactive map and video tour from BBC Wiltshire