Box Tunnel

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Box Tunnel is a railway tunnel in Western England, between Bath and Chippenham, dug through Box Hill, and is one of the most significant structures on the Great Western Main Line. It was originally built for the Great Western Railway under the direction of the GWR's engineer Isambard Kingdom Brunel.

Winter overview of western portal
West portal
East portal with the quarry entrance clearly visible on the right

The tunnel is 1.83 miles (2,937 m) in length, straight, and descends a 1 in 100 gradient from the east. Construction started in 1836, and 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 a grand classical style, while the eastern portal, at Corsham, has a more modest brick face with rusticated stone. When the two ends of the tunnel were joined underground there was found to be less than 2 inches (50 mm) error in their alignment.

Box Tunnel is to be electrified with catenary as part of the GWML electrification scheme which includes service to Bristol Temple Meads and is scheduled for completion around 2016.[1]

Contents

[edit] Geographical location

[edit] 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.[2] 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.[3]

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[citation needed].

A similar situation exists with the Voortrekker Monument in Pretoria, South Africa. At midday on the Day of the Vow, the sun (if the weather is clear) shines straight down onto a stone with the Afrikaans inscription, "Ons vir jou, Suid-Afrika" ("Us for you, South Africa").

[edit] 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.

West portal of the Stapleford Miniature Railways tunnel complete with 1/5 GWR Saint class

[edit] See also

[edit] References

[edit] Notes

  1. ^ Department for Transport (2009). Britain's transport infrastructure: Rail electrification. London: DfT Publications. pp. 30. ISBN 978-1-84864-018-4. http://webarchive.nationalarchives.gov.uk/+/http://www.dft.gov.uk/pgr/rail/pi/rail-electrification.pdf. 
  2. ^ Karlson (1999)
  3. ^ Lushman (1999)

[edit] Sources

[edit] External links

Wikimedia Commons has media related to: Box Tunnel

Coordinates: 51°25′17″N 2°13′34″W / 51.42128°N 2.22617°W / 51.42128; -2.22617

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