Editing Box Tunnel (section)

===Construction===
The GWR selected George Burge of [[Herne Bay, Kent|Herne Bay]] as the major contractor,<ref name=NetRailBox/> being responsible for undertaking 75 per cent of overall tunnel length, working from the western end. Burge appointed [[S.H. and S.W. Yockney|Samuel Yockney]] as his engineer and manager.<ref>{{cite web |url=http://www.gracesguide.co.uk/Samuel_Hansard_Yockney |title=Samuel Hansard Yockney |publisher=GracesGuide.co.uk |access-date=2 March 2013}}</ref> Locally based Lewis and Brewer were responsible for the remainder, starting from the eastern side. One of Brunel's personal assistants, William Glennie, was in overall charge until completion.<ref name = "eng time"/>
[[Image:Network Rail Virtual Archive Box Tunnel.jpg|thumb|right|250px|An engineering drawing of the longitudinal cross-section of Box Tunnel]]

In December 1838, construction started. Work was divided into six sections; access to each was via a {{convert|25|ft | m | adj = mid |-diameter}}  ventilation shaft, which ranged in depth from {{convert|70|ft}} at the eastern end to {{convert|300|ft}} towards the western end.<ref name=NetRailBox/> The men, equipment, materials and {{convert|247000|cuyd}} of extract had to go in and come out of the shafts assisted by [[steam engine|steam-powered]] winches. The shafts were the safety exits from the tunnel.<ref name=NetRailBox/>

Candles provided the only lighting in the workings and were consumed at a rate of one tonne per week, which was equalled by the weekly consumption of explosives.<ref name=NetRailBox/> Due to the considerable time required for men to enter and exit the workings, [[Rock blasting|blasting]] took place while they were in the tunnel. This practice and water ingress exceeding the calculated volumes, has been attributed as causing most of the deaths that occurred. About 100 [[navvy|navvies]] were killed during the tunnel's construction. Additional pumping and drainage were required during and after its construction. Large amounts of water entering the tunnel in the winter months impeded progress.<ref name=NetRailBox/><ref name = "eng time"/>

Once the eastern section had been blasted out, it was cut to form a gothic arch and left unlined.<ref name = "eng time"/> The western section was excavated using picks and shovels and the walls were lined with brick. Over 30 million bricks were used which were manufactured in nearby [[Chippenham]]{{clarify|Chippenham?|date=September 2019}} and transported in horse-drawn carts. Horses were used to remove much of the spoil.<ref name = "eng time"/>

The restrictions imposed by the site contributed to a delay in the tunnel's completion. By August 1839, only 40 per cent of the works had been finished.<ref name=NetRailBox/> By summer 1840, the {{stnlnk|London Paddington}} to {{stnlnk|Faringdon Road}} section of the [[Great Western Main Line]] (GWML) had been completed, as was the track from [[Bath Spa railway station|Bath]] to {{stnlnk|Bristol Temple Meads}}. The Box Tunnel was the last section of the GWML to be finished, although not for lack of effort on the part of Brunel.<ref name = "eng time"/>

During January 1841 Brunel came to an agreement with Burge and Yockney to increase their workforce from {{formatnum:1200}} to {{formatnum:4000}}, and the tunnel was completed in April 1841.<ref name=NetRailBox/> The completed tunnel was {{convert|30|ft|||abbr=}} wide and capable of accommodating a pair of [[broad-gauge]] tracks. When the ends of the tunnel were joined, there was less than {{convert|2|in|mm|-1}} of error in their alignment.<ref name=NetRailBox/> Brunel was so delighted that he reportedly removed a ring from his finger and gave it to the works foreman.<ref name = "eng time">{{cite web |last1=Manolson |first1=Adam |title=Box Tunnel |url=http://www.engineering-timelines.com/scripts/engineeringItem.asp?id=38 |website=Engineering Timelines |access-date=13 June 2018 |archive-url=https://web.archive.org/web/20221103131608/http://www.engineering-timelines.com/scripts/engineeringItem.asp?id=38 |archive-date=3 November 2022 |url-status=dead}}</ref>