Commuters and residents at Watford Junction in Hertfordshire may be wondering what is happening at their station which is on the main London Midland Region line to Manchester.
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Background: Commuters and residents at Watford Junction in Hertfordshire may be wondering what is happening at their station which is on the main London Midland Region line to Manchester. During the past three to four weeks half a round underpass has been pushed through the railway embankment beneath the rail tracks, while trains and passengers have been going about their normal business.
In about two weeks time, the other half of the underpass will be pushed from the other side of the tracks and the two halves will meet in the middle to form an instant underpass to a new car park for railway users. The first half seen in this film, is approximately seventy feet long, twenty seven feet wide and twelve feet high and weighs over five hundred tons. This mass of reinforced concrete was cast on a specially prepared concrete bed which was anchored down into the chalk, forty feet beneath ground level to prevent it moving. The huge box was then slowly pushed forward by twelve hydraulic jacks exerting a total thrust of more than a thousand tons.
The sheet piling holding up the railway embankment was first cut through by burning with oxygen and the steel cutting shield attached to the front of the concrete box, cuts through the embankments, while spoil is removed from within as the drive proceeds.
The seventy ft long box was jacked at the rate of about nine inches an hour requiring very careful control of line and level, as the whole underpass is at a skew and the two halves must meet exactly. Soon a serious parking problem will be solved and life made easier for these commuters.
Pipe jacking carried out by Tube Headings Limited, a member of the Cementation Group of Companies.