LYCOS RETRIEVER 
Channel Tunnel: Construction
built 658 days ago
Although cross-channel traffic is increasing steadily, and the first tunnel covers its running costs, it has made slow progress in paying off its enormous debt from the construction. No-one is likely to be keen to build a second tunnel in the near future - so this feasabilty study will probably go no further.
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After local protests, early plans were modified to put much more of the track into tunnel up until a point approximately 1 mile from St Pancras. For example, the Link will now pass underneath in a tunnel, rather than alongside, the North London Line on approach into St Pancras. Previously, an elevated section had been expected. The CTRL Section 2 construction works have been causing considerable disruption around the Kings Cross area of London, but will bring in their wake much redevelopment. The huge redevelopment area includes the run-down areas of post-industrial and ex-railway land close to King's Cross and St Pancras.
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Digging the tunnel took 15,000 workers over seven years, with tunnelling operations conducted simultaneously from both ends. The prime contractor for the construction was the Anglo-French TransManche Link, a consortium of 10 construction companies and 5 banks of the two countries. Engineers used large tunnel boring machines (TBMs), mobile excavation factories that combined drilling, material removal, and the process of shoring up the soft and permeable tunnel walls with a concrete liner. After the British and French TBMs had met near the middle, the French TBM was dismantled while the British one was diverted into the rock and abandoned. Almost 4 million cubic metres of chalk were excavated on the English side, much of which was dumped below Shakespeare Cliff near Folkestone to reclaim 90 acres (360,000 m²) of land from the sea.
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The two sections of the service tunnel were the first to link up, breaking through in December 1990. The tunnelling companies were Graham Fagg of the United Kingdom and Philippe Cozette of France, and they achieved a tunnelling rate of 426 m (1,398 ft) in one week. A total of 7 million tonnes of spoil was removed. At the peak of activity, 15,000 construction workers were on site.
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The main element of tunnel works in this phase was the construction of the North Downs Tunnel. The 3.2km tunnel was constructed beneath the North Downs with up to 100m of cover through upper, middle and lower chalk. The Contractor for the Contract 410 was a joint venture between Miller Civil Engineering, Dumez-GTM, and Beton und Monierbau who used shotcrete to provide the primary lining. An important feature was having RLE's designers on site that enabled value engineering to be evaluated and implemented in advance of construction. The main value engineering initiatives were:
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Digging the tunnel took 13,000 workers over seven years, with tunnelling operations conducted simultaneously from both ends. The prime contractor for the construction was the Anglo-French TransManche Link (TML), a consortium of ten construction companies and five banks of the two countries. Engineers used large tunnel boring machines (TBMs).
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