Channel Tunnel Rail Link (HS1)
Channel Tunnel Rail Link (CTRL) is a 67-mile long high-speed rail line running between London and the Channel Tunnel terminal near Folkestone. The £5.2bn link enables trains to run at 300km/hr between London St.Pancras and Gare du Nord in Paris. As part of this contract, two cut and cover tunnels were required near to the villages of Hollingbourne and Sandway. The initial proposal was to construct the tunnels as in-situ reinforced concrete box structures. However, following a value engineering exercise involving RLE, Reinforced Earth Company and the contractor, an alternative solution using precast concrete arch segments was accepted, the first of its kind over a high speed rail line. The longer tunnel at Hollingbourne covers a length of 360m, while Sandway tunnel measures 170m. Backfill cover to the crown ranges from 0.5m to 5.5m at the deepest section. The portals to the tunnels were formed from Reinforced Earth precast concrete headwalls and wingwalls. Erection of the first 170m length phase of the Hollingbourne tunnel was completed on schedule in just four weeks. The rapid construction, together with the efficient use of materials has produced a cost effective solution for these two significant structures.
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