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Channel Tunnel vs Eden Project

Channel Tunnel or Eden Project? You can decide which has been the best construction project of the last 20 years.

Marking the 20th anniversary of the British Construction Industry Awards, the best projects of the past 20 years will be honoured with a special award at the gala awards dinner in London on 10 October.

Over the last 12 weeks NCE readers have been attempting to influence the judges’ choices by voting for their favourite. More than 4,000 votes have been cast to date, allowing us to whittle the contenders down to the final two – the Eden Project and the Channel Tunnel.

Already fallen by the wayside are stellar projects including the High Speed 1, Sizewell B, the Tate Modern, the Second Severn Crossing, the Jubilee Line extension and the Cardiff
Bay Barrage. There is now one week for readers to make their voices heard for their favourite.

So vote now!

The Eden Project

The Eden Project was the BCIA Major project winner in 2001. This visionary Ł57M scheme transformed a disused china clay pit in Cornwall into the world’s largest greenhouse. The Eden Project has subsequently been further extended and become one of the UK’s best-known attractions.

The project is instantly recognisable by its distinctive biome structures Đ the tallest of which is 55m high. This comprises steel space frames supporting ethyltetrafluoroethylene (ETFE) foil glazing. The two biome structures comprise four connected geodesic domes based on a grid of hexagons. The domes enable the structure to be completely self supporting. The glazing has a double skin of ETFE that is gently pressurised to stiffen each hexagon panel and improve thermal performance. The lightweight material allows longer glazing spans of up to 11m increasing the amount of light flowing in.

BCIA judges praised the project team including architect Grimshaw, structural engineer Anthony Hunt Associates and contractors Sir Robert and Alfred McAlpine for overcoming a considerable cut in the project’s original budget. They also had to tackle difficult ground conditions which often reduced the construction site to a “quagmire”.

The BCIA judges said of the project: “Eden is on a vast scale and is delivered with unswerving and brilliant vision, executed with the best modern design and engineering in Europe Đ the entire gamut of industry skills, from geotechnics to fit outs, is apparent in this tour de force of design and construction. Eden was against the odds but those involved made it happen Đ It is brilliant in concept, vision and construction and a major attraction in the south west.”

Channel Tunnel

The Channel Tunnel was the realisation of a 200-year dream to connect England with France and was a civil engineering achievement of historic proportions. Engineers designed and built 50km of triple bore tunnel, 39 km of which is under water, making it the longest undersea tunnel in the world. It won the BCIA Special Award in 1994 “for an outstanding feat of civil engineering”.

Tunnel boring machines (TBMs) worked simultaneously from the French and English sides through a a single chalk stratum at an average of 45m below the seabed. Working from each side of the English Channel, the TBMs for the 4.8m diameter service tunnel met in 1990. The TBMs for the main tunnels broke through in 1991. The tunnelling operation saw 8M.m3 of soil excavated at an average of 2,400 tonnes an hour. Much of the excavated soil on the English side was used to reclaim 360m2 of land near Folkestone, which is now a popular park.

The twin 7.6m diameter running tunnels linking to the 4.8m service tunnel were driven in just over three years. The construction consortium Transmanche Link, included UK firms Balfour Beatty, Costain, Taylor Woodrow, Tarmac, and Wimpey.

Despite the fact that the project ran 80% over budget with an estimated final cost of around Ł10bn, the BCIA judges praised the project team for bringing a “dream to reality”.

“Breathtaking though they are, the statistics alone cannot convey the awesome magnitude of the undertaking or the challenge of bringing it to fruition. The judges salute all those who played a part in turning the dream into reality.”

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