Friday, March 09, 2007

Construction of sub-sea tunnel in The Palm

The real estate major Nakheel, the company behind the developing Palm Jumeirah, has announced the construction of a sub-sea tunnel which links the center of the Palm and the Crescent. The tunnel which has six lanes is 1.4 kilometeres in length, 25 metres below sea level and is 40 metres in width. The tunnel comprises of two cells for traffic with three lanes running in each direction, and an emergency cell in between.

To enable the tunnel construction, a long coffer dam (a dam which helps in excluding water from an area which is otherwise submerged) which is three kilometers in length was constructed during October 2004. The dam was constructed by lashing sheet piles deep into seabed. On construction of the dam, about 4.3 million cubic meters of sea water was removed at a speed of 1000 cubic meters per hour from the cofferdam within 45 days.

When the dam was free of water, the tunnel construction went underway. The construction of tunnel required 200,000 cubic meters of durable concrete, 260,000 cubic meters of sand back-filling and about 50,000 tonnes of rock armour.

Currently the work of monorail construction is being done on the tunnel. Polystyrene sheets are placed on top of the tunnel before firming up the piers in order to stabilize the weight.

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