A hole has been drilled in the exposed crown of the Connaught Tunnel, which runs beneath the Royal Victoria Dock, following work to drain 13 million litres of water from a section of the docks that lie above.
Work will now continue to open up a hole that will eventually measure approximately 20 metres long and 10 metres wide to allow for the engineering equivalent of 'open heart surgery' to strengthen, deepen and widen the central section of the tunnel so that it can accommodate Crossrail's trains.
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Sections of the tunnel are in a poor condition and parts of it were narrowed during the 1930s so that the dock could be deepened to accommodate larger ships with brickwork removed and steel segments installed. The hole in the crown of the tunnel will allow Crossrail to remove much of this material and to continue with the process of ensuring that the tunnel is safe and ready for the arrival of the new trains.
Over the last few months a cofferdam measuring 1300 sq. metres, around the size of four tennis courts, has been put in place to allow a section of the Royal Victoria Dock to be drained so that Crossrail workers can access the tunnel from above. During the draining of the dock, a total of 332 fish were removed and safely relocated on either side of the cofferdam.
The tunnel was built in 1878 and has not been in passenger use since December 2006. It is the only existing tunnel that will be re-used for Crossrail.
