A major step in the construction of the Colne Valley Viaduct has taken a step forward with the completion of the first piers which will carry the viaduct over a series of lakes on the outskirts of London.
The Viaduct which is being built by HS2 will carry the high speed trains across the River Colne, Grand Union Canal and the Colne Valley Regional Park on a two-mile stretch, eventually meeting the start of the Chiltern tunnels near Denham.
For the last year, a 700-tonne ‘launch girder’ – the only one of its kind in the UK - has been assembling giant pre-cast concrete segments to form the first 1 km of the viaduct deck along the edge of the valley.
Now the first enormous v-shaped piers have been completed in the lake, to allow the viaduct to curve eastward, over the water. The ‘V piers’ – each weighing in at 1,800 tonnes – will support a row of elegant arches inspired by the flight of a stone skimming over the surface of the water.
Welcoming the milestone, HS2 Ltd Project Client David Emms said:
“The Colne Valley Viaduct will form a key part of the HS2 route – helping to deliver better connections across the UK, free up rail capacity on the existing network, and offer passengers zero carbon travel options.
“That’s why it’s great to see so much progress over the last 12 months and especially the completion of the piers that will allow the girder to head out over the lakes later this year.”
The launch girder, which was originally used during the construction of the Hong Kong East Tsing Yi Viaduct and is specially designed to cope with complex viaduct construction.
The ‘V piers’ are twice as large as simpler piers that carry weight over land and are cast in place using a series of giant moulds.
To hold back water during the construction, cofferdams were used to hold back the water while 60m deep foundations were built into the bed of the lake. In total, 11 ‘V piers’ will support the viaduct once finished.
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