UK’s longest rail viaduct project will see close to 300 piles sunk to depths of 55m

HS2 has begun work on the UK’s longest railway bridge, with contractors sinking the first of almost 300 piles that will form the foundations for the Colne Valley Viaduct.

The viaduct, which will carry the new high-speed rail line for 3.4km on the north-west outskirts of London, will be almost a kilometre longer than the Forth Rail Bridge in Scotland.

The Grimshaw-designed viaduct includes a series of spans, some up to 80m long, carrying the railway around 10m above the surface of lakes, the River Colne and the Grand Union Canal.

The structure will be supported by 56 piers, with the widest spans reserved for where the viaduct crosses the lakes and narrower spans for the approaches. The design was chosen to enable views across the landscape, minimise the viaduct’s footprint on the lakes and help complement the natural surroundings.

Main contractor on the job is the Align joint venture, a team of Bouygues, Sir Robert McAlpine and VolkerFitzpatrick. Over the next year, Align will sink 292 piles into the ground to support the viaduct’s piers. Piles will be driven up to 55m into the ground and instead of being hammered, holes will be bored before being backfilled to create the pile.

The main deck of the viaduct will be built in sections at a temporary factory nearby before being assembled from north to south.

Last week Grimshaw heard that ministers want it to scale back its designs for the HS2 terminus at Euston.

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