Sitting at 3.4km in length, the Colne Valley Viaduct is set to become the longest railway bridge in the UK, as work officially begins on the construction. The bridge will cover over two miles across a series of lakes and waterways between Hillingdon and the M25.
Align JV are leading the viaduct construction – made up of Bouygues Travaux Publics, Sir Robert McAlpine and VolkerFitzpatrick. The bridge itself will be hoisted onto the concrete deck segments, which form the viaducts arches, using a machine known as a launching girder, a 160m long, one of a kind machine in the UK.
Originally built in 2004, the launching girder was first used during the construction of the Hong Kong East Tsing Yi Viaduct. Specially designed to handle complex viaduct construction, the machine is named ‘Dominique’ in memory of Bouygues engineer Dominique Droniou who played a leading role in its design and development.
A total of one thousand deck segments will be needed, with each one weighing up to 140 tonnes. To allow for the gentle curves of the viaduct as it crosses the valley, all the segments are slightly different shapes and made on site at a purpose-built temporary factory close to the north abutment.
HS2 Minister, Andrew Stephenson said:
“Today, HS2 began construction on what’s set to be Britain’s longest railway viaduct, a landmark moment for HS2 and a feat of British engineering, taking the HS2 line from London, and into Hertfordshire and Buckinghamshire.
“Infrastructure is the backbone of HS2 and this viaduct will be integral to delivering faster journeys and an increased capacity rail network.”
HS2 Ltd Chief Executive Mark Thurston said:
“I’m absolutely delighted that we have started work to assemble the giant deck segments that will form the Colne Valley Viaduct. It is yet another big milestone for HS2 Ltd, as we work to deliver the UK’s new high-speed railway. Once complete, this record-breaking structure will form a key part of the HS2 railway – helping to deliver better connections across the UK, free up rail capacity on the train network, and offer passengers a zero-carbon travel option.
“I’d like to thank all those involved in getting us to this exciting stage and look forward to seeing the whole viaduct come together over the coming years.”
56 piers each weighing around 370 tonnes are being constructed along the Colne Valley ahead of the girder, with the girder moving from one pier to the next, installing the deck segments as it goes. One segment is put in place each side of the central pier, using a cantilever approach to balance the structure, as two half-arches either side of each pier are constructed simultaneously. Steel tensioning cables will be threaded through the segments to strengthen the bridge.
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