UK-based high-speed rail network developer High Speed 2 (HS2) Limited has commenced work on the Colne Valley Viaduct, the country’s longest railway bridge.
An expert team of ground engineers has sunk the first of almost 300 piles which will lay the foundation for the viaduct which will carry the high-speed rail line about 10m above the surface of the River Colne and the Grand Union Canal, in the north-west borders of London.
Around 56 piers will support the structure, with the broadest spans reserved for where the bridge will cross the lakes and narrower spans for the approaches.
HS2’s main works contractor Align JV, which includes Bouygues Travaux Publics, Sir Robert McAlpine, and VolkerFitzpatrick, will construct 292 piles under the ground to support the viaduct piers, over the next 12 months.
Before being assembled from north to south, the main deck of the viaduct will be manufactured in sections at a nearby temporary factory.
HS2 Central 1 project client Rohan Perin said: “The Colne Valley Viaduct will be one of HS2’s most iconic structures and it’s great to see work now starting in earnest. I’d like to thank the whole team for the huge amount of work they’ve done to get us to this point.”
Align project director Daniel Altier added: “I have no doubt that, once complete, the viaduct will become one of, if not the, most striking element of HS2 phase one. The way it will be constructed is going to be equally fascinating for engineers young and old. The sections for the deck will be fabricated at our main construction site to the west of London just inside the M25 and using a huge launching girder, the deck will be formed from north to south, along the line of the route, thereby keeping unnecessary construction traffic off the roads.”
The engineers have already completed an extensive programme of test piling by sinking 12 piles at two locations. The collected geological and structural data from these tests has resulted in a 10%-15% reduction in the depth of the piles, along with cost and time savings.