The last of over 290 concrete piles that will form the foundations for the UK's longest railway bridge have been installed at the site of HS2's Colne Valley Viaduct.

Once complete, the 2.1 miles (3.4km) bridge will carry the new high-speed rail line across a series of lakes and waterways near Hillingdon on the north-west outskirts of London.

The construction of the foundations, the 56 huge piers and the deck on top, have all been happening in parallel – with separate teams working from north to south. Deck assembly began last year, with more than 500 meters of the viaduct structure now complete.

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In order to deliver the 66 piles in the lakebed, the team first had to construct over a kilometer of temporary jetties, with cofferdams to hold back the water around each set of foundations. The jetties are also used to transport materials and equipment during the construction of the piers and viaduct deck, keeping vehicles off local roads.

Construction of the HS2 project - which is designed to improve rail links between London, Birmingham and North, help level-up the economy and provide a low carbon alternative to car and air travel - is ramping up across the UK with almost 30,000 jobs now supported by the project.

HS2 Ltd's Project Client, David Emms said: "Once complete, HS2 will transform journeys across the UK, help to boost the economy and support the UK's transition to net zero.

"The completion of the piling for the Colne Valley Viaduct is a major achievement for our whole team and marks the end of almost two years of hard work. With pier construction and deck assembly also well underway, the viaduct is fast becoming one of the most impressive and recognisable parts of the project."