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Colne Valley Viaduct

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Colne Valley Viaduct

Construction of the UK’s longest railway bridge began this week, with an expert team of ground engineers 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 across a series of lakes and waterways on the north west outskirts of London, will be almost a kilometre longer than the Forth Rail Bridge and carry trains travelling at speeds of up to 200mph .

The Colne Valley is an area of diverse countryside with areas of parks, green spaces and reservoirs. Along with the River Colne and the Grand Union Canal, the valley is a well-used public space offering recreational opportunities for visitors to enjoy.

Set low in the landscape, the design was inspired by the flight of a stone skipping across the water , with a series of elegant spans, some up to 80m long, carrying the railway around 10m above the surface of the lakes, River Colne and 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. This design was chosen to enable views across the landscape, minimise the viaduct’s footprint on the lakes and help complement the natural surroundings.

Constructing the viaduct

Over the next year, engineers from HS2 Ltd’s main works contractor Align JV – a team made up of Bouygues Travaux Publics, Sir Robert McAlpine, and VolkerFitzpatrick – will construct 292 piles under the ground to support the viaduct piers.

On top of each group of piles – some of which will go up to 55m into the ground - a concrete pile cap will support the pier which will in turn support the full 6,000 tonne weight of the bridge structure above. Instead of hammering the piles into the ground, 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.

Over the last six years, HS2 has worked closely with Affinity Water and the Environment Agency to monitor water quality and agree working methods. These will be monitored by a team of specialist engineers during construction in order to protect the natural environment.

An extensive programme of test piling has already been completed with engineers sinking 12 piles at two locations with geological and structural data from these tests fed back into the design of the viaduct. This has resulted in a 10-15% reduction in the depth of the piles and associated time and cost savings.

Useful links

HS2 and Align, our main works contractor, held a series of community engagement events in summer 2019 to update residents and businesses on how plans have developed for the Colne Valley Viaduct. The exhibition boards below outline:

  • Introduction and feedback from March 2018 events
  • You said, we did on construction, landscape design, recreational opportunities, viaduct design and noise requirements
  • Colne Valley Viaduct construction
  • Landscape design
  • Colne Valley Viaduct design
  • March 2018 Events

    Below are the boards from the March 2018 community engagement events. The PDF exhibition boards below outline key design themes related to the following topics:

  • Click here to view or download the Colne Valley Viaduct Engagement exhibition boards, March 2018 (PDF, 9MB).
  • This engagement phase has finished

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