Building the UK’s longest railway bridge

This short video takes you behind the scenes on a night shift with the HS2 engineers building the UK’s longest railway bridge – the Colne Valley Viaduct.

In October 2022, engineers installed the 99th individual viaduct deck segment, completing the fourth 80 metre span of the bridge, as it crosses the A412 in Denham. Over 300 metres of the Colne Valley Viaduct has now been completed. 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.

Stretching for more than 3.4km (2 miles) between Hillingdon and the M25, the Colne Valley Viaduct will be the longest railway bridge in the UK. When complete, the viaduct will carry the new high-speed line across a series of lakes and waterways on the north west outskirts of London, and will be almost a kilometre longer than the Forth Rail Bridge.

The huge viaduct project is being led by HS2’s main works contractor Align JV – a team made up of Bouygues Travaux Publics, Sir Robert McAlpine and VolkerFitzpatrick.

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Source: HS2