Pile driving has started on the U.K.’s longest railroad viaduct, which will be part of the London–Birmingham high speed rail system, known as HS2. The Coine Valley viaduct, northwest of London, is set to carry HS2 for 3.4 km.

The Align joint venture of Bouygues Travaux Publics, Sir Robert McAlpine and VolkerFitzpatrick will sink 292 piles along the viaduct with 45, 60 and 80 m spans.

Align has also started precasting 112,000 tunnel lining segments ahead of launching HS2’s first two tunnel boring machines this summer.

Including 16 km of twin tunnels through the Chiltern Hills, Align’s $2.2-billion design-build contract covers 21.6 km of the roughly 225 km railroad.

The main deck of the viaduct will be constructed in sections at a temporary factory nearby before being assembled.