The first of 38 steel beams have completed their 560-mile journey from Eiffage Metal’s workshop in France to the English Chilterns on the back of extra-long lorries.
HS2 says that each of the 40-tonne beams is made of steel that is designed to naturally weather to a dark brown colour over time and blend into the countryside. (The uninformed might think they’ve just gone rusty.)
Located south of the village of Wendover in Buckinghamshire, the 450-metre-long viaduct will be the first major railway bridge in the UK to be built with a double composite structure. Two steel girders will be sandwiched between two layers of reinforced concrete for maximum strength and minimum weight.
It is one of 50 viaducts on the first phase of the HS2 high speed railway line between London and the West Midlands. It is being built by EKFB, a joint venture of Eiffage, Kier, Ferrovial and BAM Nuttall, HS2 Ltd’s main works contractor for the 80km section between the Chiltern Tunnel and Long Itchington Wood.
Over the summer EKFB will assemble the beams into the first of five 90-metre long spans. Pre-cast concrete sections will then be added to form the box-like structure. These will then be pushed out from the north abutment onto each of the concrete piers later this year.
HS2 Ltd project client Neil Winterburn said: “It’s great to see the first beams arrive on site. These huge pieces of steel will play a vital role in the innovative double composite structure of the viaduct deck – and help us cut the amount of embedded carbon in the structure.”
EKFB worked with its design partner ASC (a joint venture between Arcadis, Setec and Cowi) and specialist architect Moxon on the viaduct design, which was inspired by structures on the French high speed TGV network. As well as manufacturing the steel, Eiffage Metal is also leading on the installation of the beams.
EKFB senior engineer James Collings added: “There's been a tremendous amount of effort put in to get to this stage of construction, including an extensive earthworks and utilities programme and beam delivery is a key milestone for the team.
“As momentum gathers pace and we continue our preparations for the bridge deck launch, it’s great to see these steels on site, ready for the next phase of build. We’re starting to see the viaduct emerge from its foundations and start to take shape above ground.”
Construction has also begun on the piers – some up to 14 metres high – that will support the deck of the viaduct. These are made of a series of hollow pre-cast concrete shells that are placed on top of each other and filled with concrete and steel reinforcement.
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