The first beams of a ‘Lego set’ viaduct for the HS2 high-speed railway line have been installed in Buckinghamshire.

A total of 72 huge beams will support the deck of the Thame Valley Viaduct near the Rabans Lane Industrial Area on the western outskirts of Aylesbury.

HS2 Ltd said two cranes lifted the first four of the 90-tonne beams into position on top of the viaduct piers like “giant Lego blocks”.

The company behind the new high-speed railway line has hailed the engineering of the viaduct as the “first of its kind in the UK to have all major elements manufactured off site”.

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The lighter-weight design of the beams is said to be inspired by viaducts on the Spanish high speed rail network.

HS2 Ltd claimed this approach reduces the carbon-intensive concrete and steel used, therefore “cutting its carbon footprint by around a third”.

The 880m long viaduct across the flood plain of the River Thame will carry HS2 services between London and Birmingham.

The viaduct is partially visible from Public Rights of Way to the south-west, however HS2 claims the underside of the viaduct will be 3m above the ground, meaning it is “set low into the landscape”.

HS2 Ltd also claimed that manufacturing elements of the viaduct off-site requires fewer lorries to deliver material to site, as well as cutting waste and reducing disruption for the community during construction.