Britain on Thursday finished building its longest-ever rail bridge after fitting the final segment of the Colne Valley Viaduct for the new high-speed HS2 train line, company bosses announced.

The curved 3.4 kilometer-long structure northwest of London is set to carry high-speed trains running to and from the capital at speeds of up to 320 kilometers per hour, HS2 Ltd said in a statement.

It surpasses in length the 3.3-kilometer Tay Bridge linking Fife and Dundee in Scotland, a record that stood since 1887.

"Lowering the Colne Valley Viaduct's final deck segment into place today marks the culmination of more than 10 years of planning, design and construction," said HS2 senior project manager Billy Ahluwalia.

The bridge is made of 1,000 pre-cast segments which support its 54 arches and that will carry the high-speed line up to 10 meters above land and water.

The HS2 project has been mired in controversy owing to spiraling costs that saw the previous Conservative government axe key legs of the railway planned for northern England.

Originally to have run between London in southeast England and Manchester in the north, the project was drastically altered last October.

That came after the project's costs almost trebled to more than an estimated £100 billion ($132 billion), in part owing to a surge in inflation.

The remaining route, linking London to Birmingham, is not expected to open until 2029 at the earliest—and could still end up costing £67 billion, according to an official estimate made in February.

At the same time, parliament's cross-party Public Accounts Committee strongly criticized the scaled-down plans, claiming they delivered "very poor value for money".

High Speed 2 is Britain's second such fast track, after the line that carries Eurostar trains from London to the Channel Tunnel, which in turn links the country with France.

© 2024 AFP