UK-based High-Speed Two (HS2) has announced the completion of the box ‘bridge slide’ over the M42 in Warwickshire.

Balfour Beatty VINCI (BBV), HS2’s construction contractor in the Midlands, slid a 12,600-tonne bridge by 165m to place it across a motorway.

The 86m long Marston Box bridge, developed by a design joint venture of Mott MacDonald and SYSTRA on behalf of BBV, was constructed on land next to the motorway over the last six months.

The structure has a base, three walls and a top slab.

Designed by civil and structural engineering company Freyssinet, the sliding mechanism enabled to push the box to place over the motorway on a guiding raft over a distance of 163m.

After being fully completed, the whole structure will be about 190m in length and can carry HS2 over the motorway as it heads north to Crewe.

The structure will also help HS2 carry on its southward journey as it loops into Birmingham Curzon Street or continues straight on to Interchange Station in Solihull, Old Oak Common Station and London Euston.

Upon construction, the railway bridge will link to Dunton Wood Embankment to the south and the Birmingham and Fazeley Canal Viaduct, which crosses the heritage canal, to the north.

HS2 civils delivery director Mike Lyons said: “This is the first box slide of its kind over a motorway in the UK, and we believe it’s also the world’s longest slide, so it’s a great achievement for HS2 as we quickly approach peak construction.

“It’s fantastic to celebrate another big milestone for a project that is already providing work for almost 30,000 people today, and in the future, it will encourage people to use zero carbon public transport.”