HS2 motorway works completed to prepare for new M42 ‘twin box’ build on edge of Warwickshire

During two weekend closures, the team of engineers worked around the clock to prepare the area for construction by removing pre-existing concrete foundations, installing underground ducting and creating a safe working area in the central reservation of the motorway.

Once built, the M42 motorway box structure will measure 300 metres in length and will enable the high-speed line to cross over a 130-metre stretch of the M42 between junctions 6 and 7/7a near Birmingham Business Park and the NEC.

The structure will be built using a modular construction method which reduces the need for lengthy motorway closures, minimising disruption to road users. It involves the assembly of giant building blocks that are manufactured away from site and transported to land next to the motorway.

Some 1,500 hollow blocks, each weighing 14 tonnes on average, will be placed on top of each other, like bricks, before being filled with concrete to form the walls of the structure.

And 295 beams will bridge the gaps between these walls, followed by the installation of a bridge deck and parapets – with the structure due for completion in early 2027.

Work can now begin on the build process following two temporary weekend closures and one weekday night-time closure of the M42 to allow for essential preparation work.

Working in collaboration with National Highways, HS2 will build the structure in position while keeping three lanes of carriageway open on the M42, with a 50mph speed limit in place.

Doug Barnett, senior project manager for HS2 Ltd, said: “I would like to thank motorists for their patience and our colleagues at National Highways for their support during these recent temporary closures of the M42.

" I also commend our site team who worked through the night to complete this essential work, enabling the motorway to reopen five hours earlier than planned.

“Following this first phase of work, we can now start to build the structure in place from the ground up.

"We’ve prioritised a modular, self-supporting construction method as this avoids the need for any long-term motorway closures and reduces the overall construction time frame – keeping disruption to a minimum.”

HS2 and its main works civil contractor for the West Midlands, Balfour Beatty VINCI (BBV), will continue to work in partnership with National Highways as the build gets underway. At peak construction, a dedicated workforce of 150 will support the complex operation.

Oliver Shore, project director at Balfour Beatty VINCI, said: “Now we’ve completed essential preparation works along a section of the M42, we’re ready to begin building this twin box structure which will carry HS2 trains over the motorway.

"Using a modular construction method, this impressive structure will be built in position, to minimise disruption on road users.”

HS2 will be Britain’s new high-speed rail line.

HS2 Ltd has said that, once complete, it will almost halve the journey time between London Euston and Birmingham to just 49 minutes, with trains running north via the existing rail network to destinations such as Manchester, Liverpool and Glasgow.