HS2 starts M42 bridge build with modular blocks

Work has begun on a 300-metre bridge to carry HS2 trains over the M42 motorway near Birmingham. HS2 has completed the first phase of preparation, enabling engineers to start building the “twin box” structure using modular pre-fabricated concrete blocks.

During two weekend closures and one night-time closure, engineers removed old concrete foundations, installed underground ducting, and prepared a central reservation work area. The bridge will allow the high-speed railway to cross a 130-metre stretch of the motorway between junctions 6 and 7/7a near the NEC and Birmingham Business Park.

The modular construction method involves using 1,500 hollow concrete blocks, each weighing an average of 14 tonnes. These blocks will be stacked and filled with concrete to form the walls, while 295 beams will span the gaps between the walls, supporting the bridge deck. The structure is expected to be completed by early 2027.

Oliver Shore, project director for 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. Using a modular construction method, this impressive structure will be built in position to minimise disruption on road users.”

To maintain traffic flow during construction, three lanes of the M42 will remain open with a 50 mph (80 km/h) speed limit. At peak activity, the project will employ 150 workers.

HS2, which now supports over 31,000 jobs, aims to improve connectivity between London, the Midlands, and the North while reducing congestion on the West Coast Main Line.