M42 box

The M42 Twin Box structure will carry the new HS2 line across the M42 near Birmingham Business Park and the NEC in Solihull. The new structure will measure approximately 300m length by 25m width and will cover around 130m of the M42. The structure will be built in position while keeping three lanes of traffic open on the M42.

Box construction

The construction of the M42 Box structure started with the demolition of two pre-existing bridges in August 2023 and February 2024 followed by the installation of traffic management in July 2024 to create a safe working environment for our workforce and road users.

As our programme progresses, we now need to carry our preparatory work to enable construction of the box structure which cannot be completed around live traffic. This preparatory work includes the demolition of existing pile caps and the installation of ducts under the carriageway.

Box design

The design uses prefabricated concrete blocks in a method called Design for Manufacture and Assembly, to significantly reduce the construction time frame. The blocks are placed upon one another like bricks before being filled with concrete to form walls with the strength required to carry the high-speed trains across the M42 Motorway. 295 beams will bridge the gaps between these walls before the installation of the bridge deck and rail.