HS2 ‘giant Lego’ M42 box structure: construction method insights for engineers
Reviewed by Joe Ashwell
First reported on New Civil Engineer
30 Second Briefing
Installation is starting on roof beams for an HS2 “giant Lego” box structure spanning both carriageways of the M42 near Solihull, creating a portal for the future high-speed rail line. The precast concrete box will be assembled adjacent to live traffic and slid or jacked into final position during motorway possessions, minimising long-term closures on this key West Midlands corridor. For designers and contractors, the scheme illustrates large-scale box construction over an existing dual three-lane motorway under tight possession windows and complex temporary works constraints.
Technical Brief
- Precast elements are described as “giant Lego”, implying repetitive modular units to simplify on-site assembly.
Our Take
In our database, HS2-linked pieces span both major civils (like this M42 structure in the West Midlands) and long‑term asset care, with at least two recent items on £1bn‑scale interim maintenance procurement, so constructability and future maintainability of highway interfaces will be under particular scrutiny.
The Solihull/M42 works sit against a backdrop of a formal review of HS2’s delivery model, with another recent article noting that HS2 exposes systemic weaknesses in UK megaproject governance; any disruption on a live motorway will be politically sensitive evidence of whether those lessons are being applied in real time.
Strabag UK’s acquisition of ground engineering specialist Van Elle, flagged in a related article that also references HS2, suggests that specialist foundations and temporary works capability around HS2 corridors in the West Midlands could increasingly be delivered through vertically integrated contractors rather than fragmented supply chains.
Prepared by collating external sources, AI-assisted tools, and Geomechanics.io’s proprietary mining database, then reviewed for technical accuracy & edited by our geotechnical team.
