Riba £130bn ‘Loop’ high‑speed rail: design and tunnelling lens for engineers
Reviewed by Joe Ashwell
First reported on New Civil Engineer
30 Second Briefing
Riba president Muyiwa Oki has proposed “The Loop”, a £130bn high-speed rail system encircling the UK and Ireland, conceptually inspired by Saudi Arabia’s 170km linear city project The Line. The vision links the North of England, Wales, Scotland, Ireland and Northern Ireland into a single continuous corridor, implying extensive subsea tunnelling and long-span bridge works across the Irish Sea. For engineers, the scale suggests HS2-level design speeds and alignments replicated over multiple jurisdictions, with major geotechnical, consenting and interoperability challenges.
Technical Brief
- Loop geometry around islands demands multiple long subsea rail tunnels with high water pressure and gas risk.
- Continuous corridor concept would require harmonised electrification, signalling and loading gauge standards across five jurisdictions.
- Irish Sea crossings introduce combined ship impact, scour, fatigue and seismic design checks for any major bridge options.
- High-speed coastal and offshore alignments increase exposure to climate-change-driven sea level rise and storm surge.
- Landfall sections at tunnel portals would need complex ground treatment in soft coastal and estuarine deposits.
- For similar transnational corridors, early treaty-level agreements on safety regimes and asset ownership have proven critical.
Our Take
Within our 667-item Infrastructure set, very few schemes match the proposed £130bn scale for The Loop, signalling that this sits more in the realm of long-term national visioning than near-term deliverable projects in the UK and Ireland.
Using Saudi Arabia’s The Line as a reference point suggests Riba is deliberately framing The Loop as a design-led, top-down megasystem; in practice, UK and Irish rail schemes in our coverage tend to advance as segmented corridors, which would likely be how any part of this concept is actually procured and built.
For regions like Wales, Scotland and Northern Ireland, a continuous high-speed Loop would imply a rare opportunity to hard-wire cross-border connectivity into early route and station planning, rather than retrofitting links as has occurred with most recent UK rail upgrades in our database.
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.
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