UTILIZED SOFTWARE 

PLAXIS

LOCATION 

UK

ORGANIZATION/COMPANY 

Wentworth & Keltbray

In the heart of the City of London, Wentworth and Keltbray faced a problem that had no easy answer: excavating an 18-meter-deep basement immediately beside live roadways and active utilities, while underpinning and suspending the Grade I listed medieval All Hallows Staining Church Tower. Spatial constraints made it harder still — a corner prop clashed directly with the slip-form rig of the new concrete core, putting the schedule at risk.

Rather than absorb that risk in extra material and heavier temporary works, the team modeled its way out of it. Using PLAXIS, engineers simulated soil-structure interactions in detail, predicting ground movements precisely enough to protect adjacent services and optimize the design of temporary sheet pile walls and prop loads. Section sizes in the temporary works were tuned rather than over-specified, saving substantial material. A temporary reinforced-concrete ring beam safely carried the historic tower, and real-time strain gauge monitoring fed back into the geotechnical models, enabling an observational approach that allowed the clashing prop to be removed early and de-risked a critical path activity.

The sustainability outcome is measurable. Phase 1 carbon tracking came in at 52 kgCO2e/m2, beating the RIBA Stage 4 target of 54 kgCO2e/m2 — a reduction achieved not through offsetting, but through leaner engineering. Material waste was minimized, live utilities and urban ground stability were safeguarded, and a national heritage asset was preserved rather than compromised.

The social return matters as much as the carbon one. The design protected a listed church tower that has stood for centuries and unlocked new public realm space, strengthening the cultural and social fabric around the site. Delivered collaboratively by Arup and Wentworth on a project valued at £73.8 million and targeting completion in November 2026, it shows how analysis-led design turns constraint into lower-carbon, higher-value infrastructure.