Locale : Global (English)
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View of the terminal under construction

Heathrow Terminal 2B, London

Mott MacDonald provided geotechnical, civil and structural engineering for T2B, the UK’s largest-ever airside project. T2B includes a basement measuring 377m long, 15m deep, 60m wide at the ends and 100m wide in the middle.


Lean foundations design

We value-engineered our solution to achieve huge savings on earthworks excavation and reinforced concrete, compared to industry standard designs. The sides of a large basement are normally angled at 45° to prevent ground movement during excavation but site constraints required construction of a vertical retaining wall.

The embedment depth of the wall was reduced by 1.5m, saving 5000cu m on earthworks and concrete, and 700t CO2. We reduced the length of piled foundations by 10-20%, saving 6000cu m earthworks and concrete, and 850t CO2. And we reduced the thickness of the basement slab by a third over the majority of the terminal’s footprint, saving 7000cu m reinforced concrete and 1000t CO2. Excavated clay and gravel were reused locally. Existing pavement quality concrete was crushed and used on site, minimising carbon emissions associated with road haulage.

Savings contributed to a six months reduction in construction time and £25m in cost.

Client: Balfour Beatty for BAA/Heathrow Airport Limited

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