Our unrivalled track record in soft ground tunnels spans over 100
years, from our initial involvement in the City and South London
Railway right through to the present day. This experience covers
all forms from the simplest hand mined construction to today's
highly mechanised methods employing sophisticated TBMs.
Heathrow Express rail link extension to Terminal 5
includes 1.3km of twin tunnels built by open faced TBM in London
Clay Our soft ground tunnels have been successfully
constructed below dense urban areas and under deep sea channels.
The means to control the settlement of the ground is fundamental to
the success of urban tunnels and our portfolio includes the use of
compensation grouting, freezing, dewatering, compressed air
working, slurry shields and earth pressure balance TBMs.
Urban and undersea tunnels
Our specialist services in soft ground tunnelling cover TBM
specification, settlement analysis and building/structure response
to ground movement, instrumentation and monitoring, along with
economic assessment, cost estimating and construction supervision.
In addition we specialise in designing and specifying the
appropriate tunnel lining – be it segmental, sequential excavation
method, or cast in situ concrete. We can lay claim to having
invented and developed the first slurry shield used in the UK in
1971, and more recently Mott MacDonald has pioneered the
application of sequential excavation method (or NATM) in soft
ground, including the largest excavation formed in London Clay for
the Heathrow Express cross-over cavern.
Piccadilly Line underground railway extension at
Heathrow , UK
Notable soft ground tunnel projects engineered by Mott MacDonald
include:
- Greater Cairo Wastewater Project, Egypt
- New St Clair River Rail Tunnel, USA/Canada
- Jubilee Line Extension, UK
- Bangkok Water Supply Tunnels, Thailand
- Great Belt Eastern Railway Tunnel, Denmark
- Heathrow Express Rail Link, UK
- Vibhavadi Rangsit Cable Tunnels, Bangkok
- Mission Valley LRT San Diego, USA
- Dulles Airport People Mover, USA
- Delhi Metro, India
- Heathrow Airside Road Tunnel, UK
