Tunnels and underground structures
Tunnelled solutions provide a discreet option for transport and utility pathways that can reduce disruption, minimise visual impact and increase service life and whole-life value.
But each tunnel – from the smallest and simplest to the largest and most complex – has its individual challenges.
Whatever your tunnel project, it can benefit from our design expertise and practical understanding. We will ensure safety, efficiency and sustainability from the initial design through to project completion.
What can we do for you?
Our tunnelling heritage goes back more than 130 years. We use that experience to select exactly the right design and construction technologies for your project.
Use any method, in all conditions
Bored, drill and blast, cut and cover, immersed tubes, trenchless (micro-tunnelling, pipejacking and directional drilling), sprayed concrete lining, sequential excavation. You name the tunnelling method, we’ve used it. From hard rock and soft soil to seismically active regions, deep tunnels under high groundwater pressure or sub-sea tunnels under busy sea lanes, we’ve navigated our way through all types of ground conditions.
Apply innovative techniques
We’ve developed innovations and embraced new technologies to deliver subterranean structures, including the first use of precast concrete and bolted tunnel linings, which improved the speed, safety and cost of installation. We invented the bentonite slurry tunnel boring machine to enable soft ground tunnelling and have developed the observation method to improve the speed and safety of shaft and tunnel excavation. We’ve also made advances in sequential excavation and sprayed concrete linings, which are now the go-to solution for hydropower caverns, stations, crossover caverns and connecting passages.
Help cut carbon
We apply carbon management on all our projects, to help you pursue your decarbonisation goals. We’ve reduced the carbon footprint of tunnels worldwide and continue to innovate with materials and methods to deliver sustainable solutions.
Central Kowloon Route, Hong Kong. A 4km highway tunnel will link areas across Hong Kong’s populous Kowloon peninsula, helping to relieve congestion as well as reduce air and noise pollution.
Engineering advanced tunnels and underground structures
Our tunnelling teams work with owners, operators, contractors and investors to design and deliver transport, power and water tunnel projects around the world. We can take care of every stage of your tunnel project, from initial planning and feasibility studies through concept and detailed design, costing and specification, procurement, project management, construction management and supervision, to repair and maintenance.
Our experience
We are working with owners and contractors to plan, design and deliver subterranean structures across the globe:
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Alaskan Way Viaduct, Seattle, USAA 50-year-old elevated section of State Route 99 on Seattle’s waterfront has been replaced by a 3.2km-long, 17.3m-diameter double deck tunnel. It is one of the largest-diameter bored tunnels in the world, and our alignment reduced risk and project costs.
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Catskill-Delaware Aqueduct, New York, USAOur digital tools are helping to remediate a 148km aqueduct built more than 100 years ago to bring clean water to New York City. Our approach is helping to keep project costs down and minimise disruption to services.
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Central Kowloon Route, Hong KongA 4km highway tunnel will link areas across Hong Kong’s populous Kowloon peninsula, helping to relieve congestion as well as reduce air and noise pollution. We are providing design, engineering and construction supervision services across the eight contracts. To optimise planning and design, improve construction delivery, quality and safety, and provide smoother interface coordination, as well as to reduce waste, we are managing CKR as a digital project throughout.
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Elizabeth Line, London, UKOur 30-year journey to bring London’s newest rail line into operation included 42km of tunnels under the city’s streets and buildings. Our expertise in sequential excavation with sprayed concrete lining helped create vast subterranean caverns, measuring up to 17m high and 16.5m wide. And our innovative real-time site monitoring data and state-of-the-art 3D numerical analysis of ground movements enabled the 42m-deep Moorgate shaft – the deepest point on the line.
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HS2, UKWe are using digital tools on the UK’s high speed rail project to monitor ground conditions as work advances and recalibrate the design so that it better matches the reality. This has reduced the extent of the temporary works, producing radical improvements on cost, programme, safety and carbon.
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Kidston pumped hydropower storage, Queensland, AustraliaA former gold mine in Australia is being turned into a 250MW battery capable of powering 140,000 homes for up to eight hours. We’ve designed the overall project layout as well as the intake canal, water conveyance tunnels and shafts.
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London Power Tunnels, UKFrom feasibility to the design and construction of 32km of tunnels with 14 shafts, and the installation of 64km of high voltage cable, we are helping to improve power supply resilience for homes and businesses in Greater London.
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Ontario Line, Toronto, CanadaAt 15.6km long and with 15 stations, the line is the biggest of four current subway expansion projects for Toronto and will meet the increasing demand for sustainable public transport across the city. Our key inputs include producing the business case for the line and developing the reference design and technical requirements for the alignment, tunnels and stations.
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Parallel Thimble Shoal Tunnel, Virginia, USAThis design-build project will alleviate congestion on the existing 27km-long Chesapeake Bridge and Tunnel Crossing in Virginia.
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Regional Connector, Los Angeles, USADesign and construction of the 3.1km twin-bored tunnels had to navigate the challenges of earthquake risk and tangles of existing utilities to transform journeys for LA Metro passengers. Our scope of work also included three underground stations constructed using cut and cover, a sequentially excavated crossover cavern and three mined cross-passages.
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Thames Tideway, London, UKA 25km tunnel will divert combined sewer overflows away from the River Thames and convey them to a treatment works. Our work on the eastern section includes five shafts with depths of up to 60m, and two tunnels – one of 5.5km and a shorter one of 4.5km – through southeast London.
Daarwin (a partner solution)
Daarwin is an AI-powered solution for monitoring and predicting the behaviour of deep excavations, tunnels and earthworks. Its real-time analysis enables engineers to refine their designs as work advances, maintaining safety while unlocking opportunities for working faster and more resource-efficiently. Daarwin reduces risk and increases sustainability.
