Underground construction
What is underground construction?
Underground construction covers the full range of engineering works carried out below ground level, including tunnel excavation, underground structures, utility network installation, and the creation of subterranean spaces for civil, industrial, and infrastructure projects.
As a specialist discipline within civil engineering, it requires detailed ground investigation, structural design, excavation planning, and permanent works installation, all within environments that present distinct geotechnical, safety, and logistical challenges.
Tunneling GLT delivers professional underground construction services for infrastructure owners, principal contractors, and development programmes. Our teams work across a wide range of project types and ground conditions, applying the most suitable construction methods to achieve safe and efficient results.
Underground construction services
Tunneling GLT delivers underground construction across the principal categories of subterranean infrastructure. Each project is managed under a structured programme with qualified engineering supervision, certified plant operators, and a documented safety management system applied from mobilisation through to handover.
Tunnel construction & excavation
The construction of tunnels for transport, utility, or infrastructure purposes demands a structured approach to face support, ground reinforcement, primary lining installation, and waterproofing. Tunneling GLT executes underground excavation works using both drill-and-blast and mechanised methods, adapting the construction approach to the geotechnical profile of each project.
Underground utility construction
The installation of below-ground utility networks — including water mains, gas distribution pipelines, electrical cable systems, and telecommunications ducting — requires precise excavation control, network operator coordination, and strict adherence to safe digging protocols. Our underground utility construction teams manage the complete scope from trench excavation or trenchless installation through to pressure testing and surface reinstatement.
Trenchless underground construction
Where open excavation is impractical, restricted, or prohibited — beneath active roads, railway infrastructure, waterways, or protected environments — Tunneling GLT deploys trenchless construction methods including horizontal directional drilling (HDD), pipe jacking, and microtunneling. These techniques allow underground structures and utility crossings to be constructed with minimal surface disruption, reduced traffic management requirements, and lower environmental impact compared with conventional open-cut methods.
Underground civil structures
Beyond linear tunnel drives, underground construction encompasses the design and build of below-ground civil structures — including underground stations, shafts, basements, and subterranean chambers for infrastructure, industrial, and public use. Tunneling GLT provides structural underground construction capability for complex subterranean projects requiring specialist temporary works design, ground support engineering, and permanent structure installation.
Multi-Utility & infrastructure packages
For major development programmes and infrastructure corridors, coordinated multi-utility underground construction delivers significant programme efficiency by consolidating gas, water, power, and telecoms installation within a single managed scope. Tunneling GLT provides integrated underground construction packages for principal contractors and infrastructure promoters, coordinating across utility disciplines to minimise excavation footprint, reduce ground reinstatement costs, and simplify programme management.
Types of underground construction projects
Tunneling GLT’s underground construction capability is applied across a broad spectrum of project categories. The following sectors represent the core of our project portfolio and reflect the range of environments, ground conditions, and client types we serve.
Transport tunnels & metro infrastructure
Highway & road
crossings
Water & wastewater infrastructure
Energy & power transmission
Telecoms & data ducting networks
Commercial & industrial basements
Mining & subterranean structures
Rail & railway infrastructure
Trusted by infrastructure and engineering companies
Tunneling GLT has delivered underground construction and specialist technical services for major infrastructure programmes across Europe, Latin America, and international markets. The following reflect the experience of engineering directors and project managers who have engaged our teams on complex underground construction contracts.
We required an underground construction crew with tunnel lining experience at short notice for a section of a transport infrastructure programme. Tunneling GLT mobilised an equipped team — drill operators, shotcrete technicians, and a tunnel supervisor — within a week of contract award. Works were executed on programme and to the specification required.
For a large mixed-use development, we required a single underground construction contractor capable of coordinating gas, water, and electrical infrastructure installation across the full site programme. Tunneling GLT delivered the complete below-ground package from initial ground investigation through to adoption submissions, significantly reducing our coordination risk.
A structural failure affecting buried infrastructure adjacent to a live construction corridor required immediate excavation, assessment, and remediation. Tunneling GLT mobilised within 24 hours, managed safe excavation around multiple conflicting services, and completed permanent reinstatement within the regulatory timescale permitted by the authority.
Ready to discuss your underground construction project?
Tunneling GLT provides specialist underground construction services for civil infrastructure projects of all scales and complexities. Whether your project requires a conventional tunnel drive, a trenchless crossing beneath critical infrastructure, or an integrated below-ground utility package, our engineering team is available to assess your requirements and deliver a technically grounded and commercially transparent proposal.
Some related services
Technical and commercial answers to the most common questions about underground construction, contracting methods, and project planning.
What is underground construction?
Underground construction refers to the discipline of civil engineering concerned with the planning, design, and execution of works carried out below the ground surface. This encompasses the excavation and permanent lining of tunnels for transport, utility, and infrastructure use; the installation of below-ground utility networks including water, gas, electricity, and telecoms; the construction of underground civil structures such as shafts, basements, and subterranean chambers; and the associated ground investigation, temporary works, and surface reinstatement activities required to safely complete subterranean works.
Underground construction is distinguished from surface civil engineering by the specialist geotechnical knowledge, confined space working procedures, ground support systems, and structural design approaches required to manage the unique risks and constraints of working below the existing ground level.
What types of underground construction does Tunneling GLT undertake?
Tunneling GLT’s underground construction capability covers the following principal categories:
Tunnel excavation and lining: Drill-and-blast and mechanised excavation of hard rock and soft ground tunnels, including primary support installation, waterproofing, and permanent lining construction.
Trenchless construction: Horizontal directional drilling (HDD), pipe jacking, and microtunneling for the installation of utility crossings, conduits, and small-diameter tunnels beneath roads, railways, and waterways without open excavation.
Underground utility construction: Open-cut and trenchless installation of water mains, gas pipelines, electrical cable systems, and telecoms ducting, managed from initial ground investigation to final reinstatement.
Underground civil structures: Construction of shafts, underground chambers, station boxes, and subterranean basements requiring specialist temporary works design and permanent structural installation.
Multi-utility and infrastructure packages: Coordinated below-ground infrastructure installation across multiple utility disciplines for development sites, highway corridors, and major regeneration programmes.
Each project is assessed individually to define the appropriate construction methodology, geotechnical requirements, and programme structure.
What is the difference between open-cut excavation and trenchless underground construction?
Open-cut excavation involves the removal of surface material — carriageway, footway, or ground cover — to expose the required depth for underground construction. It is the most common and cost-effective method for utility installation and shallow underground works where surface disruption is acceptable and ground conditions permit stable trench formation.
Trenchless underground construction methods — including horizontal directional drilling (HDD), pipe jacking, and microtunneling — install infrastructure beneath the surface without open excavation. These methods are required when underground construction must cross beneath roads, railways, waterways, or in environments where surface disruption is impractical, prohibited, or commercially unacceptable due to traffic management and reinstatement costs.
Trenchless methods carry a higher unit cost per metre of underground installation but eliminate the significant ancillary costs and programme impacts associated with carriageway closure, traffic management, and full-depth reinstatement. The appropriate method for any underground construction project depends on surface constraints, utility type, ground conditions, diameter of installation, and overall programme requirements.
What ground conditions are suitable for underground construction?
Underground construction is technically feasible across a wide range of ground conditions, though the appropriate excavation method, ground support system, and structural design approach will vary significantly based on the geotechnical profile of each project.
In stable cohesive soils — clays, silts, and firm ground — open-cut excavation and conventional tunnel drives proceed efficiently with standard trench support or sprayed concrete lining. In granular or water-bearing ground — sands, gravels, and made ground with elevated groundwater levels — dewatering systems, sheet piling, or compressed air working may be required to maintain excavation stability.
In rock conditions, underground construction typically employs drill-and-blast excavation, mechanical rock cutting, or tunnel boring machines (TBMs) depending on the rock mass characteristics and tunnel diameter. In mixed-face conditions — where rock and soil are encountered simultaneously — construction methodology must be adapted to manage both materials safely.
Tunneling GLT conducts geotechnical assessments prior to project mobilisation and, where required, commissions site investigation works to confirm appropriate underground construction methods and equipment selection for the specific ground profile of each project.
What safety requirements apply to underground construction?
Underground construction is classified as a high-risk construction activity and is subject to rigorous safety management requirements across all phases of the project lifecycle. Key safety obligations include:
Confined space management: All underground workings — tunnels, shafts, and below-ground excavations — are classified as confined spaces and require specific entry procedures, atmospheric monitoring, rescue plans, and operative competency certification.
Ground support and structural safety: Temporary and permanent ground support systems must be designed by qualified engineers and installed in accordance with the excavation sequence and geotechnical conditions. Face stability and support installation must be managed continuously during excavation.
Safe digging and utility avoidance: Prior to any underground excavation, utility records must be obtained, physical detection surveys conducted, and hand or vacuum excavation used within defined proximity zones around known buried services.
Fire and emergency procedures: Underground construction environments require specific fire suppression, emergency communication, and evacuation procedures that account for the confined nature of the working environment.
Health and safety management system: Underground construction contractors must operate under a documented safety management system compliant with applicable national and international standards (e.g., ISO 45001 or equivalent).
Tunneling GLT applies a comprehensive safety management framework to all underground construction projects. Our project safety documentation is available for review as part of the pre-contract process.
How is underground construction planned and coordinated with infrastructure owners?
Underground construction projects require a structured coordination process with infrastructure owners, utility network operators, highway authorities, and regulatory bodies prior to and during construction. The key coordination stages typically include:
Initial ground investigation: Commissioning of geotechnical and utility investigation works to establish the ground profile and existing buried service positions within the project area.
Statutory notification: Filing of formal notifications with relevant asset owners and authorities within the statutory timeframes required by applicable regulations.
Utility records and detection: Obtaining utility network records from all relevant asset owners and conducting on-site cable avoidance tool (CAT), ground-penetrating radar (GPR), or vacuum excavation surveys to verify service positions.
Permit and approval processes: Obtaining excavation permits, highway licences, and any environmental consents required for the proposed underground construction works.
Ongoing asset owner liaison: Maintaining active communication with utility and infrastructure asset owners throughout the underground construction programme, particularly during excavation in proximity to recorded services or sensitive structures.
Tunneling GLT manages the full coordination process on behalf of our clients, liaising directly with all relevant authorities and asset owners from project initiation through to reinstatement sign-off.
What is a tunnel boring machine (TBM) and when is it used in underground construction?
A tunnel boring machine (TBM) is a mechanised underground construction system that excavates a full circular tunnel profile simultaneously with the installation of the primary tunnel lining. TBMs are classified by their excavation and face support mechanism: open-face TBMs for stable ground conditions, earth pressure balance (EPB) machines for soft or water-bearing ground, and slurry TBMs for highly permeable or unstable ground below the water table.
TBMs are used in underground construction when the tunnel drive is of sufficient length to justify the capital cost of machine procurement or rental, typically from several hundred metres upward. They are the preferred method for urban tunnelling beneath built environments where surface subsidence must be minimised, and for large-diameter transport tunnels where conventional drill-and-blast methods would be impractical.
The selection of a TBM for an underground construction project requires specialist geotechnical assessment, alignment engineering, and logistical planning for TBM launch, retrieval, and segment supply chain management.
How is underground construction priced?
The cost of underground construction varies significantly based on project-specific factors including:
Excavation method: Trenchless underground construction (HDD, pipe jacking, TBM) carries higher unit costs per metre than open-cut excavation but avoids substantial ancillary costs including carriageway reinstatement, traffic management, and surface disruption.
Ground conditions: Poor, variable, or water-bearing ground requiring dewatering, specialist ground treatment, or enhanced support systems will increase the cost of underground construction compared with stable, predictable ground profiles.
Tunnel diameter and length: Larger-diameter tunnels require more substantial excavation, support, and lining systems. Longer drives typically reduce the unit cost per metre due to plant amortisation but require greater upfront mobilisation investment.
Lining specification: Permanent tunnel lining requirements — whether sprayed concrete, precast concrete segments, or steel — significantly affect material and installation cost.
Programme requirements: Accelerated or shift-working programmes to compress construction duration carry a labour premium.
Coordination complexity: Projects requiring extensive utility diversion, multi-agency coordination, or complex traffic management arrangements incur a higher programme management cost.
Tunneling GLT provides project-specific cost assessments following initial technical review of available ground investigation data, drawings, and project scope. Contact our project team with your requirements for a commercially transparent and technically grounded proposal.
What qualifications and certifications should an underground construction contractor hold?
The certifications and accreditations required of an underground construction contractor vary by jurisdiction, project type, and the specific underground construction scope involved. Common requirements include:
Occupational health and safety: ISO 45001 or equivalent occupational health and safety management system certification, with specific safe systems of work for confined space entry and underground working.
Tunnel and underground construction competency: Operative and supervisory qualifications specific to tunnel excavation, ground support installation, and underground utility construction — including confined space working certification.
Gas safe working: Gas Safe registration and operative qualifications for any underground construction involving gas distribution infrastructure.
Electrical safe systems of work: Authorised and competent person designations for underground construction works on or adjacent to electrical networks.
Streetworks compliance: Operative and supervisory streetworks accreditation (e.g., NRSWA in the UK or equivalent in other jurisdictions) for any underground utility works within public highways.
Environmental management: ISO 14001 certification for projects with environmental management plan requirements, including groundwater protection and contaminated land management.
Tunneling GLT operates under a comprehensive quality, health, safety, and environmental management framework. Relevant accreditation and certification documentation is provided to clients as part of the pre-qualification process.