Geotechnical, Underground Structures and Tunneling

Engineering What Happens Below the Surface

Some of infrastructure’s most complex challenges begin underground. Tunnels, foundations and underground structures must respond to conditions that cannot always be seen or fully understood at the outset, while supporting critical transportation, water, utility, energy and development infrastructure above and below them.

STV approaches these challenges by connecting geotechnical understanding with structural design, tunneling and constructability. Our experience spans new infrastructure as well as the rehabilitation and modernization of existing assets, including major rail tunnels, transit connections and underground utility infrastructure. This perspective allows our teams to understand not only the ground and the structure, but also how underground work affects the larger system it serves.

Our Capabilities in Geotechnical, Underground Structures & Tunneling

STV provides integrated expertise from initial investigation and feasibility through design, construction and rehabilitation:

• Geotechnical Engineering and Subsurface Investigation: Characterizing soil, rock and groundwater conditions and translating that information into practical design strategies for foundations, slopes, earth retention, ground improvement and other infrastructure.
• Tunneling and Underground Structures: Designing new and rehabilitated tunnels, underground stations, pedestrian connections and other below-grade structures using methods suited to site conditions, project requirements and surrounding infrastructure.
• Excavation and Ground Support: Developing solutions for excavation support, underpinning, dewatering, retaining systems and temporary and permanent works that help manage movement and protect adjacent assets.
• Tunnel Rehabilitation and Asset Renewal: Evaluating existing conditions and developing rehabilitation strategies that extend service life, improve performance and allow critical infrastructure to remain resilient and reliable.
• Trenchless and Specialized Underground Solutions: Applying tunnel boring machines, sequential excavation, drill-and-blast, cut-and-cover and trenchless methods where appropriate to advance infrastructure through constrained environments while limiting surface impacts.
• Instrumentation, Monitoring and Modeling: Using analytical tools, numerical modeling and field monitoring to understand ground and structural behavior and support informed decisions during design and construction.

What Sets STV Apart

• The Ground and Structure Considered Together: Underground projects require more than isolated geotechnical or structural solutions. Our teams connect subsurface conditions, structural behavior, construction approach and long-term performance so that decisions in one discipline strengthen the project as a whole.
• Experience Where Infrastructure is Most Constrained: Much of STV’s tunneling work supports transportation and infrastructure in complex, active environments. That includes designing underground connections at major multimodal hubs and contributing to extensive tunnel systems beneath dense urban areas, where construction must coexist with buildings, utilities and operating transportation networks.
• New Infrastructure and the Systems we Already Depend On: The challenge is increasingly not only building new underground infrastructure, but renewing aging assets without disrupting the services communities rely on. STV brings design and rehabilitation experience that helps owners extend asset life, improve resilience and modernize critical systems.
• Methods Driven by Conditions, not Prescribed Solutions: Rock, soil, groundwater, neighboring structures, operations and access all affect how underground infrastructure should be built. We bring experience across conventional and mechanized tunneling, excavation support, ground improvement and trenchless approaches to develop solutions around each project’s specific conditions.
• Expertise Connected Across Markets: Geotechnical and underground engineering supports far more than tunnels. Our specialists collaborate across rail and transit, highways and bridges, water, buildings, utilities, ports and energy, bringing lessons from one type of infrastructure to challenges in another.
• Local Understanding Backed by Broader Expertise: Subsurface conditions are inherently local, while the engineering challenges they create benefit from wider experience. STV combines knowledge of regional conditions with a nationwide technical practice, giving clients access to specialized expertise while keeping solutions grounded in the realities of the site and community.