Posted by M. Melih Demirkan, Peter Laskaris / Wang Technology • 09 Nov 2025
Instrumentation and monitoring (I&M) in tunnel construction have often been underappreciated within the broader construction processes. I&M refers to the systematic deployment of advanced sensors, measurement tools, and data management platforms to monitor deformation, stress, pressure, vibration, and other critical parameters during construction.
With the advancement of measurement techniques and especially data communication and data management tools, monitoring has grown to provide a strong value—value that the tunnel industry is increasingly recognizing and implementing. Despite over 30 years of experience working on complex tunnel projects with major engineering and construction firms, we can report that there is still untapped potential that monitoring can offer. Building trust in monitoring data remains a challenge.
The benefits of I&M are far-reaching. I&M serves as an essential feedback mechanism, enabling stakeholders to validate design models, assess structural behavior, and make informed decisions to enhance safety and performance.
I&M enhance risk management and ensure the safety of construction personnel and surrounding communities. By detecting potential issues early, monitoring minimizes costly delays and helps maintain project timelines. Furthermore, these systems contribute to data-driven decision-making, improve stakeholder confidence, and offer long-term value by facilitating maintenance and operational planning for completed structures.
Due to obvious and long waiting reasons like aging infrastructure and environmental concerns, the construction of tunnels for metro systems, combined sewage overflow (CSO) projects, railways, and water conveyance/flood protection have been booming across North America.
Many of these projects rely on TBMs and involve large-diameter tunnels sometimes exceeding 30 ft and mining in populated areas. Ground disturbance due to construction activities constitutes large but manageable risks.
With such massive undertakings, I&M plays a critical role in understanding the impact of support of excavation (SOE) and ground subsidence within the zone of influence. Many projects have successfully integrated monitoring systems to ensure safety and performance, demonstrating the industry’s ability to leverage these technologies effectively. Yet, despite its critical role, monitoring sometimes seems like an afterthought or, worse, an expense to be minimized.
Modern monitoring solutions include robotic total stations, conventional structural and geotechnical instruments for pressure, strain, and deformation measurements (piezometers, inclinometers, strain gauges, extensometers, etc.), terrestrial laser scanning, vibration sensors, wireless sensor networks, and even fiber optic sensing (a less common application) in tunnel monitoring.
Our experience has shown that a well-defined monitoring scope typically accounts for around 1–2% of the overall project budget. As Red Book author John Dunnicliff aptly stated, “The lowest cost of an instrument should never dominate the selection.”
The importance of qualified instrumentation providers cannot be overstated, as selecting the right partner ensures the monitoring program’s success. Using an experienced monitoring provider is more critical than which instrument type or brand is selected.
The following are some challenges that a typical monitoring scope in a tunnel project faces, along with select solutions.
Large, publicly funded projects place monitoring design and oversight under the control of owners, regulators, and the owner’s engineers. While some contractors may view monitoring as a compliance requirement, many have embraced it as a key component of risk management.
Instrumentation must be integrated in tandem with the construction sequence, requiring instrumentation specialists to be part of the project team who understand construction stages and structural components.
Solution: Implementation of the I&M program is a critical path activity and must be coordinated with traditional construction milestones. Early collaboration, regular workshops, and assigning a monitoring coordinator help align expectations and ensure successful execution.
Instrumentation specifications prepared by consultants are often treated as the project “bible” but are frequently based on outdated references. This can hinder successful implementation by failing to account for project-specific needs and modern technology.
Solution: Specifications must be tailored to each project and updated to reflect current technology. Experienced instrumentation specialists should be engaged early to review and refine requirements.
Once a project is awarded, approving newer technology can be uncertain and time-consuming, forcing providers to deploy older, less reliable instruments just to meet schedules—despite newer tools offering better accuracy, reliability, and lower maintenance costs.
Baseline monitoring is critical to understanding structural behavior. Short baseline periods can result in incomplete data and unreliable trend analysis, particularly for long-duration projects.
Solution: Extend baseline monitoring whenever possible and collect meaningful long-term data early. Early investment in quality baseline data pays dividends later.
Manual readings are common but introduce delays and human error. Automated systems provide higher accuracy, greater data volume, and near-real-time availability.
Solution: Establish automated measurements as the standard, supported by manual readings for redundancy. Modern wireless systems offer long battery life and reduced maintenance.
Data redundancy ensures reliability and confidence by allowing cross-verification of measurements. Complementary instruments help confirm or refute anomalies and improve decision-making.
Solution: Implement complementary monitoring methods as standard practice. Redundancy strengthens system resilience and ensures decisions are based on verified, high-quality data.
Modern data platforms enable real-time visualization, sharing, and analysis but are often underutilized.
Solution: Make data management platforms central to monitoring strategies. Train stakeholders and customize dashboards to maximize collaboration and risk mitigation.
Based on our long experience, we recommend that I&M be recognized as a critical component of risk management and project execution.
By embracing advanced monitoring technologies, fostering collaboration, and prioritizing data quality, the tunnel industry can enhance safety, efficiency, and innovation.
Many projects have already demonstrated success through robust monitoring systems. Building on these best practices will unlock the full potential of instrumentation and monitoring to safeguard projects, investments, and communities.
.jpg)
-(M).jpg)
.jpg)
.jpg)
