Key Responsibilities and Required Skills for Underground Tunnel Technician

🎯 Role Definition

The Underground Tunnel Technician is a skilled field technician responsible for the safe operation, inspection, maintenance, repair, and monitoring of subterranean infrastructure including rail, transit, utility and stormwater tunnels. This role requires hands-on expertise with tunnel construction and maintenance trades (mechanical, electrical, concrete, waterproofing), strict adherence to confined-space and tunnel-specific safety protocols, operational competence with tunneling equipment (TBMs, conveyors, pumps), and the ability to document conditions and collaborate directly with engineers and project managers to support reliability, asset longevity and emergency response.

📈 Career Progression

Typical Career Path

Entry Point From:

Underground Maintenance Worker / Utility Laborer
Rail/Transit Track Technician
Construction Technician or Apprentice (mechanical/electrical/concrete)

Advancement To:

Senior Tunnel Technician / Lead Tunnel Technician
Tunnel Maintenance Supervisor / Site Supervisor
Tunnel Systems Engineer / Field Engineer

Lateral Moves:

TBM Operator
Underground Safety Officer / Confined Space Coordinator
Tunnel Instrumentation & Monitoring Technician

Core Responsibilities

Primary Functions

Perform routine and preventative inspections of tunnel structures, linings, segmental rings and joints, recording detailed condition assessments and identifying deterioration, water ingress, spalling, cracks, or voids for timely remediation and lifecycle planning.
Execute scheduled and emergency maintenance on tunnel mechanical and electrical systems, including ventilation blowers, jet fans, dewatering pumps, hoists, lighting, and power distribution, ensuring systems meet operational and safety standards.
Install, maintain and repair ground support systems such as rock bolts, cable anchors, steel ribs, mesh and shotcrete applications to stabilize excavations and maintain structural integrity under geotechnical guidance.
Operate and support tunneling equipment and site machinery including tunnel boring machines (TBMs), roadheaders, concrete sprayers, shotcrete trucks, grout pumps and conveyor systems in accordance with OEM guidelines and project procedures.
Conduct confined-space entry tasks safely by following entry permits, atmospheric testing with multi-gas detectors, continuous monitoring, use of rescue harnesses and breathing apparatus where required; coordinate entry/exit with a trained attendant and rescue plan.
Perform grout injection and chemical sealing operations to control water ingress, void filling and backfill stabilization; document volumes, pressures and materials used for quality control and design verification.
Execute concrete repair, resurfacing and sealing works on tunnel invert, benches and sidewalls using epoxy injections, polymer overlays, and traditional cast-in-place methods while ensuring proper curing and QA/QC.
Install, test and maintain tunnel instrumentation and monitoring systems (inclinometers, extensometers, piezometers, settlement plates, strain gauges), collect and log data, and escalate anomalous readings to engineering teams promptly.
Perform cable pulling, splicing and conduit installation for power, communications and SCADA systems following electrical drawings, ensuring appropriate bundling, labeling and segregation from water-bearing elements.
Perform welding, cutting, and mechanical fabrication tasks for repair or installation of brackets, rails, anchor points, and service platforms while complying with welding codes and confined-space welding safety rules.
Operate and maintain dewatering systems, pumps, sumps and associated piping to manage groundwater and stormwater inflows, including regular pump testing, impeller checks and discharge monitoring.
Conduct ventilation system balancing and smoke control testing, measure airflows, troubleshoot blocked ducts or damaged fans, and implement temporary ventilation solutions during maintenance or emergency scenarios.
Carry out track and rail works in rail tunnels: rail grinding, fastening replacement, tie/sleeper repair, ballast cleaning and track geometry inspections to preserve safe transit operations and minimize downtime.
Implement surface and subsurface leak detection protocols, trace sources of seepage and coordinate with waterproofing specialists to apply membranes, injections or joint repair systems as required.
Maintain daily logs, maintenance records, inspection reports, and digital asset management entries; ensure accurate, time-stamped documentation for compliance, warranty and handover reporting.
Respond to tunnel emergencies including fires, flooding, derailments or hazardous material incidents by executing established emergency response plans, coordinating with first responders, and performing initial containment or rescue support as trained.
Coordinate and communicate work activities with project management, engineers, utility owners and traffic/operations control centers to ensure safe access windows, minimal disruption and proper clearances for lane or rail closures.
Follow environmental controls and contamination protocols: implement dust suppression, waste containment, dewatering discharge permits, and handle identified hazardous materials (asbestos, hydrocarbons) only with qualified personnel and documented procedures.
Support quality assurance and testing activities such as concrete sampling, NDT (ultrasonic, half-cell potential, thickness gauges), and acceptance checks for repairs or new installations, and facilitate third-party inspections.
Supervise and mentor junior technicians or subcontracted crews on safe tunneling practices, tool use, and company-standard procedures while maintaining accountability for assigned work packages.
Prepare and maintain tooling, spare parts, PPE, and consumables inventories; coordinate procurement requests and plan spares for critical tunnel assets to reduce reactive downtime.
Implement continuous improvement recommendations derived from field observations, root cause analyses and post-work debriefs to enhance work methods, reduce risk and improve asset reliability.

Secondary Functions

Act as a technical resource during planning and pre-construction meetings to provide practical input on access, logistics, ventilation, and phasing for tunnel works.
Assist in the preparation and execution of permit-to-work packages, work method statements, lifting plans, and confined-space entries ensuring regulatory compliance and organizational approval.
Participate in scheduled safety audits, toolbox talks and competency assessments; contribute corrective action items and verify closure of identified safety gaps.
Support data collection initiatives for BIM/asset management systems by uploading geotagged photos, inspection notes, and as-built deviations to the project database.
Coordinate and support contractor mobilization, supervise subcontractor activities on-site and verify completed works against scope and contractual deliverables.
Provide field-level troubleshooting and diagnostics for SCADA alarms, instrumentation anomalies and mechanical breakdowns until specialists arrive; apply temporary mitigations when safe and appropriate.
Assist with community and stakeholder liaison activities when tunnel work impacts surface operations, including responding to inquiries, documenting disturbances and coordinating mitigation measures.
Contribute to after-action reviews and incident investigations by supplying factual field observations, timelines and equipment condition data.
Support training programs by demonstrating practical skills in confined-space entry, gas detection, tool operation and emergency response exercises.
Maintain awareness of new materials, tools and construction techniques and recommend pilot trials when they present clear safety or efficiency benefits.

Required Skills & Competencies

Hard Skills (Technical)

Confined Space Entry and Rescue certified (permit-required confined space procedures and attendant/rescue practice).
Proficient with tunnel machinery and equipment: TBM support systems, shotcrete rigs, grout pumps, dewatering pumps and conveyor systems.
Strong knowledge of ground support installation: rock bolts, cable anchors, steel ribs, mesh and shotcrete application techniques.
Experience with instrumentation and monitoring devices: installation, calibration and data interpretation for inclinometers, piezometers, extensometers and settlement plates.
Competent in mechanical trades including welding (MIG/TIG/Stick), pipefitting, fabrication and basic structural repair.
Electrical and low-voltage skills for cable pulling, terminations, motor starters, fan controls and troubleshooting protective devices.
Skilled in concrete repair methods, surface preparation, epoxy/polymer injection and non-destructive testing (NDT) inspection techniques.
Proficient with gas detection and atmospheric testing equipment (multi-gas monitors) and atmospheric control strategies.
Experience operating lifting equipment and rigging practices; certified rigging and slinging knowledge for safe material handling in tunnels.
Ability to read and interpret engineering drawings, tunnel alignment plans, SOWs and maintenance manuals; familiarity with surveying tools (total station, laser level) is a plus.
Proficient with mobile data capture, CMMS/asset management systems, and digital reporting tools (photographic documentation, GPS/geotagging).
Knowledge of ventilation systems, smoke control strategies and experience performing airflow measurements and fan balancing.

Soft Skills

Strong commitment to safety culture and the ability to enforce safety rules while influencing crew behavior.
Clear verbal and written communication skills for reporting conditions, writing detailed inspection notes, and coordinating with multidisciplinary teams.
Problem-solving orientation with practical troubleshooting skills and the ability to apply temporary mitigations under pressure.
High attention to detail for inspections, measurements and adherence to method statements and QA/QC procedures.
Teamwork and leadership abilities to mentor junior staff, lead small crews and liaise with contractors and stakeholders.
Adaptability and resilience to work in confined, dark, wet or noisy underground environments on variable shifts.
Time management and planning skills to prioritize maintenance tasks during limited track or tunnel access windows.
Analytical mindset for interpreting monitoring data and escalating trends that may affect structural safety or operations.
Customer/service orientation when coordinating with operations centers, rail/utility owners and public stakeholders.
Initiative to identify continuous improvement opportunities and implement field-level efficiencies.

Education & Experience

Educational Background

Minimum Education:

High school diploma or equivalent (required)

Preferred Education:

Associate degree or diploma in Civil Engineering Technology, Construction Technology, Mechanical or Electrical Trades, Mining Technology, or related technical field
Trade certification or apprenticeship completion in welding, mechanical or electrical disciplines

Relevant Fields of Study:

Civil Engineering Technology
Construction Management/Technology
Mechanical or Electrical Trade Apprenticeships
Mining or Geotechnical Technology

Experience Requirements

Typical Experience Range: 2–8 years of hands-on experience in underground construction, tunnel maintenance, transit systems, utilities or mining environments.

Preferred:

4+ years of direct tunnel experience (rail or utility tunnels preferred)
Demonstrated experience with confined-space entry, ground support installation, shotcrete and grout operations
Prior exposure to TBM support, instrumentation monitoring, or rail/track maintenance strongly preferred
Relevant certifications: Confined Space, First Aid/CPR, OSHA 30 (or national equivalent), H2S awareness or refresher as applicable; rigging/crane operator certifications as required by site