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Somewhere beneath Chennai, a machine the length of several buses is grinding forward through soil and rock at a pace measured in metres per day, lining the tunnel behind itself as it goes. The people working on it are doing some of the most specialised construction work in India, on a schedule that never stops, in an environment that punishes carelessness immediately.
Tunnelling is the most technically demanding part of a metro construction project and the least understood by people looking for work on one. This article explains what the work involves, who does it, what skills it needs, and what to check before joining a tunnelling contractor.
It is general information about construction work in India. It is not a recruitment notice and is not issued by any metro corporation or contracting company.
How a metro tunnel is actually built
Urban metro tunnels in India are generally driven with tunnel boring machines, chosen because they allow tunnelling beneath a dense city with limited disturbance at the surface.
The sequence begins with a launching shaft: a deep excavation, often at a station site, from which the machine starts. The machine is assembled in the shaft, sometimes over weeks, and then begins its drive.
As it advances, a cutterhead at the front excavates the ground. Excavated material — the muck — is removed continuously through the machine and out of the tunnel. Immediately behind, precast concrete segments are erected into rings that form the permanent tunnel lining, and the annular gap behind them is grouted.
The machine drives to a reception shaft, where it is either dismantled or prepared for a further drive. Once the tunnel is complete, a second phase of work fits it out: track, traction, cables, walkways, drainage, ventilation and fire systems.
Alongside all of this runs a segment casting yard, often at a separate location, producing the lining segments to tight tolerances — itself a substantial industrial operation employing concrete, formwork and quality personnel.
The roles on a tunnelling operation
TBM operator and crew. Operating the machine, monitoring pressures and parameters, and responding to changing ground. Highly skilled, usually built up from years in tunnelling rather than entered directly.
Segment erector operators. Placing the lining segments accurately, ring after ring, in confined space.
Grouting crew. Filling the annular gap behind the lining, which is essential to controlling surface settlement above.
Muck handling and logistics. Moving excavated material out and materials in, through a tunnel that has one way in and out. Continuous, tightly scheduled work.
Mechanical and electrical fitters. Maintaining the machine, which is a factory in its own right with hydraulics, conveyors, electrical systems and controls. Downtime is expensive, so maintenance crews are central rather than peripheral.
Surveyors. Keeping the drive on alignment. A tunnel that deviates is a very expensive problem, which makes survey work unusually consequential.
Ventilation, safety and rescue personnel. Managing the atmosphere, monitoring, and standing ready for emergency response.
Shaft and surface crews. Craneage, materials, segment handling and site logistics.
Instrumentation and monitoring teams. Watching for ground movement and settlement of buildings above the drive, which in a dense city is a continuous responsibility.
Who employs these people
Not the metro corporation. Tunnelling packages are executed by construction contractors, frequently large infrastructure companies and often as joint ventures, with subcontractors and labour contractors beneath them.
Specialist elements bring in further employers: the machine manufacturer own technicians for certain work, specialist grouting and monitoring firms, and survey consultancies.
The first question at any tunnelling job interview is therefore the same as on any construction site: what is the registered name of the company that will employ me? Get it, and expect an appointment letter on that company letterhead.
Why tunnelling pays better, and what it costs
Skilled tunnelling work generally pays above equivalent surface construction work, for reasons that are worth understanding rather than simply welcoming.
The skills are scarce. Relatively few people in India have real TBM experience, and projects compete for them.
The work is continuous. A drive does not stop for nights, weekends or festivals, because stopping a machine mid-drive causes problems. That means round-the-clock shift working for the duration.
The environment is demanding. Confined, hot, humid, noisy, with limited natural light and a long walk or ride to the face.
And the responsibility is high. The consequences of error include damage to buildings above and risk to the crew below.
So the premium is real and it is paid for something. Anyone considering this work should weigh the pattern honestly: it is well-paid, intense, project-bound work that will take over your schedule for as long as the drive lasts.
Safety underground
Tunnelling safety is a serious discipline and this section is not decoration.
The principal hazards are atmosphere — oxygen deficiency, harmful gases, and the ventilation systems that manage them; fire, which in a tunnel is exceptionally dangerous because escape routes are limited and smoke fills the space; confined space and access, including the arrangements for getting people out in an emergency; ground behaviour, including instability and water ingress; machinery, with heavy moving equipment in confined space; and logistics traffic within the tunnel.
Controls follow directly: permit systems for entry and for high-risk work, continuous atmospheric monitoring, forced ventilation, strict accounting of who is underground at any moment, defined escape and rescue arrangements, fire precautions and refuge provisions, and rigorous isolation procedures for work on machinery.
The behaviours expected of you are absolute. Never go underground without being accounted for. Never enter an area not cleared for entry. Never work on machinery you have not personally confirmed is isolated. Respond to an alarm by leaving, not by investigating. And report anything unusual — a smell, a sound, water where there was none — immediately, because underground, small changes are information.
Induction training for tunnelling is longer and more detailed than for surface work. That is proportionate. Take it seriously.
How people get into tunnelling
Very few people enter tunnelling directly at a skilled level. The common routes are these.
From a trade. Fitters, electricians, welders and plant maintenance technicians are needed on every tunnelling operation, and a trade holder with solid experience can move into tunnel work and then progressively into more specialised roles.
From general construction. Workers who prove reliable on surface packages are frequently taken underground as opportunities arise, and learn the specialised work in place.
From surveying. Survey work on a tunnelling project is a distinct and well-regarded route requiring specific technical training.
From engineering. Diploma and degree holders enter as site engineers and progress into tunnelling engineering and management.
The pattern to notice is that tunnelling experience is cumulative and portable. India has a great deal of tunnelling ahead of it — metros in multiple cities, rail projects, hydropower and water schemes — and a worker with a genuine record of tunnel drives is employable across all of them, including internationally.
Which makes documentation unusually valuable here. Keep a record of every project, every drive, every machine type, every role and every certification, with dates and an experience letter from each employer. That record is what converts years of hard work into a career rather than a series of jobs.
What to check before you join
Everything that applies to construction employment generally applies here with added force, because the work is more hazardous and the sites are more remote from ordinary oversight.
Get the employer registered name and an appointment letter. Confirm the wage and how overtime and shift premiums are calculated. Insist on bank payment with a payslip rather than cash. Confirm provident fund and insurance are deducted and deposited under your own numbers, and keep one Universal Account Number across employers. Ask what protective equipment is provided, what the induction training covers, and what accommodation and transport arrangements exist.
And the absolute rule, which matters most in exactly this kind of employment: nobody should be charging you anything — no commission to the person arranging the work, no deposit for equipment, no gate pass fee, no travel advance to be worked off. Payment flowing from worker to employer or agent is the definitive marker of exploitation.
Frequently asked questions
Do I need experience to start? For skilled tunnelling roles, generally yes. Entry is usually through a trade or through general construction on the same project.
Is it safe? Tunnelling is hazardous work made safe by strict systems. On a well-run project with proper controls it is managed; the danger lies in shortcuts and in poorly run operations.
How long do drives last? Months, and a full package can run for years. Ask about the expected duration of the specific package you are joining.
Will I have to relocate? Frequently, since tunnelling projects are where they are. Many tunnelling workers move between cities and states across a career.
Is it worth learning? If you are willing to travel and work shifts, tunnelling is one of the more secure skilled construction specialisms in India for the next decade.
Safety, rights and skilling references
- Ministry of Labour and Employment — Construction labour law and state departments
- Shram Suvidha Portal — Registrations and compliance
- e-Shram — Registration for unorganised sector workers
- National Safety Council — Occupational safety resources
- EPFO member portal — Check contributions are deposited
- Chennai Metro Rail Limited — Project information and official notices
The summary
Tunnelling is scarce, well-paid, continuous, hazardous and portable work, employed by contractors rather than by the metro. Learn a trade, get underground, take the safety systems absolutely seriously, document every drive you work on — and never pay anyone to be hired.
Disclaimer: This article is general career information only. It is not an official recruitment notice and is not affiliated with, endorsed by or authorised by any metro rail corporation, government department or contractor. Salary ranges shown in tags and elsewhere are indicative of what is commonly advertised for such roles and are not a quoted or guaranteed figure. Actual pay varies by organisation, city, post, grade and whether the role is direct or through a contractor, and only a signed offer letter or an official appointment order is binding. Always apply through the official website of the metro corporation concerned or a recognised government portal. This is not legal, financial or employment advice.
