Tunnelling Safety Awareness

Tunnelling is a high-risk specialist activity combining confined space, ground stability, and heavy plant hazards.
Tunnel ventilation must provide adequate fresh air and remove dust, fumes, and potentially dangerous gases.
Emergency evacuation from tunnels is complex — escape routes, refuges, and communication systems must be in place.
Ground conditions can change rapidly during tunnelling, causing face collapse, water inrush, or gas release.
Fire in a tunnel is extremely dangerous due to limited escape routes and rapid smoke accumulation.
Compressed air working may be required in certain ground conditions and is subject to strict medical controls.
All tunnel workers must receive specific induction training covering the unique hazards of the tunnel environment.
Communication systems including hard-wired phones, radios, and tannoy must be maintained throughout the tunnel.
Tunnel boring machines and pipe jacking equipment require specialist training and strict operating procedures.
Gas monitoring must be continuous during tunnelling operations to detect methane, CO2, and oxygen depletion.

Extreme environment	Tunnels combine confined space, unstable ground, limited escape, and heavy plant into one of construction's most dangerous workplaces.
Fire and evacuation	A fire in a tunnel can be fatal within minutes — prevention, detection, and rehearsed evacuation are critical.
Atmospheric hazards	Ground gases and exhaust fumes can displace oxygen or create explosive atmospheres underground without warning.

Do

Don't

Complete the tunnel-specific induction before entering any underground working area.
Monitor gas levels continuously using calibrated instruments throughout the shift.
Know the emergency evacuation route, refuge locations, and communication procedures.
Ensure ventilation systems are operating correctly before and during all tunnel work.
Follow fire prevention procedures — no smoking and strict controls on combustible materials.
Use the communication system to report your location and status as required.
Wear all required PPE including self-rescuer breathing apparatus where specified.
Follow LOTO procedures for all tunnel plant including TBMs and conveyors.
Report any changes in ground conditions, water ingress, or unusual smells immediately.
Participate in emergency evacuation drills and know how to use self-rescue equipment.

DON'T enter the tunnel without completing the site-specific tunnel induction.
DON'T ignore gas monitor readings — evacuate immediately if alarms activate.
DON'T work underground without knowing the evacuation route and refuge locations.
DON'T enter the tunnel if ventilation systems are not confirmed as operational.
DON'T bring combustible materials, naked flames, or smoking materials underground.
DON'T work in the tunnel without maintaining contact via the communication system.
DON'T remove your self-rescuer or RPE from your person while underground.
DON'T approach tunnel plant or TBMs without following the agreed safe procedures.
DON'T dismiss changes in ground conditions — they can indicate imminent face collapse.
DON'T skip emergency drills — practised evacuations save lives in real incidents.

See also: Tunnel Ventilation Requirements | Emergency Evacuation From Tunnels

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