TUN/Specific/TBT-TUN-010

TBM (Tunnel Boring Machine) Safety

Tunnelling & Shafts › Specific › TBM (Tunnel Boring Machine) Safety

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Tunnel boring machines (TBMs) are large mechanised systems that excavate tunnels in rock or soft ground.
TBMs create confined working environments with limited escape routes and complex ventilation needs.
The cutterhead, screw conveyor, and segment erector have severe crushing and entanglement hazards.
Hyperbaric interventions may be required to inspect or change cutting tools under compressed air.
Noise levels inside a TBM routinely exceed 85 dB, requiring mandatory hearing protection.
Emergency evacuation from a TBM can involve travelling hundreds of metres through the tunnel.
Spoil removal systems including conveyors and muck trains create additional moving machinery hazards.
Ground conditions ahead of the TBM can change without warning, causing face collapse or water inflow.
Fire in a TBM is extremely dangerous due to confined space, oil systems, and limited escape options.
All TBM operatives must receive machine-specific training before working on or near the machine.

Confined environment	Workers inside a TBM are in a confined space with limited escape — any incident becomes a major emergency rapidly.
Crushing hazards	The cutterhead, erector, and conveyors create multiple entrapment points that can cause fatal crushing injuries.
Fire risk	Hydraulic oil, electrical systems, and grease in a confined tunnel make TBM fires extremely dangerous and difficult to fight.

Don't

DON'T enter the cutterhead area without full isolation and a permit to work
DON'T bypass safety interlocks on the segment erector or conveyor systems
DON'T work near the screw conveyor or muck train without isolation in place
DON'T ignore ventilation alarms — evacuate if directed to do so
DON'T store flammable materials inside the TBM or near hydraulic systems
DON'T block emergency escape routes with equipment, materials, or spoil
DON'T enter compressed air zones without medical clearance and training
DON'T remove hearing protection inside the TBM at any time during operation
DON'T attempt to clear blockages in the cutterhead while it is still rotating
DON'T underestimate the distance to the portal — evacuation takes significant time

See also: Tunnelling Safety Awareness | Emergency Evacuation From Tunnels

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