TUN/Specific/TBT-TUN-010

TBM (Tunnel Boring Machine) Safety

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TBM (Tunnel Boring Machine) Safety

Toolbox Talk Record

Ref: TBT-TUN-010  |  Issue: 1  |  Date: March 2026
PresenterProject
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What?

  • 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.

Why?

Confined environmentWorkers inside a TBM are in a confined space with limited escape — any incident becomes a major emergency rapidly.
Crushing hazardsThe cutterhead, erector, and conveyors create multiple entrapment points that can cause fatal crushing injuries.
Fire riskHydraulic oil, electrical systems, and grease in a confined tunnel make TBM fires extremely dangerous and difficult to fight.
Do Don't
  • Complete machine-specific TBM induction before entering the tunnel
  • Wear hearing protection at all times when inside or near the TBM
  • Know the emergency evacuation route and location of refuge chambers
  • Follow lockout procedures before any maintenance on TBM components
  • Check ventilation systems are operating before entering the tunnel heading
  • Use the communication systems provided to stay in contact with the surface
  • Report any unusual ground behaviour, water ingress, or machine vibration
  • Carry a personal gas monitor and self-rescuer at all times underground
  • Keep escape routes and walkways clear of obstructions and debris
  • Attend daily briefings covering TBM progress, hazards, and planned activities
  • 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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