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Control measure

Apply specialist controls and intervention limits

Control measure knowledge

The notification of any tunnel or underground structure project should be the starting point for engagement with the client, principal contractor and responders. This will enable the most hazardous phase of the project to be risk-assessed. The outcome of the risk assessment will inform the development of any special procedures, restrictions or limitations to be applied well before the construction phase commences. Risk assessment outcomes and plans must be confirmed in writing.

Special controls and procedures agreed must be recorded in the emergency plan and communicated to all partners so they can be implemented quickly and without confusion. Special controls, restrictions or limitations will need to be applied to dead end conditions. These can be created when a tunnel boring machine (TBM) commences boring and the services required to support a fire and rescue service intervention cannot be established for a period of time. In a fire situation, this would mean that the fire and rescue service could only make a limited intervention, as a charged line of delivery hose cannot be dragged for long distances.

A normal control measure applied during these circumstances is for the tunnel boring machine (TBM) to be provided with a water mist system to protect walkways, and a rear water curtain to protect the TBM crew who would remain on-board.

The hand digging of cross passages and the need to enter the cutting head of the tunnel boring machine both involve working in confined spaces. Such conditions will require the contractor to have special rescue teams available on scene when work is being carried out, as this responsibility cannot be discharged to the fire and rescue service. Although some fire and rescue service personnel are trained and equipped to work in confined spaces, technical rescue teams are not normally mobilised as part of the fire and rescue service first attendance and there will be a delay in intervention.

As the tunnel or underground structure reaches completion, the hazard and risk significantly reduces because the 'as built' environment will include all the design safety features that support an intervention.

Strategic actions

Fire and rescue services should:
  • Conduct regular site visits to ensure complete awareness of the site access point and the access control system

Tactical actions

Incident commanders should:
  • Establish and communicate limits of operation based on identified risks and available resources