Hazard Knowledge

There are relatively few tunnels in the UK that are long enough to require a mechanical ventilation system. Ventilation is used to supply fresh air, remove fumes, gases and dust, regulate the temperature, and to assist with smoke control in the event of a fire.

Tunnels may quickly fill with poor quality air due to the ventilation system:

• Driving fumes or smoke to unaffected areas
• Assisting the development and spread of fire
• Being impacted due to the incident or operational activities
• Being isolated
• Having failed or not being commissioned

Maintaining effective ventilation will be a key consideration for the incident commander. For further information involving fires refer to Fires in buildings: Fires in tunnels