Building Management Systems

Tunnel vent and smoke control

  • Posted by Tony Barham

Smoke exhaust ventilation (SHEV) systems ensures that smoke is vented out of tunnels allowing escape for passengers/visitors and access for fire fighters.

The LB Foster systems used in projects like Crossrail has provided solutions that increase the escape time which is life saving and time critical. Its one of our mission critical solutions that our clients rely on us to deliver in these major projects.

When smoke is detected with state of the art detectors, vents & access ready systems will automatically start providing managed access. Our systems provide exhaust and venting provision, designed for the station location specifically.

Features, dependent on locations can be:

Events in the tunnel will require different ventilation responses. These events will have different priorities, and some may require conflicting actions or system configurations

Normal Mode

  • Provide sufficient air exchange with atmosphere throughout the tunnels.
  • reduce the effects of train-induced draughts so that airspeeds in public areas do not exceed 5 m/s.
  • provide cooling to ensure that tunnel temperatures do not exceed 35 ºC DB.

Abnormal Mode

  • When one or more trains are stationary the system shall provide cooling so that the air temperature does not exceed 40 ºC DB.

Incident Mode

  • The system shall maintain a smoke-free route for intervention and evacuation purposes
  • It shall extract the smoke to atmosphere through a vent shaft or expel it via a portal.
  • Move smoke along ensuring a minimum visibility of 10 m below a height of 2.5m and an air temperature of 60 ºC