Evolving Needs of Tunnel Ventilation in a Changing World

The role of road-tunnel ventilation has changed during the last decades. While in former years tunnel ventilation was responsible for providing an acceptable environment for tunnel users passing through the tunnel during normal operation conditions [30], nowadays the support of rescue conditions during a fire is dominating. The introduction of the fire case into the ventilation design resulted in increased demands and led to a remarkably increase in extraction volumes and ventilation powers. Ventilation control which in former years focused on maintaining the in-tunnel air quality has now become a very complex tool in order to fulfil the requirements for supporting self-rescue possibilities in case of an incident. A second issue, which becomes increasingly important, is the environmental impact caused by the polluted tunnel air. Portals and air exchange stations in built-up areas call for intelligent control of the air flows and even in some special cases for exhaust-air treatment systems. For tunnels with severe air-quality constraints at the tunnel portals, significant ventilation power is required.