Road longitudinal

Overview

In normal operating conditions the Tunnel Ventilation System has to keep the air quality and the concentration of pollutants within safety levels. In emergency conditions, the Ventilation system is designed to control or extract smoke to allow fast and safe evacuation and fire fighting activities. This means that the fans have to be High Temperature certified by a 3rd Party.

Longitudinal ventilation systems generally use jet fans installed on the tunnel ceiling/walls.

The main advantage of this type of Ventilation System is that the costs both for installing and for maintaining are relatively low.

In order to control the smoke, the fans have to be reversible in bi-directional tunnels and can be either uni-directional or truly reversible in uni-directional tunnels.

Jet Fans have to be resistant to corrosion due to the salt used in winter time in mountains areas, or for tunnels located by the coast including undersea tunnels.

If the is no space available in the Tunnel for Jet Fans, another system can be used: Saccardo Ventilation where instead of Jet Fans, the system uses banks of large axial fans in parallel fitted with special nozzles to accelerate the air inside the tunnel.

Success Stories

• M25 Bell Common Tunnel, UK
• M25 Holmesdale Tunnel, UK