Airflow testing
These measurements make it possible to define or check the ventilation conditions in the tunnel according to the weather conditions outside and the traffic. In the event of a fire, the air flow in the tunnel must be stopped to slow the spread of the flames.
Measurements of speed, traffic, temperature and humidity are taken in the tunnel and around the tunnel heads, with and without traffic. The data is analysed with the nearest permanent recorder, the concession holder’s weather station or the Météo France weather station.
The results of the analysis show the relationship between the natural ventilation speed and the measurements of wind and atmospheric conditions from the permanent station and the traffic. This enables the concessionaire to check the sizing of its ventilation systems on the basis of estimated return times for extreme weather conditions, and to draw up adjustment tables for its mechanical ventilation.