Do Train Tunnels Need Ventilation Systems?

A planned new train tunnel under the central parts of Stockholm was intended to be ventilated by natural ventilation and the movement of the trains. However, the amount of heat generated by the trains is so high that natural ventilation would give abnormal temperatures and velocities in the tunnel and at the stations. The heat adsorbed by the rock surrounding the tunnel can be neglected in comparison with the amount transported by air. Some of the problems with the ventilation system are described and also the problems with dust generation by the trains and the exposure to dust at the stations by the passengers. The final decision was to use glass walls at the stations to separate the ventilation for the tunnel from that for the stations.