External detection of fires on moving trains

On behalf of the Italian State Railways (RFI), SP is investigating the feasibility of detecting a fire on a train on its way into a tunnel.  If a fire is detected, the train should stop before entering the tunnel.  SP Fire Technology is working in conjunction with FOI and Thermal System Technologies in Linköping.  The main detection systems will probably be IR cameras or absorption measurements.

A risk analysis ordered by RFI found it to be an effective mean of reducing the risks of fire in a tunnel through external detection of fire on or in a train.  Work has already started in Italy with the installation of checkpoints for the detection of fire a few kilometres before tunnels.  However, the problem is that it is not a simple matter to detect a fire on a train passing the checkpoint at 150 km/h.  RFI therefore contacted SP to assist in improving detection.

The project is evaluating the detection of flames or fire gases through the use of IR cameras.  However, it is expensive to stop trains unnecessarily, and so false alarms must be avoided, imposing stringent performance requirements on the detection system.  For this reason, absorption measurements may show themselves to be a more reliable method for future evaluation.  Measuring the absorption of particular optical wavelengths is a powerful tool used in combustion physics for measuring the concentration of various substances and compounds in flames and fire gases.  Although this is a common method in combustion physics, it is seldom used for fire detection.  Spectrally resolved absorption measurements can be used as an important means of identifying fire and exhaust gases from combustion engines and fires, helping (for example) to avoid false alarms from diesel engines.