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Water mist fire fighting systems safeguard human lives and tunnel structures

June 2022

Water mist fire fighting systems
Full fire test of a water mist fire-fighting system with a reconstructed lorry. Photo: FOGTEC Brandschutz GmbH

The devastating tunnel fires of the past which claimed numerous lives have shown that large fires can occur even in modern tunnels, and they may have the potential to develop in a dramatic way. As the fire grew rapidly in size and radiated heat, a manual intervention by fire brigades was often not possible any more. Motorists and also the operational capability of the fire brigades were at considerable risk. In many cases, the fires damaged the tunnel structure so severely that the subsequent repair work required long closure times. FOGTEC Brandschutz GmbH has carried out research projects to investigate the effectiveness of water mist fire fighting systems.

The fire risks in connection with the safety of human lives, the safety of fire brigades and the protection of tunnel structures are sufficiently well known and the specifications, especially with regard to the safety of persons and the protection of structures, are recorded in sets of rules. In order to fulfil these, various concepts and fire protection measures can be implemented. For about 20 years, water mist fire fighting systems (WM-FFS) have been used in selected tunnels to fight large fires. One of the fire fighting agents is usually pure water. Within the framework of research projects funded by the German government and the European Union, FOGTEC has carried out real fire tests in specially designed test tunnels to investigate the effectiveness of the systems.

Reducing life cycle costs

It was shown that WN-FFS significantly reduce the risk of fire by limiting the size of the fire and preventing the spread of the fire from one vehicle to another. In the event of a fire, the cooling effect of the water mist in particular significantly reduces the temperatures around the fire and limits heat radiation. This increases the safety of motorists and firefighters significantly. Increasingly, these advantages of FFS are also being used to protect the tunnel structure.

The availability of tunnels is becoming more and more important. Fires sometimes lead to considerable damage, significant repair costs and long closure times of important traffic arteries. They drive up the life cycle costs of such a structure. FOGTEC’s fire fighting systems can shorten the closure times quite considerably.

Tunnels can be reopened to traffic in the shortest time possible. The comparison between maintenance and initial costs of such a system and the increased life cycle costs caused by a fire shows that in many cases the investment in a FOGTEC FFS pays for itself after only a few years.