Provisions for reliable and effective smoke detection in road tunnels: Fid-Bau Portal

Provisions for reliable and effective smoke detection in road tunnels

Buchmann, R. / Ruckstuhl, R.

Over the past years new technology has been provided to improve fire detection in road tunnels. One example is the trend to complement traditional linear heat detectors (LHD) with smoke detectors (SD). With this diversification one would expect a faster and more reliable detection. This approach is verifiably successful in shorter tunnels with or without longitudinal ventilation systems, where the simple detection of the fire is the primary goal. However in longer tunnels with smoke extraction ventilation systems, the detection system must also provide the fire location, which is a challenge for smoke detection systems. Due to the longitudinal air flow and/or the smoke-emitting vehicles travelling through the tunnel, smoke can be spread and remain over long distances and this alone makes it very difficult to reliably locate the fire source with a degree of accuracy. A wrong detection of the fire location with the corresponding ventilation scenario can produce a very undesirable situation for the tunnel users, even worse than without ventilation. This paper covers the following topics: (1) Discussion of smoke detection, (2) the necessity to differentiate between stationary and moving smoke sources, (3) well proven algorithm(s) to make this determination, (4) methods to test and verify the correct functioning o f the detection system, especially the smoke detection, (5) real examples.