Safety and Reliability of Fire Detection Systems in Road Tunnels

Fourth International Symposium on Tunnel Safety and Security, Frankfurt am Main, Germany, March 17-19, 2010
Figure 3: Loop configuration of MHD 535 temperature sensor cable with increased availability
Max. 2000m, 250 Sensors
RXG Control Unit
RCU Relais Control Unit
CPMSSM
SSM 2 SSM SSM SSM CPM ECB Earth Connection
rests
CPM Overvoltage Protection
ECB
functional
ECB SSM Separator Module
Short circuit
Interrupt
RXG
RCU (up to 6 pcs.)
RXG
32 Relays
2 Relays (Alarm, Fault)
8 Group relays
RS232
FT-NET
CONCLUSION
For the automatic detection of tunnel fires and the subsequent initiation of cost intense fire ventilation
and fire brigade alarm, linear heat detectors today are the only 100% reliable detector with a minimum
of fault alarms. However systems with the possibility of reaction by temperature gradient have to be
used, as the maximum temperature for a car fire might not reach more than 50 °C. They fulfil all
requirements including the required detection speed of 60 seconds for a 5 MW fire even at high air
speed of 10 m/sec. For an optimized solution, the use of redundant systems restricting errors to single
instruments or segments is recommended. For tunnel showing a high risk for fires, several different,
independent detection technologies are recommended. At least one system should give an automatic
reaction to the fire scenario.
Smoke detectors or visibility monitors should be used in addition for early fire detection as already
mandatory in Germany and Switzerland. Today their signals have to be confirmed by the control room.
In some applications, they start automatically the fire ventilation. With more experience in their
application and on possible thresholds and interference, they might be used for automatic triggering of
the complete fire alarm scenario, too. Video detection is due to its non negligible fault alarm rate a
sensitive subject. However in tunnels with a high risk potential they might contribute to increase the
safety.
It is recommended that the most reliable system –usually the temperature based detection – triggers
automatically the alarm scenario. This helps to prevent any loss of alarms due to human failure.
REFERENCES
1. A. Rogner, “Fire Detection in Tunnels – An Actual Overview on Technologies and Systems”,
2nd Tunnel Safety Forum, Lyon, France, April 20-22, 2009.
2. Richtlinie für die Ausstattung und den Betrieb von Strassentunneln (RABT), Ausgabe 2006,
FGSV-Verlag
3. Richtlinie Branddetektion in Strassentunneln ASTRA 13004, Ausgabe 2007 V 2.10
4. RVS 9.282 – Projektierungsrichtlinien, Betriebs- und Sicherheitseinrichtungen –
Tunnelausrüstung, Ausgabe 07/2002, FSV Wien
5. Brand- und Störfalldetektion in Straßentunneln - Vergleichende Untersuchungen [FGSV-Nr.
Heft 925], 2005, ISBN 3-86509-357-4
6. Grässlin, Urs: „Erfahrung aus dem Gotthardstrassentunnel durch Einsatz der Sichttrübung und
Rauch-, Branddetektion“, Proceedings of 6th Symposium „Sicherheit im Strassentunnel
durch Einsatz moderner Messtechnik“, Sigrist-Photometer AG, Brunnen, 2007
KEYWORDS: Fire detection, tunnel safety, line type heat detectors, smoke detection, video detection,
redundancy
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