Design Fires in Road Tunnels (2011) / Chapter Skim
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Pages 96-103
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From page 96... ...
Fire scenarios are used for the following: • Design of emergency exits, • Choice of a fire-detection system, • Choice of ventilation and fire suppression systems, • Tunnel structural engineering, • Specification requirements for tunnel structures and equipment, • Operation of the tunnel, and • Training of operators and first responders dealing with tunnel fires. Fire scenarios usually include: • Governing standards and guidelines; • Description of the scenario; • Thorough definition of the fire parameters (e.g., HRR/ temperature versus time)
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From page 97... ...
for at least 90 min. RABT 1994, Germany 4 Designing of a longitudinal ventilation system with jet fans capable of controling a truck fire event with a calorific heat output of approximately 20 MW (68 MBtu/hr)
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For large tunnel fires, the tunnel linings in the vicinity of the fire are primarily affected by this incident flame radiant heat flux. The project shall develop a time-of-tenability criteria based on the design maximum HRR.
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From page 99... ...
However, the use of HRR curves for the design is often allowed. When using HRRs instead of time–temperature curves for calculating structural stresses resulting from a fire, a super fast increase of the HRR is to be used as it was observed with the Runehamar tests in Norway in late 2003.
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From page 100... ...
Depending on the number of evacuees (occupant load) , a bottleneck may form approaching the cross passages or egress stairs.
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From page 101... ...
The primary role in system activation is fire detection. Thus, spacing between cross passages will largely depend on the fire-detection system.
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From page 102... ...
SUMMARY A fire scenario must be designed to get an optimum fire life safety strategy for road tunnels. Fire scenarios are used for the following: • Design of emergency exits • Choice of a fire-detection system • Choice of ventilation and fire suppression systems • Tunnel structural engineering • Specification requirements for tunnel structures and equipment • Operation of the tunnel • Training of operators and first responders dealing with tunnel fires.
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From page 103... ...
3. Equipment activation time consists of the following phases for supervised tunnels: • Fire-detection time • Fire alarm and operator reaction time • Time to bring the first group of fans to full speed • Time to activate the fixed fire suppression system if desired • Achieve a full operational mode for ventilation system.
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