Design Fires in Road Tunnels (2011) / Chapter Skim
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Chapter Fourteen - Conclusions
Chapter Fourteen - Conclusions
Pages 116-122
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From page 116... ...
This helps us to better understand tunnel fires and the safety means to prevent them and to protect tunnels. The most important documented projects are: • FHWA Prevention of Tunnel Highway Fires • TRB/NCHRP Making Transportation Tunnels Safe and Secure • International Technology Scanning Program sponsored by FHWA and others • UPTUN, European Project (EP)
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From page 117... ...
Advantages: - Partial results with full-scale facilities - Numerous different situations Disadvantages: - Lack of information due to the limited number of sensors Conclusions: - Useful but partial results Advantages: - Accumulation of experience useful to choose a system - Test performed with real ventilation systems Disadvantages: - Limited number of tests Conclusions: - Useful Advantages: - Shows to the operators how the ventilation reacts - Fire departments are very interested in expected situation Disadvantages: - No operation possible during the tests Conclusions: - Well suited Tunnel Fire Tests Before or Under Operation (aimed at operators and fire department training) Advantages: - Visual observations possible Disadvantages: - Lack of information due to the absence of sensors Conclusions: - Not suited Advantages: - Test performed with real ventilation systems Disadvantages: - Limited analysis due to the lack of measurements Conclusions: - Not well suited Advantages: - Representative situation Disadvantages: - No operation possible during the tests Conclusions: - Well suited Reduced Scale Models Advantages: - Many tests possible - Possible to study global laws governing specific situations Disadvantages: - Needs full-scale reference tests for transposition to real situations Conclusions: - Useful method for research Advantages: - Cost lower than full-scale tests Disadvantages: - Linked to the limitations induced by the similarity laws Conclusions: - Very difficult to conclude that the results are representative of full-scale situations Advantages: - Cost Disadvantages: - Linked to the limitations induced by the similarity laws - No respect of time basis Conclusions: - Possibly unrealistic but demonstrative Numerical Models (CFD)
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From page 118... ...
design and assessment; • For egress analysis; • For thermal action on structures; • For the safety of tunnel fire equipment; and • For work on tunnel construction, refurbishment, repair, and maintenance. A design fire scenario represents a particular combination of events associated with: • Type, size, and location of ignition source; • Type of fuel; • Fuel load density and fuel arrangement; • Type of fire; • Fire growth rate; • Fire's peak HRR; • Tunnel ventilation system; • External environmental conditions; • Fire suppression; and • Human intervention(s)
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From page 119... ...
There are many types of tunnel ventilation systems. Time Dependent Design Fire Variables Values Range Design fire variables are a function of: Fire Size -- Maximum FHRR (1.5 MW–300 MW)
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From page 120... ...
It allows for predicting how long the environment will be tenable in the tunnel and helps to decide what needs to be done to achieve fire life safety goals. A fire suppression industry offers to control the fire size, reducing the maximum HRR and fire growth by applying a fixed fire suppression system.
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From page 121... ...
2. Operation and commissioning • International practice of commissioning tunnel fire life safety equipment and fire fighting procedures using hot smoke tests and burning actual vehicles in the tunnels needs to be evaluated for future national standards' considerations.
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From page 122... ...
• Further development of tunnel ventilation systems, and the ventilation response in conjunction with other systems, such as fixed fire suppression systems. • Regulations and guidance need to provide better consideration of the activity of all systems that interact in a tunnel.
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