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mosen mosen
Fire Protection and Safety in Tunnels Conference –
Opening Remarks
Dr Fathi Tarada
Secretary, PIARC Tunnel Operations Committee
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Agenda
• Background to the conference
• Key themes
• Recent tunnel fires
• Major infrastructure projects
• Questions and challenges
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Background to the Conference
• Spending on new infrastructure projects worldwide
• Maintenance and refurbishment of existing tunnel stock
• Recurring fires and incidents in tunnels
• Investment decisions on how to balance safety and cost-efficiency
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Key Conference Themes
• Development and harmonisation of national, European and global standards –RABT, TSIs, PIARC
• Information from full-scale fire tests –METRO project
• New technologies – automation, fire suppression, passive fire protection
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Recent Tunnel Fires
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Brynglas Tunnel Fire, South Wales
• 26th July 2011• Lorry fire in westbound tunnel tube• Severe traffic disruption for 4 days• Extensive clean-up and repairs required
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Simplon Rail Tunnel Fire
• 9th June 2011• Fire on goods train, 3 km from Italian portal• Fire spread to 10 other goods carriages• Damage to tunnel and rail infrastructure• Severe traffic disruption
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Østfold - Hurum Fjord Tunnel, Oslo
• 24th June 2011• Truck fire• Fire brigade needed to evacuate tunnel• Five persons treated for smoke inhalation
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Key Issues from Real Tunnel Fires
• Life safety – for tunnel users and emergency responders
• Traffic disruption – impact on local, regional and national economy
• Tunnel damage – structure and installations
• Secondary impacts – toll collection, diversion routes, reputation
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Major Infrastructure Projects
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Crossrail Project, UK
• Largest construction project in Europe
• Will connect 37 stations linking Maidenhead and Heathrow in the west, to Shenfield and Abbey Wood in the east
• 21 km of new twin-bore tunnels under central London.
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Crossrail – Tunnel Ventilation
• 8 underground stations
• Ventilation shafts at each end of station
• Two additional intervention/ventilation shafts
• Smoke control in case of train fire
• Cooling in case of train breakdown
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Jack Lynch Tunnel, Ireland
• 610m long immersed tube tunnel
• Joints particularly vulnerable
• Passive fire protection being installed to protect against 100MW fire scenario
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Qatar Integrated Railways Project
• 107 stations and more than 130 km of tunnels (Doha Metro with Red, Green, Golden and Blue Line; Long Distance Line for passenger and freight service)
• Tunnel ventilation for cooling, air quality and smoke control
• Station-based ventilation shafts
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Questions and challenges
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Challenge the speakers …
• Is this safety system really necessary?
• What design basis has been used?
• Where is the cost/benefit evidence?
• What is the track record?
• Is this safety system feasible for my application?
• How can I apply the technology to my project/infrastructure/tunnel?
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Evolving Standards and Practices in Tunnel Fire Safety
Dr Fathi Tarada
Managing Director, Mosen Ltd
Chief Executive, HBI Haerter Ltd
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Agenda
Design Fires for Tunnels
• Key factors
• Latest PIARC guidance
Air Quality in Tunnels
• Changes in vehicular emissions
• Latest PIARC guidance
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Design Fires for Tunnels
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Fires in Tunnels – Key Factors
• Trigger events: accidents, mechanical failures• Combustibles: vehicles and contents
– Hydrocarbons (petrol, diesel, fat, ...)– Dangerous goods
• Fire spread from vehicle to vehicle – Tauern Tunnel: fire ‘jumped’ over 130m
• Tunnel airflow– Higher airflow can cause more intense fire
• Tunnel geometry– Smaller cross-sections can lead to radiative
‘feedback’
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Fire Heat Release Rates
• Research projects such as UPTUN have suggested much higher fire heat release rates are possible
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UPTUN Fire Heat Release Rates
• T1 = wood and
plastic pallets
• T2 = wood
pallets and
mattresses
• T3 = furniture
• T4 = plastic
(PS) cups in
cardboard
cartons
• Temperatures
up to 1300 °C
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But …
• Small tunnel cross-section
• High radiative feedback
• Tarpaulin covers
• High airflow velocities
Is this representative of tunnels?
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Latest PIARC Guidance
• Previous: prescriptive approach, specific fire size depending on type of vehicle
• Performance-based approach now possible
• Design fire is not largest possible fire
• Conscious choice of design fire and residual risk required
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START
1
TUNNEL GEOMETRY TUNNEL LOCATIONTRAFFIC
· Normal / congested
· Bi / unidirectional
· Dangerous goods
· HGVs
· Traffic Density
· Cross-section
· Height
· Slope
· Length
· Intersections
· Urban / rural
· Climate
· Altitude
DESIGN FIRE
CHARACTERISTICS
· Q/t curve
· HRR peak value
· T/ t curve
2
DESIGN OBJECTIVES
Evacuation Fire fighting Asset protection
Estim
atio
n o
f
fire
ha
za
rd
Fire
sa
fety
leve
l
req
uire
me
nt
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Longitudinal vs. Transverse Ventilation
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Typical Design Fires
• Longitudinal ventilation: 100 MW
• Transverse ventilation: 30 MW
• Is this difference justifiable?
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Fire Heat Release Rates
• Fire heat release rates increased from last PIARC report
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Longitudinal vs. Transverse Ventilation
• Lower capital costs for longitudinal ventilation -higher fire heat release rates can be designed for
• Better smoke confinement in transverse ventilation systems
• Different residual risks – may be acceptable
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Design Fires in Tunnels
PIARC’s latest guidance:
• Substantial increase in design fire heat release rates
• Designers and authorities have responsibility for selections
• Residual risk is always present – choice of tolerable risk required
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Tunnel Air Quality
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Key air quality measures
• CO – ‘traditional’ measure
• Visibility
• NOx – becoming increasingly critical
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New PIARC Air Quality Report
• New vehicle emission standards – EU5 and EU6
• Two vehicle emissions calculation schemes:
– Simple methodology with 2010 base year, with country-specific factors
– Detailed emissions calculations based on vehicle-specific factors
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Fleet Segmentation
• Passenger cars gasoline & diesel
• Light-duty vehicle
• Heavy-goods vehicles and buses
• Vehicles using alternative fuels (alcohol, compressed natural gas)
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Country-Specific Factors
• Obtained from questionnaires of various countries
• Emission factors specified for:
– Euro standards
– Australia
– Algeria
– China
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NOx
• NO2 – can affect both healthy and sensitive individuals
• For healthy people, effects have been noted for peak levels higher than 4000 μg/m³ observed
• Impacts motorists within tunnels and external air quality
• PIARC proposes an in-tunnel air quality limit of 1 ppm for NO2
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Emission FactorsEmission factors dependent on:• Vehicle type• Speed• Gradient
Correction factors for:• Altitude• Year (if different from base year)• Technology standard• Vehicle gross mass• Non-exhaust particulate emissions
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Tips for the Unwary
• Ventilation equipment may be oversized if congested or stopped traffic is assumed over the entire tunnel length
• Percentage of HGVs quoted as an average; this may be too high for peaktraffic flow
• Large uncertainties in non-exhaust particulate matter emissions due to re-suspension and abrasion
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New PIARC Air Quality Report
Key Points:
• Reducing trend of vehicular emissions captured
• Increasing importance of NO2 as air quality issue
• Alternative calculation schemes proposed
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www.mosenltd.com