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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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