Fires in Vehicular Tunnels

1. 12th North American/US Mine Ventilation Symposium An Overview Fires in Vehicular Tunnels Ian J. Duckworth, Ph.D., P.E.Senior Project Manager, Freeport McMoRan Copper & Gold(formerly Senior Program Director, Earth Tech)

2. Background • Thousands of road and rail tunnels are in service worldwide • Some meet modern safety standards • Majority do not • Major fire is one of the primary risks recognized by operators • Many modern tunnels safer, per kilometer, than above ground • Public perception and reaction to major tunnel fire • General public neither trained nor equipped to fight fires or evacuate under smoke conditions • Loss of life unacceptable 12th North American/US Mine Ventilation Symposium

3. Transportation Tunnels • Road Tunnels • Particular safety focus during last decade • Tunnels in service that do not meet modern standards • Large road tunnels may have +50 accidents/yr and +3 fires/yr - majority minor • Subways • Complex networks of tunnels and stations • New York: +1,000km track, 468 stations, 4.8 million ppd • London: +400km line, 274 stations, 2.7 million ppd • Original design for control of environment not fire / Passive • Heavily urbanized areas / Deep mined stations • Large transit systems may have +30 fires/yr – majority minor 12th North American/US Mine Ventilation Symposium

4. Road Tunnel Fires 12th North American/US Mine Ventilation Symposium

5. 1999 Mont Blanc Road Tunnel Fire • Major trans-Alpine road tunnel • 11.6 km long, 8.6 m wide, 4.35 m high • consists of single cross section with a two-lane dual-direction roadway • Managed by French and Italian public companies • 1999 fire resulted in 39 people losing their life • Initiated by refrigerated truck carrying 9t flour, 12t margarine & 550 l diesel • Fire burned for 56 hours, +1,000 °C, and spread to 40 vehicles 12th North American/US Mine Ventilation Symposium

6. Rail Tunnel Fires 12th North American/US Mine Ventilation Symposium

7. 2003 Taegu Subway Fire • Occurred February 18, 2003 • Initiated by an arsonist with gasoline • Fire destroyed two trains and caused many additional casualties at Jungangno Station • Duration of the fire ~ 3 hrs • 192 fatalities • Such fires have led to changes to the components of transit vehicles • More fire hardened • Smoke is less toxic 12th North American/US Mine Ventilation Symposium

8. What are Conditions Really Like? 12th North American/US Mine Ventilation Symposium

9. Typical Transportation Tunnel Safety Systems • Fire & smoke detection systems • Manual, opacimeters, temperature (linear, spot, array), air sampling, infra-red, UV, image recognition • Ventilation systems • Natural, vehicle-induced, mechanical • Traffic operation & information provision • Monitoring, tracking, CCTV, radio, phones • Escape and refuge facilities • Walkways, stairs, dedicated tunnel/plenum/adit, refuge bays, cross passageways • Fire suppression & rescue • Passive resistance, standpipe, sprinklers, hydrants, deluge, mist, screens, etc. • Other – power, lighting, tunnel management, etc. 12th North American/US Mine Ventilation Symposium

10. Some Design Considerations • Legislation & Standards • NFPA 130 & 502 • Performance vs. prescriptive design • Strict interpretation of design criteria and standards vs. application of engineered approach to demonstrate systems are safe • Practical yet sufficient • Maintainable “The major difference between a thing that might go wrong and a thing that cannot possibly go wrong is that when a thing that cannot possibly go wrong goes wrong, it usually turns out to be impossible to get at and repair.” Douglas Adams: Mostly Harmless 12th North American/US Mine Ventilation Symposium

11. More Design Considerations • Challenge of retrofit • Innovative solutions often required • Risk of delay – Acceptable? • Compromise – Acceptable? • Keep it simple – if possible • Source of funding – Federal, state, private, combination “Engineers like to solve problems. If there are no problems handily available, they will create their own problems.” Scott Adams 12th North American/US Mine Ventilation Symposium

12. Common Concepts • Tenability • Visibility (30m for lit sign) • Heat (temperature and duration) • Toxicity (combination vs. single gas) • CFD coupled with evacuation modeling • Fire Heat Release Rate • Rate of fire development, number of vehicles, flammable liquid spills, etc. Urban Vent Shaft Bangkok 12th North American/US Mine Ventilation Symposium

13. Simulation Software • One Dimensional • Integrated modeling of aerodynamic, thermodynamic and fire scenarios • Transient & dynamic requirement • Computation Fluid Dynamics • Prediction of hot smoke and gases from first principals • Requirement on most subsurface transit projects • Evacuation Modeling • Three dimensional modeling of people • Behavioral aspects • Coupling with CFD 12th North American/US Mine Ventilation Symposium

14. Conclusions • Fires will continue to occur in transportation tunnels • Responsibility of operators to ensure safety systems and procedures are adequate to cope with major fires • Design of fire-life safety systems for public subsurface facilities is a complex process • Standards – Compliance requirements • Constructability considerations • Retrofit for existing tunnels presents unique challenges • Consider the future • Tunnels, once built, are around for a long time • Facility upgrades will continue to be required 12th North American/US Mine Ventilation Symposium

15. Support Material 12th North American/US Mine Ventilation Symposium

16. Visibility & Smoke Concentration 12th North American/US Mine Ventilation Symposium

17. CFD Notes CFD analysis conducted by creating three-dimensional mesh models. The mesh consists of thousands of small cells or elements. The software solves the partial differential equations for the conservation of mass, momentum, species, turbulence scalars (k and epsilon), and energy in each cell. The simulation results provide air velocities, temperatures, pressures, and concentration of products of combustion. A time sequence of these results portrays the spread of smoke, the rise of temperatures, and the airflow patterns as they relate to evacuation routes. Time-squared fires are described in NFPA 92B as having slow, medium, fast and ultra-fast growth rates. Typical medium for transit and fast for road vehicles. Smoke production often based on 75% efficiency. Fire growth modeled by expanding the volume to which heat is added in steps. Transient and steady state simulation used. 12th North American/US Mine Ventilation Symposium