Rail and metro tunnels are long (>1 km) with limited exits - egress is critical. NFPA 130 (Fixed Guideway Transit and Passenger Rail Systems) defines Fixed Firefighting System (FFFS), longitudinal ventilation and evacuation rules. Examples include Marmaray, Eurasia and the Channel Tunnel.
HRR Scenarios
- Metro car: 7-10 MW (EN 45545-2 R1-R24 class)
- Freight car: 50-100 MW (Eurotunnel HGV shuttle)
- TGV/Velaro: 15-25 MW
- Peak HRR 10-15 min: design verification via CFD
Longitudinal Ventilation
- Critical velocity: 2.5-3 m/s (prevents backlayering)
- Jet fan: every 100 m, 2 x 250 kW
- Portal fan: large fans at tunnel mouth
- Smoke damper: zone isolation
- CFD: Froude + Richardson number validation
Water Mist FFFS
- High pressure: 100 bar, 1 L/min/m2
- Nozzle spacing: 3 m longitudinal, 2.5 m transverse
- Activation: linear heat detection (Listec) + CCTV
- Zone: 200 m sections, only 1 zone active
- Reserve: 90 min = ~200 m3 (10 m3/min x 20 min two zones)
Egress Route
- Cross passage: every 250 m connecting twin tubes
- Pressurization: cross passage +50 Pa
- Walkway: rail level, 1.2 m width
- Emergency light: LED, 90 min battery, 10 lux
- Evacuation time: 1,000 pax, 2 km tunnel - 10-15 min target
International Examples
- Channel Tunnel: 50.5 km, FFFS added after 1996 fire
- Marmaray (Istanbul): 13.6 km, FFFS + twin portal fans
- Eurasia Tunnel: 5.4 km, 2x2 lane road - NFPA 502
- Gotthard Base (Swiss): 57 km, jet fans + fixed water spray
Tunnel FFFS with SprinkCalc
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Sources & Further Reading
NFPA 130, NFPA 502, PIARC Road Tunnel Guidelines, EN 45545 Fire Safety Rail. NFPA 130 Rail Transit standard.