A Tunnel Fire Main is part of the fire protection infrastructure provided within railway tunnels to supply water for firefighting operations.

The system generally consists of a dedicated water main running along the tunnel, connected to strategically located hydrants, landing valves or other firefighting connection points. It enables emergency responders to obtain a reliable water supply close to the location of a fire without having to run long hose lines from outside the tunnel.

Depending on the railway and fire strategy, the fire main may be continuously pressurised as a wet system, or designed using another arrangement appropriate to the environmental and operational conditions. Pumps, water storage, isolation valves, pressure monitoring and sectionalisation may form part of the overall system.

Tunnel fire mains require coordination with tunnel cross passages, emergency access points, shafts, evacuation routes, walkways, equipment rooms and other fire and life-safety systems. The arrangement should allow sections of the system to be isolated for maintenance without unnecessarily removing firefighting capability from large portions of the tunnel.

Design considerations include required water flow and pressure, hydrant spacing, pipe sizing, redundancy, pressure losses, accessibility, corrosion protection, drainage, maintenance and protection of the pipework from railway operational hazards.

The Tunnel Fire Main forms part of the wider tunnel Fire and Life Safety (FLS) strategy and operates alongside systems such as fire detection, emergency communications, Tunnel Ventilation System (TVS), emergency lighting and evacuation provisions.

mainline, high_speed, metro, light_rail, freight

NFPA 130 where applicable; NFPA 14 where applicable; local civil defence and fire authority requirements; applicable railway tunnel fire and life-safety requirements