Toxicity Limit States in Tunnel Fire Safety Designs

The Mont Blanc tunnel fire March 1999 killed 39 persons, of which most died within 15 min due to intoxication. In Norway there have been several fires the recent seven years. No single road-user has died from intoxication in those fires, in spite of being engulfed with smoke for more than 1.5 h. The tunnel safety discourse amongst tunnel owners and researchers turns towards questioning whether current longitudinal ventilation strategies can be used to design the tunnel system to meet the self-rescue principle. Smoke control would then be the design criterion. The Norwegian Public Roads Administration could in this perspective re-duce its effort to invest in safety measures ensuring safe havens for road users trapped in smoke and other fire preventive measures. We are very critical to such a development of tunnel fire safety. This paper raises questions about predictability of smoke dispersions in case of tunnel fires as well as human tolerability of toxic gases from fires. We conclude with issuing designs of research studies to reduce the gaps of knowledge revealed in the literature.