VEHICLE TUNNEL RISK REDUCTION BY ACTIVE FIRE SUPPRESSION AND SMOKE CONTROL

The paper advocates use of professional risk engineers and establishment of risk criteria to be met in vehicle tunnels. It outlines a methodology for establishing risk criteria and assessment of system effectiveness in risk reduction. It does not venture into the realm of quantification of risk, or of definition of a level of risk that the community will tolerate. The Australian experience in using fire suppression systems in conjunction with smoke management systems is reviewed, and outcomes of a professional risk engineering study outlined. The additional 2-3% overall new tunnel cost for a suppression system is concluded to be worthwhile. There is a growing perception in the community that risk can be eliminated; that if risk remains, it is the fault or responsibility of someone other than the individual involved. Professionals and government bodies are being held accountable for issues that previously have had an implied acceptance by the community, as a tolerable risk. Decisions to travel are taken with every expectation of safe arrival; even with the knowledge of road injury and fatality statistics. Whilst there is a tacit acceptance by the community of risk in road travel, largely based on the traveller’s past experience, there is little understanding of the potential increase in risk involved in tunnel travel, especially in “long” tunnels. Engineers thus far have been making the decisions on behalf of the community in the provision of facilities they deem to be at a level of tolerable risk and at a reasonable cost for the benefit provided, based on judgement and experience. This position is now challenged. Additional safety facilities and reduction of risk are now being demanded by the community, but with no means of defining what is tolerable, acceptable or affordable. The paper seeks to make a contribution to the on-going debate by suggesting a methodology for the assessment of risk and explores the relative merits and effectiveness in risk reduction, of tunnel configuration, fire suppression and smoke management systems, and operator and emergency services response to an incident.