This study investigates steps that can be taken to reduce the risk, damage, and fatalities from fires in existing and future highway tunnels and the effect of unrestricted transit of hazardous materials through them. The history of highway tunnel fires is examined to discover the design and operating features bearing on ignition, spread, detection, alarm transmission, response, control, resulting damage, and survivability aspects. Major domestic highway tunnel operators are interviewed concerning tunnel fires and their responses tabulated and compared. The procedures and results of several tunnel fire tests are examined and their recommendations evaluated in the light of historical evidence and operating experience concerning tunnel fires. A risk analysis for unrestricted transit of hazardous materials through a reference tunnel is performed and applied to 35 tunnels included in the study. Qualitative assessments of the effects of traffic, tunnel design, and operations on this risk are made. Comprehensive design and operating recommendations for prevention, detection, alarm, notification, control, extinguishment, suppression, and survival are developed. A ventilation system with a fire/emergency operating mode designed to provide motorists trapped in a tunnel fire with optimum escape potential is described and its inclusion in future vehicular tunnels recommended. (Author/publisher)
Abstract