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96 layering will be difficult to contend with. Development of A new generation of video detection technology is some form of protection against thermal radiation is needed being developed. It includes volume sensors, which to assist tackling fires of this type, perhaps through the use search for fire and smoke within the entire observation of water mist jets or water curtain jets. Portable radiant bar- space of the IP address of the camera. This fundamen- riers and vehicles already in the tunnel are used for protec- tal advantage results in faster, more reliable fire and tion from thermal radiation. smoke detection and, most importantly, provides a visual picture of the situation to the on-duty operator. Some cameras are both UL listed and FM approved SUMMARY and have flame and smoke detection devices that are also FM approved. The cameras have passed tunnel Although each national and international standard provides tests in Canada, New York, and China. Use of camera- specific information related to design fire, most of the speci- based detection systems may fulfill many purposes if fied information addresses the same general performance the camera image can be used for security, traffic, concerns. This summary highlights some safety features that and/or road conditions. have limited or no recognition in NFPA 502, or a difference in approaches between NFPA and most of the other interna- Some international standards provide requirements in the tional standards noted. tunnels for: For ventilation design in the event of a fuel fire, sec- Shelters ondary explosions resulting from incomplete combustion Lay-bys need to be avoided. Therefore, the ventilation system Parallel escape tubes must be able to deliver enough air for the complete com- Separate emergency vehicular access gallery bustion or dilution of explosive gases. Cross-passage vehicular access PIARC documents and other international standards Emergency lanes Direct pedestrian access (lateral, upstairs, shaft) allow longitudinal ventilation in single-tube nonurban Turning areas tunnels with 2-way traffic based on risk analysis relying Emergency services station at portals. on smoke stratification, although this is not recom- mended in the United States. Such requirements are not found in NFPA 502 and need No European standards have requirements for installa- additional studies of the experience from international tion of a fixed fire suppression system. Such require- standards. ments exist in Japan and Australia: In Australia, AFAC (the Australian Fire Authorities Recently, intelligent evacuation notification technol- Council) strongly advocates the installation of suit- ogies were developed using electroluminescent lighting ably designed, manually controlled, deluge/sprinkler technology--an uninterrupted illuminated path to the exits systems. with a continuous light source located near the walkway In Japan, sprinkler systems are required for Class AA floor or multi-directional low-level LED guidance system. tunnels, Class A tunnels more than 3000 m long and The advantage of those technologies is that they can be pre- average daily traffic of more than 4,000 vehicles/day, programmed to direct tunnel users in the right direction depend- and for bi-directional tunnels. Sprinkler systems have ing on ventilation system response. This is especially important been installed in more than 80 tunnels in Japan. when complicated tunnel ventilation schemes are used to In Sweden, fixed fire suppression systems would be eliminate the wrong direction for evacuation. installed if leading to a significantly raised level of safety for people according to risk analysis. The following common gaps in the national and interna- Automatic fire detection with no allowance for man- tional standards and regulations were reported: ual fire detection is required by many international standards. The regulations and guidance need to provide better con- In a few national guidelines for road tunnels there are sideration of the interactivity of all systems that interact values for the maximum detection time and degree of in a tunnel. Integrated approaches shall be applied to accuracy of fire location, including fire loads and air- tunnel fire safety. flow speed. Fire-detection time is a critical element Better identification with regard to human behavior of in a tunnel fire event. Detection time depends on fire both tunnel users and operators, as well as identification development and ventilation conditions and varies of the means to improve safety. from 1 to 2.5 min. Maximum design detection time is Consideration shall be given for technical innovations directly related to fire development. that allow more ambitious safety objectives.