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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.
