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the severity of incidents, consequences of fires, human re- tionnaires completed by tunnel owners and agencies regarding
sponse, structural response, systems response, emergency re- best practice in tunnel safety.
sponse teams, and tunnel operators.
This study synthesizes the available information, prac-
The design fire parameters used for the design of tunnel tice, and knowledge related to design fires in road tunnels
emergency ventilation and fire life safety systems have a sig- and identifies gaps in that information to provide a founda-
nificant impact on the tunnel design and users' safety. The key tion for design guidance. A design fire is characterized by a
criteria are the fire size and heat release rate (HRR), fire growth number of parameters including the temperature, fire heat
and decay rate, smoke production, resultant temperatures, and release rate (FHRR), fire growth rate, fuel load, and products
fire duration. If both the growth rate and the peak fire size are of combustion.
assumed to be too slow in the early design stage, the design
changes may result in additional surface penetrations, larger The sources of information used for developing this syn-
fan plants, and additional spaces and evacuation routes. thesis included the literature search, a survey, and interviews
with the following stakeholders: owners, operators, designers,
More than 30 years ago minimum attention was paid to emergency responders, government agencies, relevant pro-
fires in tunnel design. Tunnel ventilation system design was fessional associations, and so forth. The literature search in-
driven by carbon monoxide (CO) dilution requirements for cluded national and international standards and guidelines on
normal operation and the American Society for Heating, road tunnel safety; publications of international organizations
Refrigeration, and Air Conditioning (ASHRAE) recom- such as the World Road Association (Association mondiale
mendations of 100 cfm/lane/ft (0.155 m3/s/lane/m) of supply de la route; PIARC), United Nations, and European Union;
and exhaust airflow. However, tunnel accidents in recent reports on major international studies; papers presented at
years have drawn widespread attention to the risks of fires national and international symposiums; and books, magazines,
in tunnels with two distinct consequences. First, the fires and other publications.
themselves have resulted in fatalities, injuries, and struc-
tural damages, as well as lengthy tunnel shutdowns result- The objectives of this study were to:
ing in adverse economic impacts. Second, the perceived risk · Document significant fire incidents, domestic and inter-
of fire is also likely to have discouraged tunnel use and, in national, in road tunnels.
some cases, the actual construction of tunnels. · Review existing data from fire tests in road tunnels and
identify gaps in testing.
NFPA 502: Standard for Road Tunnels, Bridges, and Other · Collect data on the application and effectiveness of
Limited Access Highways, updated in 2011, is the primary fixed fire suppression systems and how these might
national document that provides guidelines for fire and life modify the design fire size.
safety requirements for U.S. road tunnels. This standard is gen- · Document the effects of various ventilation conditions,
erally updated every 3 years based on the latest information on tunnel geometry, and structural and nonstructural com-
tunnel fires, development of technology, and the experiences ponents of a tunnel on design fire characteristics.
of tunnel owners, agencies, first responders, designers, and · Document the impact of alternate fuel vehicles on design
vendors. The latest Standard includes 13 chapters and an fires.
annex of explanatory material that covers limited access high- · Present design fire issues relevant to fire suppression
ways, bridges, road tunnels, and roadways beneath air-right system designs and gaps in available information.
structures and sets design requirements for fire life safety sys- · Establish the state of practice in computer and scale-
tems, structures, and emergency response procedures. modeling efforts.
· Provide exit strategies and motorist notification systems.
ASHRAE established Technical Committee TC 5.9 on · Review design guidance information on the issues that
Enclosed Vehicular Facilities to address tunnel safety issues need to be considered in setting design fire sizes and
during bi-annual ASHRAE meetings through conferences, establishing next steps.
transactions, forums, and seminars. · Seek out information on combined use tunnels.
Since 1999, a number of major tunnel fire incidents have DESCRIPTION OF THE SURVEY PROCESS
occurred in Europe. As a result, several international and
European research projects have been focused on the design The survey process involved the development and distribu-
for controlling fires. Ample experience comes from Australia tion of an on-line questionnaire that focused on identifying
and Japan, who have also had major tunnel fires. Every year the range of current practices in design and procedures that
there are a number of international conferences, symposiums, deal with fires in road tunnels. The primary candidates for
forums, and seminars on tunnel safety and the ventilation of completing the questionnaire were transportation agency staff,
vehicular tunnels. This synthesis project focuses on the latest primarily at the state DOT level, to obtain as broad a repre-
international experience and knowledge in the design of con- sentation of current tunnel fire management practices as pos-
trolling tunnel fires, as well as the survey results from ques- sible. Input was solicited from the national tunnel agencies
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and operating authorities. The same questionnaire was sent to Questionnaire recipients were asked to either complete
international agencies in Canada, Australia, Hungary, Korea the questionnaire themselves or forward the questionnaire
and Sweden. The questionnaire responses were a vital source to another, more appropriate individual within their agency.
of information for this study. In addition, a recipient could choose to forward the ques-
tionnaire hyperlink to individuals in multiple divisions
The questionnaire information was also distributed at the within the agency.
winter 2010 ASHRAE Meeting of the Technical Committee
5.9 on Enclosed Vehicular Facilities to solicit voluntary Chapters two through seven, nine, and thirteen document
participation. the literature review; results of the survey are summarized in
chapter eight; chapter ten compiles design guidance, stand-
The questionnaire was administered in the following ards, and regulation; chapter eleven reviews design fire sce-
manner: narios for fire modeling; chapter twelve discusses fixed fire
· A targeted list of key individuals at state DOTs was suppression; and chapter fourteen presents the conclusions
developed. Topic Panel members reviewed the survey and areas for further study.
distribution list and made changes where necessary and
added contact information for any suggested agencies Appendix A includes the survey questionnaire, Appendix
to include in the survey. B is a list of the responding agencies, and Appendix C is the
· Electronic copies of the questionnaire were distributed Summary of the Survey Questionnaire Responses. Appen-
to any willing participants. dixes D through G present web-only information on tunnel
· Nonrespondents at state DOTs were contacted with safety projects, fire tests, national and international standards
follow-up reminders to encourage responses. requirements, and past tunnel fires.
