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Design Fires in Road Tunnels (2011)

Chapter: Chapter Fourteen - Conclusions

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Suggested Citation:"Chapter Fourteen - Conclusions." National Academies of Sciences, Engineering, and Medicine. 2011. Design Fires in Road Tunnels. Washington, DC: The National Academies Press. doi: 10.17226/14562.
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Suggested Citation:"Chapter Fourteen - Conclusions." National Academies of Sciences, Engineering, and Medicine. 2011. Design Fires in Road Tunnels. Washington, DC: The National Academies Press. doi: 10.17226/14562.
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Suggested Citation:"Chapter Fourteen - Conclusions." National Academies of Sciences, Engineering, and Medicine. 2011. Design Fires in Road Tunnels. Washington, DC: The National Academies Press. doi: 10.17226/14562.
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Page 119
Suggested Citation:"Chapter Fourteen - Conclusions." National Academies of Sciences, Engineering, and Medicine. 2011. Design Fires in Road Tunnels. Washington, DC: The National Academies Press. doi: 10.17226/14562.
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Page 119
Page 120
Suggested Citation:"Chapter Fourteen - Conclusions." National Academies of Sciences, Engineering, and Medicine. 2011. Design Fires in Road Tunnels. Washington, DC: The National Academies Press. doi: 10.17226/14562.
×
Page 120
Page 121
Suggested Citation:"Chapter Fourteen - Conclusions." National Academies of Sciences, Engineering, and Medicine. 2011. Design Fires in Road Tunnels. Washington, DC: The National Academies Press. doi: 10.17226/14562.
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Page 122
Suggested Citation:"Chapter Fourteen - Conclusions." National Academies of Sciences, Engineering, and Medicine. 2011. Design Fires in Road Tunnels. Washington, DC: The National Academies Press. doi: 10.17226/14562.
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117 Every tunnel is unique, which makes it very difficult to gen- eralize design fires in road tunnels. On average, based on the survey results conducted for this effort, a fire in each U.S. tunnel occurs 1 or 2 times a year. A number of tunnel fire safety projects, fire tests, and research work that have been initiated around the world in the last 10 years have brought to light a significant amount of information. This helps us to better understand tunnel fires and the safety means to prevent them and to protect tunnels. The most important documented projects are: • FHWA Prevention of Tunnel Highway Fires • TRB/NCHRP Making Transportation Tunnels Safe and Secure • International Technology Scanning Program sponsored by FHWA and others • UPTUN, European Project (EP) • FIT (Fire in Tunnels), EP • DARTS (Durable and Reliable Tunnel Structures), EP • SafeT (a Thematic Network on Tunnels), EP • Safe Tunnel, EP • SIRTAKI, EP • Virtual Fires, EP • EuroTAP, EP • SOLIT, EP • L-surF, EP • EGSISTES, EP. Numerous fire tests were performed or analyzed as part of these projects. The most important are: • The Memorial Tunnel Fire Tests (United States) • Ofenegg tests (Switzerland) • Zwenberg tests (Austria) • PWRI tests (Japan) • Repparfjord tests (Norway) • Benelux tests (the Netherlands) • Runehamar tests (the Netherlands) • Other tests as part of UPTUN project. The full-scale experiments generally provide interesting qualitative observations. For example, some opaque situations appear clearly as a combination of the heat release rate (HRR), the nature of the burning object (smoke density), and the lon- gitudinal air velocity. The relatively low number of experi- ments does not lead to general conclusions. (An exception would be the Memorial Tunnel program because of the large number of tests.) These observations might be used as a ref- erence for more specific research works using appropriate tools (small-scale or numerical models). Table 37 summarizes the benefits for the research, design, and operation of tests and models, with their advantages and disadvantages. • The Memorial Tunnel Fire Ventilation test program pro- duced much empirical data and information for future analysis. It was performed in a real tunnel with geome- try similar to other road tunnels. However, this test was accomplished with fuel pans, which hindered an under- standing of what fire size and fire growth would result from real major tunnel fire events. A number of European tests with real cars, buses, and trucks were performed in tunnels of smaller cross-sectional area. Extrapolation of that data to real tunnel geometry is to be done with care. Because of a lack of full-scale fire tests with real trucks and buses in a real geometry, confirmation of the results of the Runehamar tests is not possible. • There are no regularity requirements in the United States for performing hot smoke tests or burning cars when com- missioning new tunnels. The European experience allows for the verification of fire life safety systems designs, train designers, operators, and first responders. • Small-scale tests and reduced-scale tests are in need of further development. These tests are less expensive and are needed for scientists and designers, because they allow for better understanding of the physics of the process and help verify the computer modeling. Such tests can be repeated in the design at any time and be used for visualization of the smoke behavior in the tunnel depending on the system’s response. • Computational fluid dynamics (CFD) software is con- sidered as the design tool of choice for obtaining an opti- mum design. However, it requires in-depth knowledge of physical processes and numerical models, and prefer- ably experience in testing from the numerical modeler. The strengths and weaknesses of each program are to be investigated beforehand, while validation of the results against experimental data or another equivalent program is encouraged. Good experimental data are required. New small- or large-scale experiments are to be undertaken with the priority objective of validating and calibrating physical models. It may include the understanding of flow generated by fire as well as measurements of some physical smoke properties, which are critical for models CHAPTER FOURTEEN CONCLUSIONS

118 Means Use for: Research Use for: Design Use for: Operation Full-scale Fire Test Programs Advantages: - Direct interpretation - Complete results Disadvantages: - Cost - Limited number of tests Conclusions: - Well suited Advantages: - Direct interpretation - Possibility of using real road vehicles Disadvantages: - Cost - Limited number of tests - Geometry of the test facility Conclusions: - This solution depends on the importance and specific problems of the project (e.g., Memorial Tunnel) Advantages: - Direct interpretation Disadvantages: - Cost - Limited number of tests Conclusions: - Unrealistic if not associated with other objectives Tunnel Fire Tests Before or Under Operation (aimed at optimizing ventilation responses in fire event) Advantages: - Partial results with full-scale facilities - Numerous different situations Disadvantages: - Lack of information due to the limited number of sensors Conclusions: - Useful but partial results Advantages: - Accumulation of experience useful to choose a system - Test performed with real ventilation systems Disadvantages: - Limited number of tests Conclusions: - Useful Advantages: - Shows to the operators how the ventilation reacts - Fire departments are very interested in expected situation Disadvantages: - No operation possible during the tests Conclusions: - Well suited Tunnel Fire Tests Before or Under Operation (aimed at operators and fire department training) Advantages: - Visual observations possible Disadvantages: - Lack of information due to the absence of sensors Conclusions: - Not suited Advantages: - Test performed with real ventilation systems Disadvantages: - Limited analysis due to the lack of measurements Conclusions: - Not well suited Advantages: - Representative situation Disadvantages: - No operation possible during the tests Conclusions: - Well suited Reduced Scale Models Advantages: - Many tests possible - Possible to study global laws governing specific situations Disadvantages: - Needs full-scale reference tests for transposition to real situations Conclusions: - Useful method for research Advantages: - Cost lower than full-scale tests Disadvantages: - Linked to the limitations induced by the similarity laws Conclusions: - Very difficult to conclude that the results are representative of full-scale situations Advantages: - Cost Disadvantages: - Linked to the limitations induced by the similarity laws - No respect of time basis Conclusions: - Possibly unrealistic but demonstrative Numerical Models (CFD) Advantages: - Possible to study many different situations - Information on flow structures unattainable with other methods Disadvantages: - The conclusions must be correlated to existing experimental references Conclusions: - Useful method for research Advantages: - Possible to get an optimization by the use of different assumptions Disadvantages: - The model requires qualification Conclusions: - Useful method for projects, if validated Advantages: - Possible to describe the physical conditions in several locations of the tunnel Disadvantages: - Theoretical results lead to theoretical conclusions Conclusions: - The adaptation depends on the use of the model Source: PIARC (21). TABLE 37 FIRE TESTS AND FIRE MODELING FOR RESEARCHES, DESIGNERS AND OPERATORS

119 (i.e., radiative smoke properties, generation of soot, and turbulence models). Several statements can be made based on the studies, tunnel fire events statistics, experience, and tunnel fire tests: • A tunnel by nature is a highly risky environment. No tun- nel is absolutely safe regardless of how it was designed and what types of fire life safety systems were installed. The goal of the design, operation, and maintenance is to make a tunnel as safe as possible based on previous expe- rience, on present knowledge, and on the development of technical equipment. The key element is prevention of tunnel fire. • Most tunnels experience fires. However, most of the tun- nel events are generally small in scale and involve cars and vans. • Major tunnel fires that involve heavy goods vehicles (HGVs) with dangerous goods and fuel tankers, although rare, can be severe in the tunnel environment. Conse- quences of tunnel fires can be disastrous for occupants, tunnel structures, and the economy. • Severe tunnel fires are rare and happen less often than fires on open roads. Cumulatively, the number of people killed in road tunnels worldwide is fewer than 200, including those killed in collisions. Fewer than 20 tunnels worldwide have suffered substantial structural damages as the result of a fire emergency. • Road tunnel fires cannot be completely eliminated until vehicle fires are eliminated. Analysis of the catastrophic tunnel fire events resulted in the following conclusions: • Fires develop much more quickly than expected. Many known actual tunnel fires and fire curves show a very fast development during the first 5 to 10 (sometimes 15) min. The gradient of temperature is steep and the emission of heat and smoke are very important. • Fire temperatures in excess of 1000°C (1832°F) can be achieved. • Smoke volumes are higher than expected from an early stage of the fire growth. • Fire spread between vehicles occurs over a much greater distance than had been expected previously (e.g., more than 200 m or 656 ft in the Mont Blanc Tunnel). • The road tunnel users behaved unexpectedly, such as: – Did not realize the danger to which they were exposed. – Failed to use the safety infrastructure provided for self-rescue. – Wrongfully believed that they were safer in their cars than if they used the self-rescue safety systems. – Chose to stay in their vehicles during the early stages of a fire because they did not want to leave their property. – Realized too late the danger they had placed them- selves in, by which time it was too late to self-rescue. Safety is a result of the integration of infrastructural mea- sures, operation of the tunnel, and user behavior, as well as preparedness and incident management. The assessment of fire safety in tunnels is a complex issue, where broad multi- disciplinary knowledge and application of different physical models are necessary to explore the causes and development of fires and evaluate measures to prevent and reduce their consequences. A design fire is an idealization of a real fire that might occur. A design fire scenario is the interaction of the design fire with its environment, which includes the impact of the fire on the geometrical features of the tunnel, the ventilation and other fire safety systems in the tunnel, occupants, and other factors. Given the range of variables and human behavior nobody can precisely predict every fire scenario. The key design fire scenarios relevant to fire safety in tunnels are: • For ventilation and other systems (e.g., fixed fire suppres- sions) design and assessment; • For egress analysis; • For thermal action on structures; • For the safety of tunnel fire equipment; and • For work on tunnel construction, refurbishment, repair, and maintenance. A design fire scenario represents a particular combination of events associated with: • Type, size, and location of ignition source; • Type of fuel; • Fuel load density and fuel arrangement; • Type of fire; • Fire growth rate; • Fire’s peak HRR; • Tunnel ventilation system; • External environmental conditions; • Fire suppression; and • Human intervention(s). Design fires in tunnels are usually given as the peak fire HRR, although it has become more common for engineers to combine the peak HRR with the fire growth rate. Some esti- mates of the HRR use weighting of the burning components of a vehicle to incorporate burning efficiency, which implies that the fire may not consume the entire heat load available. The leftover content is typically in the form of either a char residue or as soot and smoke particles displaced by the combustion gas stream. The magnitude and development of fire depends on: • Vehicle combustion load (often called the fuel load) • Source of ignition • Intensity of ignition source • Distribution of fuel load in the vehicle

120 • Fire propagation rate • Tunnel and its environment. Table 38 summarizes the main design fire variables and provides the ranges for these variables. The table illustrates that time-dependent design fire variables depend on a num- ber of factors to be studied. The table was developed for this effort based on the literature review. New energy carriers can lead to explosions with cata- strophic consequences when there is a fire. Although they do not necessarily mean higher risks, they do represent a new sit- uation and imply new risks. Systems, not only components, need to be tested to study different possible scenarios and to develop models for these scenarios. When the scenarios are described in a representative way, technical safety solutions, mitigation systems, and rescue service tactics can be devel- oped. It is also important to study how the different systems (detection, ventilation, mitigation) interact and how the mod- els developed are altered depending on the scenario. The field of new energy carriers is very diverse and constitutes many different fields of research. More research is needed concern- ing how safety in tunnels is affected by the introduction and development of new energy carriers. Fires can develop inside vehicles or outside in a cargo con- tainer. As fires develop inside a vehicle heat builds up, leading to elevated gas temperatures within the enclosure. The ele- vated temperatures will in turn have a significant impact on the growth rate of the fire. Elevated gas temperatures will pre-heat materials that have not been ignited and potentially accelerate flame spread. Gas temperatures in an enclosure can be affected by the size of the enclosure, the ventilation into the enclosure, and the fire HRR. The development of fires inside vehicles depends on a num- ber of factors including: • Fire performance of interior materials and features, • Fire performance of vehicle cargo, • Size and location of the initiating fire event or ignition scenario, • Size of the enclosure where the fire is located, and • Ventilation into the enclosure. Specification of a design fire may include the following phases: • The Incipient Phase is characterized by the initiating source, such as smoldering or flaming fire. • The Growth Phase is the period of propagation spread, potentially leading to flashover or full fuel involvement. • The Fully Developed Phase is the nominally steady ven- tilation or fuel-controlled burning. • The Decay Phase is the period of declining fire severity. • The Extinction Phase is the point at which no more heat energy is being released. Simple heat transfer equations do not allow for the making of a direct correlation between the time–temperature curve and the time–heat release curve. It appears that the known fire growth rates follow the super fast (highest increasing rate mea- sured) temperature rise in the time–temperature curves. How- ever, ultrafast HRR curves are often allowed for the design. Tunnel ventilation systems are still the primary tunnel fire life safety system for controlling smoke and providing a tenable environment for evacuation. There are many types of tunnel ventilation systems. Time Dependent Design Fire Variables Values Range Design fire variables are a function of: Fire Size—Maximum FHRR (1.5 MW–300 MW) Type of vehicle (cars, buses, HGVs, tankers; alternative fuel) Fire Growth Rate (slow, medium, fast, ultra fast) 0.002–0.178 kW/s2 as high as 0.331 kW/s2 measured at one test Type of cargo including bulk transport of fuel Fire Decay Rate 0.042–0.06 (min-1) Fire detection system and delay in activation of FLS systems Perimeter of Fire Car—truck perimeter Ventilation profile Maximum Gas Temperature at Ceiling 110ºC–1350ºC (212ºF–2462ºF) (higher with FCV) Fire suppression system yrtemoeglennuTsyad2–nim01noitaruDeriF Smoke and Toxic Species Production Rate 20–300 m3 ssorc,thgieh,htdiwlennut-ces/ section, length Radiation From 0.25 to 0.4 of total heat flux up to 5,125 W/m2 (1,625 Btu/hr/ft2) - volume (available oxygen) edarg,lennutfoepahs-htgneLemalF - location of exits Tunnel drainage system TABLE 38 MAIN DESIGN FIRE VARIABLES

121 • Although longitudinal ventilation controls smoke, it may increase the fire HRR and fire growth rate once air veloc- ities are high. It may also increase the flame length and help the fire to spread farther. However, recent fire tests concluded that the affect of longitudinal ventilation on fire growth and fire HRR was previously significantly overestimated. • A single-point extraction system supported by jet fans (or other longitudinal ventilation, such as Saccardo noz- zles) is considered the most effective in smoke control for bi-directional traffic tunnels or when vehicles are trapped on both sides of the fire. This system relies on smoke stratification and smoke capture, produces low longitudinal air velocities, and does not impact the fire growth and HRR as much. However, this system is com- plicated and requires air velocity controls on both sides of the fire. It also needs coordination with sprinkler sys- tem activation. Additional means for providing protec- tion of ventilation ducts, such as sprinkler protection of vent duct, may be needed to avoid structural collapse. Ventilation has an influence on the fire development that does not always conform to expectations: • Owing to increased ventilation the fire development for a car can be slowed if the fire is ignited at the front of the car. This is in contrast to the accepted view of supposed accelerated development resulting from ventilation. • The influence of increased ventilation on the observed fire behavior depends on the ignition location. Note that 95% of fires begin in the engine compartment (i.e., at the front). • Under the influence of a high-ventilation velocity, the fire development accelerates for a covered load at a rate 2 to 3 times faster. The fire size was 20% to 50% higher owing to a high-ventilation speed. • There could be a negative effect of ventilation because forced ventilation may cause significant flame deflec- tion, which leads to the chance that the fire might spread to other vehicles and threaten the integrity of the tunnel structure on a larger surface, assuming the ventilation cooling effect and reduction in radiation at the source are insignificant. Tenable environment is well-defined by NFPA 502 and other standards. To develop a time-of-tenability curve, the project must develop: • A fire heat release curve as a function of time, • A design evacuation (egress) curve as a function of time, and • A design systems response curve as a function of time. A tenability map indicates all time steps and the resulting impact on casualties and tunnel structure. It allows for pre- dicting how long the environment will be tenable in the tun- nel and helps to decide what needs to be done to achieve fire life safety goals. A fire suppression industry offers to control the fire size, reducing the maximum HRR and fire growth by applying a fixed fire suppression system. Once a fire is detected early by a reliable fire-detection system, the fire protection system could be activated within several minutes, taking the fire under control and not allowing it to grow further or spread to other vehicles. It may also suppress a small fire. • It is essential that the detection system be capable of detecting a small fire (in the order of 1–5 MW). If this is not achieved and the fire is not detected until it enters its rapid growth phase, the resultant fire will, in all likelihood, be well beyond the capabilities of a fixed fire suppression system. The fire may continue grow- ing, resulting in the production of dangerous steam and may cause concrete spalling. Sprinklers must not be turned off before the fire is completely extinguished or being suppressed by the fire department. Early sprin- kler deactivation may lead to explosions and structural collapse. • Water droplets will be affected by ventilation. Longitu- dinal airflow must be selected to ensure an appropriate droplet spread and mass flow. Ventilation system perfor- mance is also affected by sprinkler operation. The main idea is to acquire a well-designed system with a reliable quick fire-detection system to start these systems before the fire gets too large. • Additional considerations need to be given to the impact of a fixed fire suppression system on smoke stratification, visibility, and steam generation during the evacuation phase. • If the sprinkler system is activated early enough, can ventilation be reduced or eliminated and what will be the impact on smoke production? Additional studies may be required. • There is still a lack of experience in the United States with tunnel fire suppression systems. This system has pros and cons and its benefits need to be evaluated for each tunnel because every tunnel is unique. • A structural protection industry offers coatings and pro- tection materials to protect the tunnel structure from damage. However, what will this do to the safety of the tunnel environment by not allowing heat to dissipate through the tunnel walls? What will happen to the tun- nel temperatures and the ability of first responders to enter the tunnel? Major progress has recently been made in fire-detection technology. Listed and approved video flame and smoke detectors that have been tested in the tunnel environment are now available. Tunnel safety starts with fire detection, which will cause all systems to activate and notify people to evacu- ate. Every second is accounted for in the major tunnel fire event, especially during evacuation and the initial phase of fire development. Several countries provide standard requirements for detection time and maximum fire size for detection.

122 The survey conducted for this effort proved that fires in road tunnels are rare events. Here are some findings and lessons learned from the survey: • More fires occur in the busiest tunnels. In most of the U.S. tunnels, fires happen 1 or 2 times a year; however, most of them are small and do not result in any signifi- cant losses. The most significant fires occur with trucks (HGVs). In these cases, casualties are likely. • Many agencies would consider protection tunnels with the fixed fire suppression system, if proven effective. Future studies are required to address this area of tunnel technology. • Most of the agencies rely on closed circuit television (CCTV) for fire detection and incident detection. This technology needs to be further developed for heat and smoke detection, as well as be tested and listed for fire- detection applications in tunnels. • There is a need to continue developing tunnel ventilation systems and ventilation response in conjunction with other systems such as fixed fire suppression systems. • Specifications for the devices need to be developed fur- ther. Reliable and maintainable devices could become commercially available that are designed for a particular tunnel environment, considering the typical tunnel clean- ing and washing operation, chemicals and pollutants pres- ent, and dirt and debris build up. One example is locating a commercially available pull station system for a road- way tunnel that has long-time reliability. One item for future study that was expressed by many of the national and international tunnel agencies is the need to develop a tunnel fire system computer simulator for opera- tors to manage fires. Similar research programs have been successfully accomplished in Sweden and Austria. Learning from their experience might help tunnel operators, first respon- ders, and tunnel agencies to better understand their tunnels and train their personal accordingly. Many research works and studies have been done in the United States and worldwide on the development of design for tunnel fires. However, there are still knowledge gaps in many areas including: 1. Training and education • Training of tunnel operators and first responders by developing, for example, a virtual fire/systems simulator. • Better understanding of the human behavior of tun- nel users and operators, as well as providing a means of public education. During emergency situations, human behavior is even harder to predict, as the stress of the situation replaces intellect with curiosity, fear, or even panic. Unfortunately, in general, people are inclined to do the wrong thing in the event of a tun- nel fire, such as staying inside their cars instead of heading for the emergency exits. Tunnel emergency management scenarios and procedures must take human behavior into account to be fully effective in saving lives. 2. Operation and commissioning • International practice of commissioning tunnel fire life safety equipment and fire fighting procedures using hot smoke tests and burning actual vehicles in the tunnels needs to be evaluated for future national standards’ considerations. The best international prac- tice of commissioning tunnel life safety systems using hot smoke tests is not (or seldom) used in national practice. With the exception of several juris- dictions, cold smoke is commonly used to evaluate ventilation system performance simulating tunnel fires. Unfortunately, cold smoke tests cannot replace hot smoke tests. The national standards do not require that systems commissioning hot smoke tests use hot smoke tests. • It is advisable to study the experience of the road tunnel operations managing fuel tankers and other dangerous goods. Such experience exists and best practice could be studied for both design and opera- tion. Categorically banning dangerous goods from tunnels may create an adverse economic impact. 3. Physics, numerical modeling, and testing: • Correlation between a time–temperature curve and a HRR curve. • The impact of passive fire protection materials on the fire HRR and resultant temperatures in the tunnel environment. • Verifications through the performance of additional vehicle tunnel fire tests with the special aim of mea- suring the production rates for smoke and toxic gases (e.g., CO, CO2, and HCN) and factors related to the light absorption by smoke (e.g., mass optical densi- ties). Full-scale fire tests may need multi-agency sup- port and possibly international collaboration. • Evaluation of the state of the art of numerical fire and evacuation simulations. Capabilities of captur- ing the effects of mitigating measures, such as early or delayed suppression (e.g., water-based, foam, fixed, and mobile), ventilation, insulation, smoke compart- mentation, operator interventions, and so forth, need to be included. • Post-cooling spalling mechanism and structural pro- tection of tunnel walls by means of a fixed fire sup- pression system. This also requires a review of the experiences with the use of fixed fire suppression systems in managing tunnel fires and additional test- ing of the systems. • Harmonization of the design parameters for numer- ical fire and evacuation simulations. • Numerical modeling of sprinkler system impact on flame and fire size needs CFD code development and validation. • Development of uniform methods of assessment and the validation of numerical modeling results.

123 • Coupling of numerical aerodynamic and fire simu- lation with structural calculation methods and even- tually with evacuation models. • Additional studies and analytical modeling is needed on alternative fuel vehicle fires in the tunnel envi- ronment. 4. Development of specifications, regulations, and tech- nology: • Further development of CCTV-based fire-detection technology tested and listed for tunnel applications. • Further development of tunnel ventilation systems, and the ventilation response in conjunction with other systems, such as fixed fire suppression systems. • Regulations and guidance need to provide better con- sideration of the activity of all systems that interact in a tunnel. Integrated approaches shall be applied to tunnel fire safety. • Consideration shall be given for technical innova- tions that allow for more ambitious safety objectives. • Specifications for the tunnel fire life safety devices. Reliable and maintainable devices could become commercially available that are designed for the tun- nel environment, considering the typical tunnel clean- ing and washing operations, chemicals and pollutants present, and dirt and debris build up. 5. Risk of tunnel fires: • It is important that the frequency of tunnel fires be evaluated against their consequences for developing a weighted risk impact. • Risk of fires in combined use tunnels need to be eval- uated and special recommendations be provided on design approach of combined use tunnel fire safety design. • The field of new energy carriers is very diverse and new types of energy carriers are being introduced. The safety of tunnels that allow alternative fuel vehicles might not rely on component tests of such vehicles, but on the testing of entire systems using realistic sce- narios. Such aspects as possible gas detonations with low ventilation require systematic research. Risk to the tunnel structure as the result of alternative energy carriers’ fires requires additional research work.

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TRB’s National Cooperative Highway Research Program (NCHRP) Synthesis 415: Design Fires in Road Tunnels information on the state of the practice of design fires in road tunnels, focusing on tunnel fire dynamics and the means of fire management for design guidance.

Note: On September 20, 2011, the following errata was released related to NCHRP Synthesis 415. The electronic version of the publicaiton was changed to reflect the corrections.

On pages 106 and 107, an incorrect reference was cited. In the final paragraph on page 106, the last sentence should read: One study came to the conclusion that, although some minimum water application rates would achieve a certain objective, a marginally higher rate would not necessarily improve the situation (79). The figure caption for Figure 35 at the bottom of page 107 should read: FIGURE 35 NFPA 13, NFPA 15, and other International Water Application Rates (79).

The added reference is as follows:

79. Harris, K., “Water Application Rates for Fixed Fire Fighting Systems in Road Tunnels,” Proceedings from the Fourth International Symposium on Tunnel Safety and Security, A. Lönnermark and H. Ingason, Eds., Frankfurt am Main, Germany, Mar. 17–19, 2010.

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