National Academies Press: OpenBook

Design Fires in Road Tunnels (2011)

Chapter: Chapter Eight - Survey Results

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Suggested Citation:"Chapter Eight - Survey Results." 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 Eight - Survey Results." 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 Eight - Survey Results." 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 Eight - Survey Results." 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 Eight - Survey Results." 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 Eight - Survey Results." 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 Eight - Survey Results." 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 Eight - Survey Results." 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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46 The survey was sent to the states and agencies in the United States that manage tunnels and to international tunnel agen- cies. There are a number of U.S. states where there are no road tunnels; the survey was not sent to those states. Nine U.S. agencies reported on 32 tunnels, which represent approxi- mately 60% of the U.S. agencies that were addressed by the survey. In addition, the survey was distributed to international tunnel agencies to document the best international practice. A total of 15 agencies worldwide reported on 319 tunnels. This is a summary of the data gathered from the 15 agencies that responded to the NCHRP Design Information on Fires in Road Tunnels (Topic 41-05) on-line questionnaire. Some of the agencies reported on each of their tunnels in separate surveys. Most of the agencies combined multiple tunnels into a singular survey response. The nine U.S. tunnel agencies reported on the 32 tunnels cited in Table 9 and the six international agencies reported on the 287 tunnels cited in Table 10. Not all agencies responded to every question. The actual number of responses for each answer, obtained from the survey data, can be found in Appendix C. The first part of Appendix C shows national data, the second part international data. In addition, there may be more choices made then the number of responders for the “please check all that apply” questions. Therefore, the “total” percentages may not add up to 100% for these questions. Open text responses are taken verbatim. FIRE FREQUENCY IN U.S. TUNNELS Fourteen of 29 national tunnels (48%) reported that the annual tunnel vehicle fire incidents number 1 to 2 every year for each tunnel, whereas 11 of 29 tunnels (37%) reported no occur- rence of fire. The Port Authority of New York & New Jersey was the only agency that reported having from 2 to 5 vehicle fire incidents per year, which can be explained by the volume of traffic in the Holland Tunnel. Ten of 19 reporting tunnels (52%) reported that the most severe vehicle fire incidents in their tunnels occurred from a heavy goods truck. No tanker fires happened in these tunnels. Outside the United States, two agencies reported annual vehicle fire incidents to be less than one every year and another two agencies reported it to be from 1 to 2 every year (refer- enced tunnels outside the United States were built as early as 1967 to as recently as 2010). CONSEQUENCES OF FIRE INCIDENTS Nationally, 17 of 20 tunnels (85%) reported having experi- enced minor damages without structural damage after a fire. However, there were two episodes of structural damage that required tunnel closure for an extended period of time; New York City’s Holland Tunnel and Canada’s Lafontaine Tun- nel. Only 2 of 20 U.S. tunnels had minor casualties (non-fatal) as a result of a fire. The two casualties reported in the United States were at the Holland Tunnel and in Eisenhower/Johnson Memorial Tunnel. There was one major casualty reported at the Lafontaine Tunnel. (No details on the nature of the casualties were provided.) SEVERITY OF TUNNEL FIRES In the United States, in most cases the fire department was involved every time in a fire (15 of 17 responses, 90%). The fire department was involved only occasionally with the Col- orado DOT’s Eisenhower/Johnson Memorial Tunnel, which has its own fire truck, and has never been involved with the Pennsylvania DOT’s Stowe Tunnel, which has so far had no fire incidents. Six of 20 respondents reported that an investi- gation was performed almost every time after a fire, whereas 8 agencies responded that an investigation was performed occasionally after a fire, depending on its size. Eight tunnels reported on the estimated maximum fire size, but only one gave an actual numerical answer. The Eisenhower/Johnson Memorial Tunnel (Colorado) provided a fire size of 15–20 MW (51–68 MBtu/hr). The Maryland Transportation Authority’s Fort McHenry Tunnel and Bal- timore Harbor Tunnel reported a “single tractor trailer truck” fire, and five of the six California tunnels reported a “small car fire.” Four tunnels reported on the longest duration of their fires, with the average of 19 min. The longest fire duration reported was in the Eisenhower/Johnson Memorial Tunnel (25 min). The international data show that the fire department is involved every time in the fire fighting (four of five responses). CHAPTER EIGHT SURVEY RESULTS

47 Of the five international agencies responding, three reported that an investigation was performed almost every time after a fire, whereas one responded occasionally, depending on the fire size. The estimated maximum fire size ranged from 1 to 57 MW (3 to 195 MBtu/hr). The longest duration of a fire ranged from 10 min to 120 min (in a Korean tunnel). EXISTING PRACTICE OF FIRE MANAGEMENT IN ROAD TUNNELS Most agencies (13 of 19 U.S. tunnels) have been successful and the rest were partially successful in managing fire events. All 22 of the tunnels reporting have an emergency response plan in place. Most agencies have videotaped incidences of car fires. For all of the national responses, the strengths of the agen- cies’ fire management programs were diverse from equip- ment, to coordination of multiple entities, to surveillance and rapid response. Preparation and planning were the primary strengths. Of the 19 U.S. tunnels that reported on the kind of fire-detection system used (multiple selections allowed), 18 chose closed circuit television (CCTV) incident detection. Of the 20 U.S. tunnels that reported on the kind of fire pro- tection system used, all chose fire extinguishers in the tunnel, whereas almost all (17) use a standpipe system with fire hose emaNlennuTycnegA Virginia DOT Hampton Roads Bridge Tunnel—EBL Hampton Roads Bridge Tunnel—WBL Downtown Tunnel (First)—WBL Downtown Tunnel (First)—EBL NAS Runway #29 Underpass Monitor–Merrimac Memorial Bridge Tunnel Midtown Tunnel Pennsylvania DOT Liberty Tunnel Stowe Tunnel Maryland Transportation Authority Fort McHenry Tunnel Baltimore Harbor Tunnel Oregon DOT Oneonta Cape Creek Elk Creek Toothrock Arch Cape Salt Creek Sunset Knowles Creek Vista Ridge Twin Tunnels Washington State DOT I-90 Mount Baker Ridge Tunnel I-90 Mercer Island Tunnel Port Authority of New York & New Jersey The Holland Tunnel Chesapeake Bay Bridge and Tunnel Authority Thimble Shoals Chesapeake Channel Colorado DOT— Region 1, Maintenance Section 9 Eisenhower/Johnson Memorial Tunnel (2 bores, 1 unit) California Department of Transportation Webster Tube Posey Tube Sunrise On Ramp Caldecott Tunnel Complex #1 Caldecott Tunnel Complex #2 Caldecott Tunnel Complex #3 TABLE 9 LIST OF US TUNNEL AGENCIES THAT RESPONDED TO THE SURVEY

connections (dry or wet). Of the 20 responses that reported on the kind of fire life safety system used, all use tunnel ven- tilation and 9 stated that their tunnel(s) is/are provided with an emergency egress. There is a wide range of communica- tion systems used by rescue personnel and others for fire emergency, the most frequent one being a radio or cell phone (18 of 30 responses). Almost half of the U.S. tunnels reporting (14 of 30) stated that they have tow trucks available for emer- gency response by either owning them or having the services available in-house. Ten tunnels reported that they contract out for tow trucks. Only a few of the international agencies reported on the strengths of their agencies’ fire management programs or barriers or difficulties that were encountered in implement- ing fire management. When asked to explain the strengths of the agency’s fire management program, two of the four responses (both from Korea) noted that they have a manual procedure, that they are skilled with fire drills, and that they receive feedback from design and construction. Australia’s Sydney Harbour Tunnel Company responds with an “imme- diate use of a deluge system if required.” All international agencies reported on the kind of fire-detection system used, where multiple selections were allowed. All seven chose phones, followed by six with CCTV and five with Linear Heat Detection. Of the six that reported on the kind of fire protec- tion system used, all chose fire extinguishers in the tunnel, and five have fire hydrants along the tunnel. Of the seven inter- national agencies that reported on the kind of fire life safety system used, all use tunnel ventilation, followed by six that provide emergency egress. Of the seven international agencies reporting on the communication systems used by rescue per- sonnel and others for fire emergency, two reported using radio repeaters. The rest chose different communication devices, including other types of radios. 48 BEST DESIGN PRACTICE Most of the U.S. agencies responding use NFPA 502, match- ing the FHWA as the most common guidance/standard used by agencies to address the fire design issues for new and retro- fitted tunnels. Designers are usually required to follow the NFPA 502 when agencies specify the design fire size and fire curve. Most of the time (9 of 10), designers implemented only security with no blast analysis. A large majority of the respon- ders (28 of 31) do not have a standard for their agency tunnel design and for fire rating. Many of the responding U.S. tunnel agencies (25 of 31, 80%) consider themselves as the Authority Having Juris- diction. Usually no risk assessment is approached for fire engineering (20 of 30 responses). State police, fire, or local responders have the role of incident commander (17 of 31 responses). More than half (16 of 31) would consider protection of the tunnel with the fixed fire suppression sprinkler system to meet the new NFPA 502 maximum fire HRR requirements, if proven effective. Most of the agencies (29 of 31) have not identi- fied gaps in research and design for tunnel fire safety or fire detection and protection. However, Maryland Transportation Authority’s Fort McHenry Tunnel and Baltimore Harbor Tun- nel reported that commercially available devices/materials to satisfy some code requirements are not reliable or maintainable inside tunnels. These two agencies stated that in eliminating the gaps to improve tunnel fire safety a strategy would be to Consider co-development of specifications (industry standards) for the devices along with the fire-code requirements such that reliable and maintainable devices are commercially available that are designed for the tunnel environment. Consider the typi- cal tunnel cleaning/washing operation, chemicals and pollutants emaNlennuTycnegA Swedish Road Administration Gota Tunnel Vägverket (Sweden) Södra Länken Mak Hungary (Hungary) M6 South Korea Expressway Corporation Average from 280 tunnels (555 tubes) Jookryung Ministère des transports du Québec (Canada) Ville-Marie Lafontaine Sydney Harbour Tunnel Company Sydney Harbour Tunnel TABLE 10 LIST OF INTERNATIONAL TUNNEL AGENCIES THAT RESPONDED TO THE SURVEY

49 present, and dirt/debris build up. (For example, locating a com- mercially available pull station system for the roadway tunnel application that is reliable over a long time period has proven difficult). Many of the U.S. tunnels (22 of 29) would consider a fire event to be similar to a seismic event for design purposes. Most international agencies, four of the seven reporting, have their own standard for tunnel design and for fire rating. All five international respondents stated that the most com- mon guidance/standards used by designers to address the fire design issues for new and retrofitted tunnels were either domestic regulation, European Union, or PIARC. In Canada they use NFPA 502. Four of seven responded that designers are usually given only the fire size, whereas three are provid- ing the fire curve. Two of the six international agencies to respond reported that designers usually implement only secu- rity, followed by two respondents noting that they implement security and blast design. One-half of the international agencies reported that the Authority Having Jurisdiction is usually the fire department. All seven international agencies responding reported apply- ing a risk assessment approach for fire engineering. This is probably the most obvious difference between the U.S. and international approaches. Five of the seven respondents reported having an emergency response plan in place. Of the six international agencies responding on which agency has the role of incident commander, two reported the fire department and two that it is in cooperation with the fire department. Four of six international tunnel agencies reported that they would consider protection of the tunnel with the fixed fire suppression system (sprinkler system) if proven effective. Most of the agencies (four of six) have identified gaps in research and design for tunnel fire safety or fire detec- tion and protection. One area needing improvement, accord- ing to one agency, is “Real world experience in the use of deluge.” Most of the international tunnels (five of six) would not consider a fire event to be similar to a seismic event for design purposes. MAINTENANCE, REPAIR, AND REHABILITATION OF THE FIRE MANAGEMENT SYSTEMS The average tunnel age as given by the 32 U.S. tunnels was approximately 54 years (built around 1956). Most tunnels are under 24 h supervision (21 of 32 tunnels reported). The major- ity of the tunnels reported that the normal traffic operation is uni-directional (28 of 32). Thirty-four percent (11 of these 32) reported that their tunnel operates in bi-directional mode only during construction/maintenance in the other tube and 16 never run in bi-directional mode. Eight U.S. tunnels allow gaso- line tankers to run freely and four tunnels can be used by gasoline tankers when supervised and during special times (schedule or tunnel closing). Twenty-four tunnels responded to what is an acceptable response time for a fire emergency, and answers ranged from 3 to 20 min. All seven VDOT tunnels considered 10 to 15 min acceptable, whereas all nine Oregon DOT tunnels considered 20 min to be an acceptable response time. The lighting and emergency communication systems were often not designed to survive major fire events (17 of 30). One-half of the 30 tunnels reported that they were inclined to actively screen or otherwise monitor truck cargoes entering a tunnel without disrupting the traffic flow as a prevention method. Of the eight that responded with the most common fire or life safety equipment planned for repair or replacement, all responded with tunnel ventilation, standpipes, and communication. The next most common choice was emergency lighting (six responses). The average of the 20 U.S. tunnels that provided a numer- ical life expectancy was 105 years. VDOT noted that for its seven tunnels their “design life is 50 years, however, life expectancy typically exceeds 100 years.” The Chesapeake Bay Bridge and Tunnels stated for both of their tunnels that it “depends on the amount of maintenance performed.” Most U.S. agencies (19 of 31, 61%) reported on the need for additional training tools for operators to manage a fire using tunnel fire/systems simulators. Outside of the United States, and excluding Korea’s “aver- age from 280 tunnels,” the average age is approximately 16 years (built about 1994). All seven international agencies reported that their tunnels are under 24-h supervision. (Please note that there are many unmanned tunnels all over the world and the above number does not reflect all of the existing tun- nels.) Six of the seven international agencies stated that their tunnels run uni-directional during normal traffic operation. Four of the six international tunnels reported that their tunnels never operate in bi-directional mode. The rest normally do operate in bi-directional mode. As for what types of vehicles use the tunnel, five of seven tunnels reported HGVs and four reported gasoline tankers (freely). Internationally, there was a broad spectrum of tunnel life expectancy. Three of the seven tunnels chose 100 years and two chose 50 to 100 years. The other two agencies reported 200 years and 80 years. Two of the six international tunnel agencies reported that 10 to 15 min is an acceptable response time for reaching a fire event. The remaining four reported 2 to 10 min. Five of the six agencies reported that the lighting and emergency com- munications systems were designed to survive major fire events most of the time. Five of the six tunnels do not actively screen or otherwise monitor truck cargoes entering the tunnel without disrupting the traffic flow.

Seventy-two percent of national and international tun- nels are under 24 h supervision, 87% reported that their tun- nels operate uni-directionally, whereas 52% never operate in bi-directional mode, even if there is construction and maintenance in the other, parallel tube. Gasoline tankers are freely allowed in 42% of national and international tunnels, whereas only four allow them to travel with supervision when the tunnel is closed to normal traffic (none of the international tunnels). Fifty-five percent of the national and international tunnels reported that they do not actively screen or otherwise monitor truck cargoes entering the tunnel with- out disrupting the traffic flow, whereas the remaining 45% reported that they do. Sixty percent of the tunnels reporting worldwide noted that they need additional training for operators to manage a fire utilizing tunnel fire and systems simulators. SELECTED IMPORTANT EXAMPLES Among all the tunnels responding, the Port Authority of New York & New Jersey’s The Holland Tunnel, built in 1927, was one of the two tunnels that reported suffering structural dam- age as a result of a fire that required tunnel closure for an extended period of time. It was also one of the two that reported minor casualties. It was the only tunnel reporting two to five vehicle fire incidents per year. The most severe vehicle fire incidents in this tunnel were from a passenger car, a heavy goods truck, vans, and a truck load of magnesium in 1948. In The Holland Tunnel, the fire department is involved every time and investigations have been performed occasionally depending on the fire size. There is no information on its esti- mated maximum fire size or its duration. Continuous training has been suggested. The Holland Tunnel uses pull stations, CCTV, telephones, and linear heat detection in its fire-detection system. The fire protection system in the tunnel involves fire extinguishers, fire hydrants, fire apparatus, and a wet standpipe system with fire hose connections. The fire life safety system involves tun- nel ventilation and an emergency egress. It was reported that periodic hot smoke fire tests are conducted in the tunnel to train the operators and verify system performance. They believed that a tunnel fire/systems simulator would be useful for operators to help manage a fire. Other U.S. tunnels of interest are the Colorado DOT Eisenhower/Johnson Memorial Tunnels, built in 1973 and 1979, respectively. Although it only had minor damages (no structural damage), it was one of the two that reported minor casualties. It reports having one to two vehicle fire incidents per year. The most severe vehicle fire incidents in this tun- nel were from recreational vehicles and motor homes. The fire department is involved occasionally for both tunnels and investigations have been performed every time. The esti- mated maximum fire size was 15–20 MW (51–68 MBtu/hr) 50 and the longest duration was 25 min. The Eisenhower/Johnson Memorial Tunnels reported one barrier or difficulty encoun- tered when implementing fire management, where there were technical issues regarding minimal emphasis on training. The tunnels use only CCTV for its incidence (fire) detection system. The fire protection system in the tunnel involves fire extinguishers, fire hydrants, and a fire apparatus. The fire life safety system involves tunnel ventilation and an emergency egress. They believed that a tunnel fire/system simulator would be needed for operators to help manage a fire. Among the international examples selected were Québec’s Ville-Marie & Lafontaine Tunnels, built in 1976 and 1967, respectively, and the tunnels combined their responses. The fire incident occurred in the Lafontaine Tunnel in 1982. This tunnel fire was caused by a heavy goods truck and there was one fatality. Structural damage in the Lafontaine Tun- nel required tunnel closure for an extended period of time (about 2 months). The combined data for the Ville-Marie & Lafontaine Tunnels noted one to two vehicle fire incidents per year. The most severe vehicle fire incidents were from heavy goods trucks. The fire department was involved every time and investigations were done occasionally, depending on the fire size. The estimated maximum fire size was 20 MW (68 MBtu/hr) and the longest duration was 30 min. The tun- nels use telephones, video surveillance technology, and 911 for its fire-detection system. The fire protection system in the tunnel involves fire extinguishers and fire hydrants. The fire life safety system involves tunnel ventilation and emergency egress. They believed that a tunnel fire/system simulator would be needed for operators to help manage a fire. Australia’s Sydney Harbour Tunnel, built in 1992 with a life expectancy more than 100 years, is protected by a fixed fire suppression system. For fire detection, this tunnel uses CCTV, telephones, heat detection (other than linear), tunnel smoke detection, and video surveillance technology. For fire protection, this tunnel uses fire extinguishers and fire hydrants in the tunnel; a fire sprinkler system, a fire apparatus, and foam are stored in the tunnel. For fire life safety, this tunnel uses tunnel ventilation, an emergency egress, and an egress pressurization system. A waterscreen displaying a 7 × 4.5 m (23 × 14.8 ft) stop sign is used to minimize or eliminate prob- lems such as congestion and traffic management during a fire. Cars, buses, trucks, and HGVs use this tunnel, and there is an average of less than one vehicle fire incident each year. The fire department is occasionally involved in fire fighting and there is an investigation after each fire. A passenger car fire was considered to be the most severe vehicle fire inci- dent. A deluge sprinkler was used in managing the fire event. Although this incident caused no damage to the tun- nel, it was closed for operation for more than 30 min. There were no casualties. The estimated maximum fire size was 3 MW (10 MBtu/hr) and lasted 10 min. There are various exercises and other training provided to staff and first respon- ders to ensure proficiency in response to an incident. They

51 “burn cars in the tunnel to demonstrate the smoke, heat and noise to our operators. This also enables the deluge and ven- tilation to be proven. All operators have to complete task books on a regular basis.” Tunnels and emergency response equipment are inspected and tested every 6 months. The operational protocols for the use of the ventilation system during a fire event are “preprogrammed for a single fire, multiple fire and congested tunnel.” FINDINGS AND FUTURE STUDIES Responses were received from 15 agencies representing 319 tunnels worldwide. Nine U.S. agencies reported on a total of 32 tunnels, whereas 6 international agencies reported on a total of 287 tunnels worldwide (280 from Korea’s average). The questionnaire proved that fires in road tunnels are rather rare events, with a greater number of fires occurring in the busiest tunnels. In most of the U.S. tunnels, fires happen one or two times a year; however, most of them are small and do not result in any significant issues. The most signifi- cant fires occur with trucks (HGVs). In these cases, casualties are likely. In 1948, the Holland Tunnel in New York and the Lafontaine Tunnel in Canada experienced structural damage after a fire and had to close for an extended period of time. Other tunnels have never experienced structural damages and/or lengthy closures. The maximum estimated fire HRR was reported at 57 MW (195 MBtu/hr). Typically, fire depart- ments are involved in serious fire events and investigations follow most of the time. Based on the responses received to our survey, it takes about 30 min to extinguish a severe tunnel fire; however, the longest reported event lasted for 120 min. Most of the tunnels are equipped with CCTV cameras and have videotapes of fire incidents. Almost all of the tunnels have an emergency response plan. Most of the U.S. agencies and some international agencies rely on NFPA 502 for tunnel safety design. International agen- cies also use PIARC, the European Union, and other docu- ments for guidance. Several international agencies provide the designers with fire curves along with the fire size. All seven of the international agencies apply a risk assessment approach for fire engineering, whereas only 10 of the 30 U.S. tunnels reported applying a similar approach. Most of the national and international agencies responded that they would consider a fixed fire suppression system to meet the new NFPA 502 Max Fire HRR Requirements, if proven effective. Some stated that they are looking for real-world experience in the use of a deluge system. More than 60% of the tunnel agencies reporting world- wide expressed their interest in additional training tools for operators to manage fires using a tunnel fire systems simulator. One recommendation that came from most of national and international responders is the need to develop computer- based training tools for operators to manage fires using a tunnel fire systems simulator. Preparations and planning and emphasis on training are considered to be the most impor- tant. This is one of the areas that require future studies and development. Fire drills and having feedback from design and construction are considered the strength of the agency’s fire management programs. Another lesson learned is that many agencies (55% of those responding worldwide) would consider protecting tunnels with the fixed fire suppression system (sprinkler system) if proven effective. Future studies are required to address this area of technology for tunnels. Most of the agencies rely on CCTV for fire detection and incident detection. This technology needs to be further devel- oped for heat and smoke detection, as well as be tested and listed for tunnel fire-detection applications. All responders rely on tunnel ventilation systems for heat and smoke control. There is a need to continue developing such ventilation systems and ventilation response in conjunc- tion with other systems such as fixed fire suppression systems. Specifications are needed for the devices that require fur- ther development. Reliable and maintainable devices could become commercially available that are designed for the tunnel environment, considering the typical tunnel cleaning/ washing operations, chemicals and pollutants present, and dirt and debris build-up. One example is locating a commercially available pull station system for a roadway tunnel that has long-time reliability. Although many U.S. agencies prohibit gasoline tankers from entering tunnels freely (8 of 32 tunnels allow them), they are allowed freely in most of the international tunnels. Four U.S. tunnels allow gasoline tankers to travel through while supervised and when the tunnel is closed to normal traffic. Their experience may need further study. Although most U.S. tunnels are uni-directional, many would consider using them as bi-directional during construction or maintenance in the parallel tube. Thus, bi-directional mode is considered for fire design for most uni-directional tunnels. COMPUTER-BASED TRAINING TOOLS FOR OPERATORS TO MANAGE FIRE— VIRTUAL TRAINING Survey results demonstrated the need for computer-based train- ing tools. The training of emergency service personnel and tunnel operators is an important aspect in ensuring the safety of tunnels. Often, such training is hampered by the limited training opportunities. For the training of firefighters, tunnels either have to be temporarily closed or special underground

facilities have to be used. Also, there is the additional environ- mental issue of making fires, which are generated by burning cars or by pan fires. Finally, such exercises may damage or dirty the tunnel. Virtual training offers a user-friendly and clean alternative. In a virtual training tunnel, fire and smoke only exist in computer memory. Virtual exercises have many advan- tages, including that they: • May be repeated as often as necessary, • Do not require the closure of tunnels, and • Do not cause pollution. The VIRTUALFIRES simulator has been developed within a European project and allows the user to visualize the fire and smoke development and the transport of heat and toxic combustion products inside a tunnel and then move through the virtual space in the same way as through a real, physical tunnel (13). The simulator uses and accesses a database, which contains the results of 3D transient combustion (CFD) simulations for particular tunnel geometries with associated safety installations, particular fire hazard scenarios, and so forth. The CFD results can be displayed using a personal computer and a head-mounted display. Two systems have been developed. The first where the CFD simulation is pre-calculated, stored in a database, and then displayed. The other’s calculations are carried out in parallel to the visualization. In the first system, the user will be able to move through the data, but will not be able to change the characteristics of the simulation such as the ventilation characteristics in real time. In the second sys- tem, the user may change the properties of the simulation while the data are displayed and observe a real-time effect of the changes. The VIRTUALFIRES simulator can be used for assessing the fire safety of tunnels, for the training of rescue personnel, and for planning rescue scenarios, and will be able to supple- ment real fire tests. The end users of this system are rescue organizations such as fire departments, tunnel operators, and government organizations interested in tunnel safety. The sys- tem can be used for making an objective assessment of the fire safety of existing tunnels. It can also be used for educating drivers on how to behave in case of a fire emergency in a tun- nel and what to expect. The VIRTUALFIRES system is able to handle tunnels of any cross section with a variety of installations, including: • Fans; • Ventilation inlets and outlets; • Fire extinguishing nozzles; • Escape compartments, exits, lights etc.; and • Cars, trucks, or rolling stock. The data describing the shape of the tunnel cross section as well as the fixed installations are provided in a suitable for- 52 mat (AUTOCAD) and are used to generate the grid for the transient combustion calculation. The user may: • Define a scenario and replay this scenario using the for- ward/stop/rewind/start buttons on the graphic user interface. • During a concurrent session, the user may switch on/off existing fans, fire extinguishers, and restart a session. The following can be visualized: • Smoke (using output from the CFD software) to check visibility. • Iso-surfaces of temperature to check survivability. • Streamlines allowing for visualization of the efficiency of the ventilation system. One of the goals of a project was to achieve real-time CFD calculations so that users may immediately see the effects from changes, such as from switching on/off fans and from activating fire extinguishers. The calculated dataset consists of different ventilation sce- narios for the Mt. Blanc Tunnel in France and the Gleinalm Tunnel in Austria. Both tunnels were examined with their for- mer ventilation systems and also with the improved ventila- tion systems after reopening. Another tunnel simulator was developed in Sweden and has been in operation since the summer of 2004. It is an important instrument for creating realistic conditions to help train operators to better handle fire situations. With this sim- ulator, the Swedish Road Administration can maintain a high level of staff competence without causing disruptions in traf- fic that usually result from major exercises in tunnels. One of the major goals is to provide the training in a useful and cost- effective way. The simulator is also used to evaluate existing routines and checklists for the Göteborg tunnels. Through the simula- tor, errors and weak spots in the routines can be found before they have an actual impact in the real world (see Figure 13). New tunnel simulators can also be developed and tested on the design stage before they are introduced into the traffic environment, so that operators will be well prepared when a new tunnel opens. In Sweden, all future tunnel projects will require a tunnel management application utilizing the simu- lator. The simulated tunnel environment was in use for two months before the opening of Göteborg’s latest tunnel, the Göta Tunnel. This gave the traffic managers ample time to acquire experience with the new system before the opening. With periodic updates on various situations, they are better prepared when an incident occurs. Groups of operators from various tunnels gather after training sessions to discuss the

53 taught scenario. In this way they can learn from each other. The simulator is also used for training new operators; it helps to familiarize them with how the tunnel monitoring applica- tion works before they work on a real one. The simulator can also be extremely beneficial for existing tunnels. In the simulator, the tunnel and its vicinity are modeled using a 3D modeling tool, creating a virtual version of the tun- nel. The model is then filled with vehicles. Despite its com- plexity, the tunnel simulator can be run on a regular computer, without the need for upgraded hardware. The detailed graph- ics are created using normal graphic cards and an industry standard 3D graphics engine. The VIRTUAL FIRE project, discussed earlier, was devel- oped as a computer-based training tool. It is important to estab- lish a similar program for the United States and to incorporate this tool into the U.S. standards.FIGURE 13 New tunnel simulators.

Next: Chapter Nine - Design for Tunnel Fires Literature Review »
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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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