BY JARROD M. SERGI
Fighting a fire in a roadway tunnel can be extremely challenging. The design of these tunnel systems does not allow us ease of operations when we encounter a significant fire. If you have roadway tunnels in your response area, it is essential that you spend time looking into the particular challenges that you will face in your jurisdiction. Below, I offer some tips on how to best preplan response to and mitigation of tunnel fire incidents.
The first critical factor in a tunnel fire response is ensuring clear communication with the tunnel officials. Most of these tunnels have a control center where tunnel personnel can monitor traffic flow, control ventilation, and activate fire suppression systems if the tunnel is so equipped (photo 1). If possible, station a fire department representative in this room during an incident to help direct crews and pass along important information.
NFPA 502
Not all tunnels are operated by state agencies. The Virginia Department of Transportation operates only two of the three tunnel systems in the city of Norfolk; the third is operated by a private agency. If a private agency is in control, it will not necessarily be held to the same standard as the tunnels operated by the state. If you have multiple tunnels operated by different entities, find out what each agency will and will not do. National Fire Protection Association (NFPA) 502, Standard for Road Tunnels, Bridges, and Other Limited Access Highways, outlines the recommended practices and design for road tunnels.
Communicating with the tunnel control room while en route will give you the best information. Control room staff will be able to tell you the fire’s location; the traffic conditions; the best way to access the tunnel to begin suppression operations; and whether motorists are abandoning their vehicles in the tunnel, which could lead to potential rescue issues if they are overcome by smoke. If you have the ability and the available resources, enable tunnel personnel to communicate on fire department radio channels to pass along this important information. You can provide them with a fire department radio and instruct them on its use. Conduct daily radio checks with the tunnel to ensure that tunnel personnel are listening and are able to communicate.
Preplanning
Preplanning is another critical factor for successful operations. Conduct walk-throughs of your local tunnels. Often, the tunnel officials will be more than happy to show you around and point out key tunnel features that will help responding units (photo 2). Important items to look for and ask about include the best access for emergency vehicles, the water supply, and ventilation. If you can control these three items initially, you will be working toward a successful operation.
Access. You can plan fire department access before an incident occurs. It may be very easy to get the apparatus down into the tunnel and begin suppression when traffic is light. However, heavy traffic congestion will delay your response and enable the fire to grow (photo 3). If possible, consider dispatching additional units to approach from the opposite end of the tunnel.
Water supply. For water supply, you can use the tunnel’s standpipes; NFPA 502 requires a standpipe be installed every 75 feet. Most tunnel systems will have a dedicated water supply with a fire pump and municipal water. However, these standpipes are exposed to some weather and may not be in the best condition. If conditions allow, the best water supply is one that the fire department brings in from outside the tunnel using a hydrant.
Ventilation. Coordinating ventilation is also critical. Tunnels may use several types of ventilation systems. They may have installed ductwork and vents at the top or sides of the tunnel walls, or they may have individual fans. The fans in photo 4 can move more than 60,000 cubic feet per minute; this particular tunnel has eight fans. It is critical to find out where fans are controlled and to coordinate ventilation and fire suppression. Where you are making access and where occupants are evacuating will determine how the fans will operate and which way they will direct the smoke.
Sprinklers. Another fire protection feature to be aware of is an installed wet sprinkler system. Sprinkler systems in roadway tunnels have remained largely controversial. Multiple studies have concluded that activating water-based systems will cause panic among occupants and impede firefighting efforts by reducing visibility. If your tunnel is equipped with this type of system, become familiar with it.
Fire Research
Heat release rates during accidents may vary inside of a roadway tunnel based on the type of vehicle involved and its contents-e.g., flammable liquids, synthetics, or products made from wood and paper. Vehicles involved in fire can range from a motorcycle to a large commercial trucking vehicle or even a tanker carrying large amounts of fuel.
Experiments conducted in Norway’s Runehamar Tunnel concluded that larger burning vehicles tend to have a high energy output, which is underestimated in designing tunnel fire protection. During these experiments, it was noted that fires in small passenger vehicles will produce five megawatts (MW), buses will produce 20 MW, and heavy goods vehicles will produce between 30 and 100 MW of heat energy. These heat release rates can be significantly increased if the installed ventilation system is used improperly and creates a high velocity of air travel through the tunnel.
In the United States, very little research has been conducted involving design fires in roadway tunnels. Several countries in Europe are on the cutting edge of roadway tunnel fire response, protection, and suppression.
The fundamentals of firefighting regarding suppression rarely change. Of course, you wouldn’t use a house fire approach in a tunnel fire, but you must still achieve the same basic benchmarks. There has been research to identify effective ways to remotely extinguish fires in tunnels. Specialized equipment such as fast-response or quick-attack vehicles with mounted hose and water enables responders to attack fires without sending firefighters directly into the tunnels. Robotics have been experimented with in tunnel fires to keep firefighters away from the seat of the fire.
Collapse Potential
The last major area for concern is the structural integrity of the tunnel after fire extinguishment. One tunnel in Norfolk has no fireproofing covering the walls. This lack of protection in this tunnel and the tunnels in your area may lead to a potential collapse of large pieces of concrete onto firefighters or occupants.
Depending on your state, you may be required to conduct a certain number of tunnel response drills annually. NFPA 502 recommends conducting a multiple-agency exercise once a year to simulate response to a roadway tunnel fire. This is an opportunity to identify pitfalls in the response system and work on ways to improve it. If you are fortunate enough to be involved in the design process of a tunnel, have your fire code enforcement staff make recommendations during this phase. This is your opportunity to recommend fire protection features such as fireproofing on the walls and ventilation system design and develop strategies for fire attack and access.
The key to success at your next tunnel fire operation will be a thorough prefire plan of the road tunnels in your response area, followed up with frequent training. Tunnel fires present a specific set of firefighting challenges. Become familiar with roadway tunnel design and fire protection features and strive to build relationships with other responding agencies. Learn from the drills you conduct, and take all the information gathered through prefire planning to assist you in developing a workable standard operating procedure.
JARROD M. SERGI is a lieutenant with Norfolk (VA) Fire-Rescue, assigned to a ladder company. He recently completed extensive research on response to road tunnel fire incidents for the National Fire Academy’s Executive Fire Officer Program. He has assisted in developing local and regional training programs and is an instructor for the Virginia Department of Fire Programs and with Real Fire Training LLC. He has a bachelor’s degree in fire science from Columbia Southern University and is a fireengineering.com blogger.
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