Abstract:
Tunnel fire protection system for isolating and suppressing fires in a tunnel includes a fire detecting arrangement arranged in the tunnel for detecting a fire, curtain assemblies spaced apart from one another in an axial direction of the tunnel to partition it into zones and a control unit coupled to the fire detecting arrangement and the curtain assemblies for directing the release of curtains from the curtain assemblies based on the detection of a fire. In this manner, a tunnel fire can be isolated in a zone between a pair of barriers formed by the curtains upon their release. To suppress the fire, fire extinguisher units are arranged on the tunnel walls, with at least one in each zone, and those in the zone in which the fire is detected are activated by the control unit. The fire extinguisher units may be aerosol-type fire extinguishers.

Description:
CROSS-REFERENCE TO RELATED APPLICATION  
       [0001]     This application claims priority under 35 U.S.C. 119(e) of U.S. provisional patent application Ser. No. 60/710,644 filed Aug. 22, 2005, which is incorporated by reference herein. 
     
    
     FIELD OF THE INVENTION  
       [0002]     The present invention relates to a fire protection system for tunnels and a system and method for detecting and reacting to a fire in a tunnel to minimize loss of life and expedite extinguishing of the fire.  
         [0003]     The present invention also relates to a method for isolating a fire in tunnel and a method for detecting the location of a fire in a tunnel.  
       BACKGROUND OF THE INVENTION  
       [0004]     Of all different types of fires, tunnel fires likely have the greatest potential for significant loss of life in view of several factors unique to tunnels. These factors include the inherent confining area of the tunnel which increases the intensity of the fire, the lack of natural ventilation in the tunnel to disperse smoke, gases and heat generated by the fire, the restricted egress from the tunnel for people trapped by the fire, and people&#39;s unfamiliarity with the presence and location of emergency exits in the tunnel, if any. Indeed, in view of construction and cost factors, there are often an insufficient number of emergency exits in a tunnel to allow for egress of a typical number of people trapped in the tunnel by a fire.  
         [0005]     One common scenario which gives rise to an extremely dangerous tunnel fire is when a single vehicle, a car or truck, catches fire inside the tunnel, possibly by crashing into a tunnel wall or into another vehicle. This single vehicle may block traffic through the tunnel in one or both directions requiring other vehicles to stop inside the tunnel. Some of these stopped vehicles may be in close proximity to the vehicle on fire and may also catch fire as the fire in the original vehicle spreads, e.g., flaming parts of the original vehicle may contact these stopped vehicles and ignite them or fuel may spill from the original vehicle causing the stopped vehicles&#39; fuel tanks to explode. This would create a chain reaction of fires and explosions inside the tunnel which would be significantly more severe than the original vehicular accident.  
         [0006]     Another problem prevalent in tunnel fires is that the fires generated by burning vehicles produce dense clouds of smoke and harmful gases because the flammable material in the vehicles includes, inter alia, fuel, oil, tires, rubber and synthetic materials. Moreover, since these materials may burn at a temperature as high as 1400° F., an excessive amount of heat is generated in the tunnel. The smoke, gases and heat make it difficult for the people exiting from vehicles stopped in the tunnel to breathe and to find their way to emergency exits.  
         [0007]     Still another problem of a tunnel fire is that it is often difficult for first responders, e.g., fire department personnel, to reach the site of the original fire or subsequently generated fires in a timely manner in order to begin extinguishing the fires. Unfortunately, the fire personnel must often exit their vehicles close to an entrance to the tunnel in view of the presence of stopped vehicles between the tunnel entrance and the site of the fires and people exiting the tunnel to escape from the fire. The fire personnel must therefore carry portable firefighting equipment into the tunnel to the site of the fires in order to be able to begin to fight the fires. This delay further increases the likelihood of the loss of life of people trapped in the tunnel.  
         [0008]     Another possible problem arises if the tunnel fire is not extinguished quickly enough. In this case, the tunnel may suffer structural damage which may further complicate efforts to reach and extinguish the fire.  
       OBJECTS AND SUMMARY OF THE INVENTION  
       [0009]     It is an object of the present invention to provide a new and improved fire protection system for tunnels which detects a fire in the tunnel, isolates the fire and thereafter attempts to suppress the fire.  
         [0010]     It is another object of the present invention to provide a new and improved method for detecting the location of a fire in a tunnel and preferably thereafter isolating the fire.  
         [0011]     It is yet another object of the present invention to provide a new and improved system and method for detecting and reacting to a fire in a tunnel to minimize loss of life and expedite extinguishing of the fire. The reaction may be a variable real-time reaction which depends on the detected location of the fire.  
         [0012]     In order to achieve these objects and others, a tunnel fire protection system in accordance with the invention includes a fire detecting arrangement arranged in the tunnel for detecting a fire in the tunnel, a plurality of curtain assemblies spaced apart from one another in an axial direction of the tunnel and each including a releasable curtain arranged to drop toward a bottom of the tunnel, and a control unit coupled to the fire detecting arrangement and the curtain assemblies for directing the release of the curtains based on the detection of a fire. By means of the invention, a tunnel fire can be isolated in a “zone” between a pair of barriers formed by the curtains upon their release. That is, the curtains immediately before and after the fire are released to thereby trap and contain the fire between the curtains. Therefore, the fire cannot spread beyond the curtains to other zones in the tunnel.  
         [0013]     Moreover, to begin suppressing the fire, fire extinguisher units are arranged on the tunnel walls, with at least one being in each zone. The fire extinguisher units are activated by the control unit upon detection of a fire, and specifically, only those fire extinguisher units in the zone in which the fire is detected are activated. The fire extinguisher units may comprise one or more fire extinguishers, for example, aerosol-type fire extinguishers.  
         [0014]     Each curtain assembly includes weighted ceramic curtains in a folded or compacted form and, after being released, laterally overlap one another across substantially the entire width of the tunnel to thereby form the barrier. The curtains preferably have a length so that they extend proximate to or in contact with the bottom of the tunnel.  
         [0015]     The fire detecting arrangement includes smoke detectors, thermal detectors and infrared cameras or other sensors which are capable of detecting either a fire or a condition resulting from the fire, e.g., heat, combustion gases or smoke.  
         [0016]     Enhancements to the fire protection system include the mounting of speakers in the tunnel to enable messages relating to responses to the fire to be provided to people in the tunnel upon detection of a fire, and strobe lights in the tunnel which are activated upon detection of a fire.  
         [0017]     In a method for detecting and reacting to a fire in a tunnel in accordance with the invention, fire extinguishers and curtain assemblies are arranged at multiple locations along substantially the entire length of the tunnel. Upon detecting the location of the fire in the tunnel, specific fire extinguishers are activated based on the detected location of the fire and the curtains of one or more of the curtain assemblies is/are released based on the detected location of the fire.  
         [0018]     As to the determination as to which curtains to release, the tunnel can be partitioned by the curtain assemblies into zones, each formed between a pair of curtain assemblies, so that only those curtain assemblies which define the zone in which the fire is detected, i.e., the curtain assembly immediately before the fire and the curtain assembly immediately after the fire, are directed to release their curtains. In a similar manner, only those fire extinguishers which generate fire suppression agent in the zone in which the fire is located are activated. This eliminates unnecessary curtain deployment and fire extinguisher activation.  
         [0019]     Variations in the method in order to aid evacuation of people from the tunnel and/or fire and rescue personnel to perform rescue and fire-fighting operations include arranging speakers and strobe lights at multiple locations in the tunnel and generating audio messages via the speakers relating to desired actions by people in the tunnel and activating the strobe lights upon detection of a fire.  
         [0020]     The location of the fire can be detected by sensors at multiple locations along the axial length of the tunnel, the sensors being of the type described above. The location of each sensor is associated with its identification such that upon generation of a signal from the sensor indicative of a fire or fire condition, an approximate location of the fire is determinable since the location of the sensor generating the signal is known.  
         [0021]     Alternatively, to allow for automatic deployment of the fire extinguishers, a fire-detecting or fire-condition detecting sensor may be arranged in connection with each fire extinguisher which would then be automatically activated whenever the associated fire-detecting or fire-condition detecting sensor detects a fire or fire condition.  
         [0022]     A method for isolating a fire in a tunnel in accordance with the invention includes arranging curtain assemblies at multiple locations in the tunnel, each curtain assembly being as described above, and releasing the curtains from at least one curtain assembly based on the detected location of the fire. The curtain assemblies can be spaced apart from one another to form zones in the tunnel between each adjacent pair of curtain assemblies, in which case, the curtains are released from the curtain assemblies defining the zone in which the fire is detected. In this regard, the extreme zones, i.e., the zone at each end of the tunnel, may be defined by only a single curtain assembly with the other end of the zone being an entrance to the tunnel. The fire can be detected by the various sensors mentioned above.  
         [0023]     A method for detecting the location of a fire in a tunnel in accordance with the invention includes partitioning the tunnel into a plurality of axial zones, arranging fire-detecting or fire-condition detecting sensors at multiple locations along the axial length of the tunnel such that at least one sensor is arranged in each zone, and associating the zone in which each sensor is located with its identification such that upon generation of a signal from the sensor indicative of a fire, the zone of the sensor is known and thus an approximate location of the fire is determinable. 
     
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0024]     The invention, together with further objects and advantages thereof, may best be understood by reference to the following description taken in conjunction with the accompanying drawings, wherein like reference numerals identify like elements, and wherein:  
         [0025]      FIG. 1  is a cross-sectional view of a tunnel showing part of the tunnel fire protection system in accordance with the invention.  
         [0026]      FIG. 2  is a cross-sectional view of the tunnel taken along the line  2 - 2  of  FIG. 1 .  
         [0027]      FIG. 3  is a schematic showing major components of a tunnel fire protection system in accordance with the invention.  
         [0028]      FIG. 4  shows is a cross-section view of an example of a fire extinguishing unit used in the invention. 
     
    
     DETAILED DESCRIPTION OF THE INVENTION  
       [0029]     Referring to the accompanying drawings wherein like reference numerals refer to the same or similar elements,  FIG. 1  shows a transverse cross-section of a tunnel  10  in which the fire protection system  12  in accordance with the invention is installed. One of the primary objectives of the tunnel fire protection system  12  is to isolate or confine a fire in the tunnel  10  by creating a barrier to the spread of the fire and smoke, heat and gases generated thereby. To this end, a series of curtain assemblies  14  are placed in the tunnel  10  at different axial locations.  
         [0030]     A tunnel zone is defined between each adjacent pair of curtain assemblies  14 , as well as between the ends of the tunnel  10  and the curtain assemblies at the extreme ends of the tunnel  10 . The designation of such zones is used to detect the location of a fire for the purpose of determining an optimal reaction to the fire.  
         [0031]     As shown in  FIG. 1 , each curtain assembly  14  is mounted to a ceiling  16  of the tunnel  10 , which may be an upper part of the tunnel wall  18 . Each curtain assembly  14  includes weighted ceramic curtains  20 , each in a folded or compacted form in a pre-release state. The curtains  20  are arranged such that their lateral edges overlap one another after they are released, and have a predetermined length so that they extend close to or possibly in contact with the bottom of the tunnel  10  after full expansion (in  FIG. 1 , two curtains  20  on the right side are shown in a release state). The overlapping curtains  20  form a barrier at an axial location of the tunnel  10  which inhibits smoke, heat and gas from passing therethrough.  
         [0032]     Curtains  20  are maintained in their folded or compact form in each curtain assembly  14  until the presence of a fire is detected. Upon detection of a fire, the curtains  20  from the curtain assemblies  14  immediately in front of and immediately behind the axial location of the tunnel  1 —at which the fire is detected are released and would then drop, in view of their weighting, to the bottom of the tunnel  10  to isolate or confine the fire between the released curtains  20 . Thus, if the fire is detected at a location immediately in front of a curtain assembly  14 , upon release of the curtains  20 , people in an area of the tunnel  10  behind the curtain assembly  14  will not be encumbered by the fire and the smoke, heat and gases being generated thereby. These people should therefore be able to locate emergency exits and exit safely from the tunnel  10 .  
         [0033]     Release of the curtains  20  can be performed in various ways, for example, electronically by means of a control unit  22 , discussed in detail below with reference to  FIG. 3 .  
         [0034]     Each curtain assembly  14  includes optional housings  24 , each containing a single curtain  20 . Housings  24  are mounted to the ceiling  16  of the tunnel wall  18  at a plurality of location along the axial length of the tunnel  10 . Housing  24  protect the curtains  20  from damage that might be caused by the environment in the tunnel  10 . To enable release of the curtains  20  from the housings  24 , housings  24  are provided with a deployment door which is released upon receipt of a command signal from the control unit  22  indicating that a fire is present in a tunnel segment immediately in front of or immediately behind the location at which the curtain assembly  14  is located.  
         [0035]     The spacing between the curtain assemblies  14  can be selected as desired by the protection system designer, e.g., 50 feet or 100 feet. The width of the curtains  16 , and thus the optional housings  24  therefor, can be selected as desired and in one possible construction, the curtains  20  each have a width of about 3 feet.  
         [0036]     Referring now to  FIGS. 2 and 3 , the fire protection system  12  includes sensors  26 ,  28 ,  30  which detect the presence and location of a fire in the tunnel, or conditions indicative of a fire, e.g., smoke, heat or specific combustion gases. These sensors  26 ,  28 ,  30  are mounted to the tunnel wall  18  or stationary supports in the tunnel  10  at various locations in the tunnel  10 . Each type of sensor may be substantially equally spaced along the tunnel  10 , e.g., every 100 feet or so.  
         [0037]     A first type of sensor  26  is a smoke detector which detects smoke. A second type of sensor  28  is a thermal detector which detects heat. A third type of sensor  30  is an infrared camera which detects infrared radiation which can be analyzed to determine the presence of a fire. Sensors  30  may be closed circuit television cameras. Additional types of fire-detecting or fire condition detecting sensors, which detect or provide data which can be analyzed to detect a fire or detect or provide data which can be analyzed to detect conditions of a fire such as smoke, heat and combustion gases, can be used in the system  12 .  
         [0038]     Sensors  26 ,  28 ,  30  are coupled to a control unit  22 , e.g., through a wired connection along or in the tunnel wall  18  or wirelessly. Control unit  22  receives signals from the sensors  26 ,  28 ,  30  indicative of a fire, smoke, heat or combustion gases, or data from the sensors  26 , 28 ,  30  which is analyzed by software in a memory of the control unit  22  to determine the presence of a fire or smoke, heat or combustion gases indicative of a fire. Control unit  22  thus determines the existence of a fire in the tunnel  10  based on the signals from sensors  26 ,  28 ,  30 .  
         [0039]     Control unit  22  can be designed to associate location data with each sensor  26 ,  28 ,  30  so that the signals or data provided by each sensor  26 ,  28 ,  30  to the control unit  22  is/are associated with the location of the sensor. In this manner, the control unit  22  is able to determine where the fire is located based on which sensors  26 ,  28 ,  30  register the presence of the fire or conditions indicative of the fire. The location of the fire could be determined relative to one end of the tunnel  10 , i.e., a determination is made that the fire is located 850 feet from one end of the tunnel  10 , or designated zones of the tunnel  10  so that the location of the fire would be in one (or more) of the zones. As noted above, the zones can be defined between each adjacent pair of curtain assemblies  14 .  
         [0040]     Fire protection system  12  also includes a system for suppressing the fire once its location is determined. Specifically, fire protection system  12  includes fixed fire extinguisher unit  32  mounted on the tunnel wall  18 . Although only one side of the tunnel wall  18  is shown in  FIG. 2 , the opposite side of the tunnel wall  18  could be similar equipped with sensors  26 ,  28 ,  30  and/or fire extinguisher units  32 . Preferably, both sides of the tunnel wall  18  are equipped with fire extinguisher units  32 .  
         [0041]     Fire extinguisher units  32  can be any type of fire extinguisher device which is remotely activated to generate a fire suppression agent, such as an aerosol generator-type of fire extinguisher. An exemplifying fire extinguisher unit  32  is shown in  FIG. 4  and comprises three aerosol extinguishers  34  arranged side-by-side and separated from one another by a ceramic divider  36 . Each aerosol extinguisher  34  include a combustible aerosol-forming compound  38  and a block of oxidation and/or cooling material  40  arranged between the aerosol-forming compound  38  and discharge ports  42 . Possible aerosol-forming compounds for use in the invention include those described in U.S. Pat. Nos. 5,831,209, 6,042,664, 6,264,772 and 6,689,285 (all of which are assigned to R-Amtech International, Inc.). Alternative aerosol extinguishers for use in the present invention are disclosed in U.S. patent application Ser. Nos. 11/234,733 and 11/234,625, the entire disclosure of each of which is incorporated herein by reference.  
         [0042]     The fire extinguisher units  32  including three aerosol extinguishers  34  can be spaced a distance of, for example, 5 feet from one another. The capacity of the aerosol extinguishers  34  and spacing of the fire extinguisher units  32  from one another can depend on several factors, including, for example, the width and height of the tunnel  10 . Further, each aerosol extinguisher  34  can be designed to generate fire suppression agent at the rate of about 100 grams per cubic meter.  
         [0043]     Since the fire suppression agent produced by an aerosol-type fire extinguisher can be harmful to people, control unit  22  can be designed to allow for a delay between the determination of the existence of a fire in the tunnel  10  via sensors  26 ,  28 ,  30  and the activation of the fire extinguisher units  32 . This delay allows people not critically injured by the accident which gives rise to the fire to exit the area of the fire which is to be flooded with fire suppression agent from the aerosol extinguishers  34 .  
         [0044]     Once the location of the fire is determined by control unit  22 , it not only determines which fire extinguisher units  32  should be activated, it also directs the release of the curtains  20  from the curtain assemblies  14  immediately in front of and behind the fire, i.e., to contain the fire within a tunnel segment or zone. The fire suppression agent can be generated by the fire extinguishers  34  substantially simultaneously with the release of the curtains  20 . Alternatively, the curtains  20  could be released and a time delay provided before the activation of the aerosol extinguishers  34  to allow the curtains  20  to drop to a position close to or in contact with the bottom of the tunnel  10 .  
         [0045]     In addition to remotely activated fire extinguisher units  32  to aid in suppressing the fire, the fire protection system  12  also includes one or more systems to aid in enabling people in the tunnel  10  to exit from the tunnel  10 . One system is a series of speakers  44  mounted to the tunnel wall  18  and coupled to the control unit  22 . Control unit  22  can be designed to cause speakers  44  to provide a recorded message relating to evacuation of the tunnel  10  or a real-time message provided by an individual monitoring the control unit  22 . In the latter case, the fire monitoring personnel can visualize the fire via sensors  30 , view people in the tunnel  10  and provide specific directions for these people to the nearest emergency exit or tunnel entrance. In the case of recorded messages, the messages may be general messages designed to aid people to avoid the harmful effects of the fire, such as a message to stay low and move to the side of the tunnel or the messages might be directions to the nearest exit or actions to be undertaken to minimize the potential harm from the fire, smoke, heat or gases. Also, the speakers  44  could be used to warn people near the fire that the area around the fire is about to be flooded with fire suppression agent and therefore, they should leave that area immediately.  
         [0046]     Another system which aids people to exit the tunnel  10  is a series of infrared strobe lights  46  arranged on the tunnel wall  18  and designed, for example, to indicate the direction to an exit out of the tunnel  10 , e.g., an emergency exit. Strobe lights  46  illuminate a portion of tunnel  10  and will assist people in seeing the bottom of the tunnel  10  to enable them to flee the fire. Also, the strobe lights  46  can aid fire and rescue personnel when operating in the tunnel to suppress the fire and evacuate trapped people.  
         [0047]     Control unit  22  controls the fire protection system  12  and to this end includes hardware and software to allow for communications with sensors  26 ,  28 ,  30  and for issuance of activation signals to curtain assemblies  14 , fire extinguisher units  32 , speakers  44  and strobe lights  46 . The connections to and from control unit  22  may be by means of wired connections or wireless connections. Control unit  22  may be situated inside or outside of the tunnel  10 .  
         [0048]     Control unit  22  processes the input from the sensors  26 ,  28 ,  30  to analyze whether the sensors  26 ,  28 ,  30  indicate the presence of a fire in one of the tunnel zones. This analysis can be aided by associating each sensor  26 ,  28 ,  30  with an indication of the zone in which it is located. Thus, detection of a fire by one of the sensors  26 ,  28 ,  30  will enable the control unit  22  to consider the location of the fire to be in the zone in which that sensor is located. Once the zone in which a fire is detected is known, the control unit  22  directs activation signals to the curtain assemblies  14  at the ends of that zone, to the fire extinguisher units  32  in that zone, to speakers  44  and to strobe lights  46 . Activation of the fire extinguisher units  32  is therefore electronic and automatic based on the detection of a fire via one or more of the sensors  26 ,  28 ,  30 . The activation of the speakers  44  and strobe lights  46  does not have to be limited only to the zone in which a fire is detected but may be a plurality of zones or all zones since the messages provided from speakers  44  and light provided by strobe lights  46  may be needed by people in zones other then the one with the fire and the lights from strobe lights  46  are useful to fire and rescue personnel.  
         [0049]     Control unit  22  can also be programmed to alert a manned fire and rescue facility about the existence of a tunnel fire  10 . To this end, the control unit could include a communications device.  
         [0050]     Instead of automatic activation of the fire extinguisher units  32  via control unit  22 , a system for providing thermal and/or manual activation of the fire extinguisher units  32  can be provided. In a thermally activated system, a fire-detecting or fire-condition detecting sensor is arranged in connection with each fire extinguisher unit  32  or aerosol extinguisher  34 . When this sensors detects a fire or fire condition, e.g., heat in excess of a threshold, the aerosol extinguisher  34  is activated.  
         [0051]     While particular embodiments of the invention have been shown and described, it will be obvious to those skilled in the art that changes and modifications may be made without departing from the invention in its broader aspects, and, therefore, the aim in the appended claims is to cover all such changes and modifications as fall within the true spirit and scope of the invention.