National Academies Press: OpenBook

Emergency Response Procedures for Natural Gas Transit Vehicles (2005)

Chapter: Chapter Five - Case Studies

« Previous: Chapter Four - Transit Experience with Natural Gas
Page 13
Suggested Citation:"Chapter Five - Case Studies." National Academies of Sciences, Engineering, and Medicine. 2005. Emergency Response Procedures for Natural Gas Transit Vehicles. Washington, DC: The National Academies Press. doi: 10.17226/23328.
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Page 13
Page 14
Suggested Citation:"Chapter Five - Case Studies." National Academies of Sciences, Engineering, and Medicine. 2005. Emergency Response Procedures for Natural Gas Transit Vehicles. Washington, DC: The National Academies Press. doi: 10.17226/23328.
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Page 14
Page 15
Suggested Citation:"Chapter Five - Case Studies." National Academies of Sciences, Engineering, and Medicine. 2005. Emergency Response Procedures for Natural Gas Transit Vehicles. Washington, DC: The National Academies Press. doi: 10.17226/23328.
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Page 15

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13 The following three case studies serve to illustrate the cur- rent emergency response situation at transit agencies. CASE STUDY I This transit agency serves a major city and has hundreds of CNG buses in its fleet. As with many other transit agencies, when CNG buses were first introduced there was extensive training of all staff at the facility where the CNG buses were located. Furthermore, like many transit agencies with CNG buses, this one invited the fire department to its site and those personnel were briefed. The briefings included information about the following: • Properties of CNG and its relative safety; • A description of the CNG buses, including the locations of fuel tanks, PRDs, and fuel system shutoff valves; and • Instructions for access to various vehicle compartments. When several fires occurred that involved CNG buses (the fires did not originate in the CNG fuel system), the response from the emergency responders was not what the transit agency anticipated. The fire department let the buses burn and did not mount an aggressive attack on the fires, while the police response was to cordon off a large area. This transit agency believes that communications between the fire officials who came to visit the transit facility for an inspection and briefing and the crew of firefighters who actually responded were not effective. Those firefighters were from the principal jurisdiction (the jurisdiction that was briefed by the transit agency) in the metropolitan area. However, the agency also noted, on reflection, that no writ- ten materials had been given to responders describing the desired procedures. The agency believes that written materi- als might have improved the communications process. More- over, it realized that a half-dozen other fire jurisdictions are served by CNG buses, but that their fire departments were not involved in the on-site briefings. CASE STUDY II This transit agency has approximately 150 CNG buses. As with other transit agencies, this agency met with local fire officials on multiple occasions to educate them on the safety properties of CNG and the type of CNG equipment in use by the agency and to provide information about transit vehicles and equipment. The agency also prepared a binder that it sent to 31 gov- ernment agencies that provide emergency response in its ser- vice area. This binder was intended to be a “guide for first responders.” It contained these items: • A list of emergency telephone numbers. • A list of hazards associated with CNG buses. • A list of switches, valves, and actuators. • A photograph of the access key needed to open bus compartment doors. • A series of color photographs of each type of bus, which had callouts that show the locations of the master switch, the battery disconnect switch, the fuel shutoff valve, the PRD vent outlets, and other safety features. Subsequently, two CNG bus fires occurred. When the fire- fighters who responded saw that CNG was on board, they did not extinguish the fire, but only protected adjacent property from exposure to the fire. In one case, the bus was only a few months old, so the economic loss was relatively severe. The causes of the two fires were unrelated to the use of CNG. The CNG buses had functioning fire suppression systems. Although these systems did suppress the fire for a time, they did not extinguish it, and damage continued to occur. Agency staff believes that this is probably a result of the large amount of heat in the engine compartment. CASE STUDY III—FIREFIGHTER PERSPECTIVE ON RESPONDING TO A BUS FIRE The following description of the firefighter’s perspective on responding to a bus fire is based mainly on discussions with staff at a training academy for firefighters. The acad- emy staff emphasized that firefighter response is highly variable and depends on the experience, philosophy, and personal preference of the fire commander, as well as on the particular circumstances. Lessons learned for transit agen- cies are featured here. CHAPTER FIVE CASE STUDIES

14 As firefighters arrive and size up a situation, they recog- nize that this is a vehicle fire, that no buildings are involved, and determine whether the occupants of the vehicle have been evacuated. Most commonly, vehicle fires involve auto- mobiles. The firefighters have been trained to fight automo- bile fires and are aware that: • Gasoline fuel tanks can explode. • Air bags can explode. • Various piston-operated hardware, such as the struts that hold a hood or a hatch cover open, can become lethal missiles when hot. • Modern automobiles contain a lot of plastics and poly- mers, and the combustion products from these materi- als can be extremely toxic. Thus, it is now common for firefighters to wear breathing apparatus even outdoors when in the vicinity of a burning vehicle. • Opening the hood on a burning car is difficult. Getting inside the vehicle to operate the hood release is danger- ous; so is manually unhooking the front hood latch. Even if one uses heavy tools, prying a hood open by brute force is often frustratingly difficult. When an incident requiring fire department response is reported, an alarm is communicated to the dispatcher. The dispatcher not only assigns crews and equipment but also informs the responders about the nature of the incident and about any special hazards the crew may encounter. In regard to buildings, particularly commercial or industrial properties, this information is generally organized by street address and may be quite detailed, based on previous fire inspections. In the case of a bus fire, the information communicated to the responding crew may be brief and sketchy. The crew will know that there is a bus at a certain intersection. However, those respondents may not know the type of fuel used by the bus and they may not even know whether the bus is a transit bus or a school bus until they arrive on the scene. Lessons learned are: • The transit dispatcher should inform the fire department dispatcher about the type of equipment involved. • The fire department dispatcher should have information on transit equipment and transit bus-related procedures, because if the database of briefing information is street- address oriented, it is easy for mobile equipment, such as transit buses, to “fall through the cracks.” • Because the call for help may be vague or because the public is not considered a reliable source of information concerning the type of equipment involved, the fire- fighters may arrive on the scene without any briefing. When the responders arrive, they need to size up the situ- ation. (See Figure 3 for an example of what responders might see. Note the vertical flame from venting PRD.) Evaluating the situation means answering questions such as: • What is the nature of the emergency? • Is there a gas release? • Is there a fire? • What is on fire? • Are there any casualties or people in need of rescue? • What is the size of the fire? • Where is the nearest supply of water and is it functional? • Is there a need for traffic control? • Is there anything unusual about the situation; for exam- ple, the use of CNG as fuel? Lessons learned are: • Firefighters have many items to address when they first arrive at a fire. • Seeking detailed information on vehicle construction, from a reference binder, may have to wait until other, more immediate, goals are addressed. • Firefighters may not immediately notice that the vehi- cle is a CNG bus. However, many firefighters are famil- iar with the distinctive roof-mounted fuel tank enclo- sure used on many CNG buses. FIGURE 3 What firefighters might observe upon arriving on the scene of a natural gas bus fire. (Used with permission from Peter Jensen 2003.)

15 • If it is possible to get the hood open, the fire will get a fresh supply of air and is very likely to flare up in the faces of the firefighters. Also, fluid-filled containers may explode in their faces. Given the latter potential hazard, a penetrating nozzle is sometimes used on vehicle fires. This is a water nozzle that is hammered through the sheet metal that covers the engine or passenger compartment. For example, a penetrating noz- zle might be used on a school bus fire to get water inside the passenger compartment without opening up the vehicle. In any case, an automobile becomes a total loss so quickly that little reduction in property damage is gained by trying to extin- guish the fire aggressively. In addition, some fire crews may have experience with truck fires. They are aware that trucks often carry hazardous materials. This is true not only for placarded cargo trucks, but also for smaller vehicles. For example, a plumber’s van may carry acidic drain cleaner or a cylinder with welding gas. Thus, truck fires are also problematical for an aggressive, close attack. All these considerations make firefighters reluctant to mount an aggressive attack on a burning vehicle. The risk– benefit ratio is not very favorable: an aggressive attack on the fire involves risk of injury to the firefighters and does not offer much potential for a reduction in property damage. The responding crew may find that the vehicle on fire is a transit bus, and that it is a CNG bus. That crew must then decide on a plan of attack. Given the number of transit bus fires compared with the number of fire stations and fire crews in the city, it is likely that this crew has never seen a transit bus fire before. A CNG bus fire can be a once-in-a-career fire for most fire crews. However, as noted, the crew may have experience with automobile and truck fires, as well as with fires involving propane and with natural gas leaks and fires in buildings. The responding crew’s perspective may include the following: • From their experience with gas leaks in buildings, the responders are aware that natural gas that ignites in a confined space can explode. • From their experience with propane, they know that propane fuel tanks can explode. Also, if they are acquainted with CNG tanks, they know that PRDs can release without warning, and that if the gas jet ignites, a large jet flame with a significant radiant exposure will result. They may know that PRDs are present, but do not know the number, location, and direction in which the devices are pointed. • They do not know that CNG transit buses are expensive and may cost from one-third to one-half million dollars. However, if they did know, that amount of money would be considered insignificant compared with any risk of firefighter injury. • They do not realize that even badly damaged transit buses are routinely rebuilt and put back on the road. Implications for transit are: • It is unlikely that the responding crew will have previ- ously fought a transit bus fire. Furthermore, the crew may not have received needed information from the dis- patcher while responding. • Without specific training, the responding crew will likely base its response on the situation that most closely approximates what it has been trained for and has expe- rience with—namely, automobile and/or truck fires. Accordingly, the responding crew decides on a strategy. It protects adjacent property from exposure to the fire. It cools the bus with streams of water from a distance. It does not approach the vehicle closely. (However, if it did approach the bus closely, the crew would consider an approach from the front to be the safest.) The crew does not open hatches or compartments until the fire is extinguished. Then the crew opens up the vehi- cle to look for hot spots that require further attention. The vehi- cle suffers extensive damage, but there are no injuries to the general public, no firefighter injuries, and no damage to adja- cent property. The operation is therefore considered a success.

Next: Chapter Six - Examples of Emergency Response Procedures »
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TRB’s Transit Cooperative Research Program (TCRP) Synthesis 58: Emergency Response Procedures for Natural Gas Transit Vehicles identifies and documents the state of the practice on emergency response protocols to incidents involving natural gas-filled transit buses. The report is designed to assist first responders to natural gas incidents—emergency response professionals such as police officers and fire-fighters; transit agency operations and maintenance employees, police, and security guards; and certain members of the general public.

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