National Academies Press: OpenBook

Emergency Response Procedures for Natural Gas Transit Vehicles (2005)

Chapter: Chapter Three - General Considerations for Emergency Response

« Previous: Chapter Two - Considerations Related to Use of Natural Gas
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Suggested Citation:"Chapter Three - General Considerations for Emergency Response." 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 7
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Suggested Citation:"Chapter Three - General Considerations for Emergency Response." 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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Suggested Citation:"Chapter Three - General Considerations for Emergency Response." 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.
×
Page 9
Page 10
Suggested Citation:"Chapter Three - General Considerations for Emergency Response." 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 10

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7TYPES OF EMERGENCY RESPONDERS Although it is common and often accurate to think of munici- pal fire and police departments as the only emergency respon- ders, the first responders to a natural gas incident may extend beyond emergency response professionals, such as police officers and firefighters, to include • Transit operating employees, such as drivers and supervisors; • Transit maintenance employees, such as vehicle fuelers and mechanics; • Transit police and security guards; and • Members of the public. As emergency responders, fire and police personnel have a great deal of training and experience in handling emergency situations, and they have access to emergency equipment and resources. However, they may have limited experience with transit buses and facilities, because there are relatively few critical incidents involving transit. In many cases, transit employees are the first responders. Because transit employees are knowledgeable about transit vehicles and facilities, they may be the most likely to recog- nize abnormal conditions and be the most familiar with facil- ities, vehicles, controls, and valves. The initial response may also be provided by someone among the public who happens to be in the vicinity. Although the competence of the general public is often denigrated, analy- sis of actual incidents shows that such individuals have often provided valuable initial responses. Although some individu- als may be uninformed and untrained, the general public may also include off-duty or former transit employees, police offi- cers and firefighters, and medical and military personnel, as well as people with a variety of industrial training and experi- ence. The issue here is how to guide the response of the general public in those circumstances where immediate action is nec- essary, while to the degree possible protecting them from harm. USE OF INCIDENT COMMAND SYSTEM FOR MANAGEMENT OF PROFESSIONAL EMERGENCY RESPONSE Incident Command System The Incident Command System (ICS) is a management tool for the command, control, and coordination of resources at the scene of an emergency. The use of the ICS has recently become common in firefighting, but the principles are con- sistent with classic management practices. The ICS recognizes that if an emergency response is to be effective, there must be an immediate response from those on the scene. Harm and damage can result if nothing is done dur- ing the wait for experts or resources, no matter how great their value. Nevertheless, as experts and resources become avail- able, they must be used. The ICS also recognizes that any response must be organized and that expertise and resources may derive from different organizations and agencies. The functions of the incident commander include planning, operations, logistics, and finance. At the start, the senior responder on the scene becomes the incident commander. As higher ranking people arrive, who presumably have more expertise and additional resources, there is an orderly hand- off of control and a logical division of labor. The ICS recognizes that for large, complex, or multi- jurisdictional incidents, a formal command structure must be developed for each function. This command structure rec- ognizes that the span of control must be limited, common terminology must be developed, communications must be integrated, and the use of resources must be coordinated. Additional information on the ICS is found in Appendix A. Incident Command System and Natural Gas Transit Incidents The initial responders to an incident involving natural gas vehicles or facilities are often transit personnel, and the tran- sit central dispatcher may be the first party to be notified of an incident. In the case of a bus incident, the first person on the scene is probably the driver. In the case of a facility inci- dent, the first person is probably a vehicle fueler or mechanic. Whoever it is, that person is the incident commander until relieved by a supervisor or emergency response forces. For natural gas incidents this means that • People who work with natural gas every day should be familiar with the first stages of the ICS. • People who are emergency responders should be aware of proper hand-off procedures and of the need to obtain status and other information from the initial responder. CHAPTER THREE GENERAL CONSIDERATIONS FOR EMERGENCY RESPONSE

8A basic requirement is to recognize the use of natural gas as a vehicle fuel. In this regard, there have been instances of responders and others confusing CNG or LNG with liquefied petroleum gas (LPG). LPG (commercial propane) is a com- mon gaseous fuel frequently used commercially for portable heating and by consumers for barbeque grills and other appli- cations. Anecdotal information shows that education con- tinues to be needed on the differences between CNG, LNG, and LPG. The fuel tanks for CNG buses have pressure relief devices (PRDs) as a safety feature to vent excess pressure. If exces- sive heat or mechanical failure causes the operation of a PRD, there may be a torch-like flame. In such a case, the role of the natural gas fuel in feeding a fire is clear. However, in other cases, it may not be clear whether the intensity of other fires is being increased by burning natural gas. Experience sug- gests that in most cases of natural gas bus fires, the use of nat- ural gas as a fuel does increase the severity of the fire. More- over, mere visual observation of a CNG bus is not sufficient to determine if the natural gas fuel tanks are full (and have the potential to vent) or have already vented and are empty. CNG vehicles are identified by the aforementioned blue CNG diamond on the rear of the bus (see Figure 1). Although the use of the blue CNG diamond on CNG buses has become universal, there is no uniform requirement for marking the exteriors of facilities where CNG or LNG is in use. In some jurisdictions, the appropriate National Fire Protection Association (NFPA) hazard diamond is used on the outside of buildings containing hazardous materials, as described in NFPA Standard 704, System for Identification of Futhermore, the initial responder should be aware of the need to brief the subsequent responders. • The ICS structure has a place for resource management. Transit personnel with knowledge of CNG or LNG should be considered as resources for incidents involv- ing those fuels. Emergency responders should know who those people are, what their expertise is, and how to contact them. OBJECTIVES OF EMERGENCY RESPONSE The five basic objectives of emergency response are these: 1. Assess the situation. 2. Assist those involved and treat the injured. 3. Prevent further injuries and property damage. 4. Secure the scene and preserve evidence that could be lost. This evidence could be needed for an engineering investigation to establish a cause or for a criminal inves- tigation to fix blame. 5. Document what happened. Although the objectives are listed separately and sequen- tially, it is often the case that actions to achieve these objec- tives are taken simultaneously. All aspects of these basic objectives apply to the response to transit emergencies involving natural gas vehicles or facili- ties. However, for the purpose of this synthesis document, only the natural gas-related aspects of these response objectives will be considered. Those parts of the emergency response that are common to all types of emergencies, such as first aid, traffic control, or property damage procedures, will not be discussed here. Assess the Situation The first challenge of an emergency responder is to assess what has happened, what is happening, and what needs to be done in the midst of crowds, traffic, confusion, injuries, smoke, fire, or damage. Natural gas has characteristics that are different from those of diesel fuel and a different set of hazards. Implications for emergency response include the need to • Determine whether or not natural gas is being used through observing the blue CNG diamond identifica- tion on the rear of the vehicle or the presence of roof- mounted fuel tanks; and • Recognize the presence of and potential for natural gas leaks and releases, through odor, sound, or, in the case of LNG, visible vapor. FIGURE 1 Rear of natural gas bus; blue CNG diamond is shown at the lower right.

9ther damage. If an explosion has occurred, it may be that all one can do is to survey the damage; if a fatality has occurred, no treatment can reverse the result. The actions necessary to prevent additional damage depend on the situation. From the perspective of an emergency responder to nat- ural gas leaks and releases, several actions can be taken to prevent further damage or harm: • Verify the origin of the gas release and stop the release. • Remove people and property from the vicinity of the release or move the equipment with the release away from people and property. People should be moved upwind from any actual or suspected gas leaks or gas releases. • Prevent ignition. If natural gas is or has been released, the scene should be surveyed for ignition sources. Ignition sources should be removed or prevented. For example, if a bus with a gas leak or gas release is under a bridge or overpass, vehicles should be prevented from passing overhead. The ignition possibilities of emergency equip- ment must also be recognized, including abrasive cutting saws and engine-driven rescue tools. • Be wary of static electricity. For a flammable gas, such as natural gas, static electricity is always a potential igni- tion source. This is especially true if the relative humid- ity of the air is low. In rapidly flowing gases, the motion of entrained particles can cause the buildup of static charges. • Ventilate enclosed areas, considering that natural gas is lighter than air. LNG fuel vapors may be heavier than air until they warm. Note that once the gas is gone, there are no more hazards. A meter to measure combustible gas can be used to deter- mine that all gas has dissipated. Some locations use non- odorized natural gas. In such cases, combustible gas meters are the only way to detect the presence of natural gas, so they should be widely available and routinely used. For incidents involving natural gas releases, assistance required from emergency responders will normally include recognizing areas where there could be imminent harm and moving people from these areas to a safe place. Because some of the properties of natural gas may be unfamiliar, expert guidance may be necessary in identifying areas that are or are not danger zones. However, there is anecdotal evi- dence that the extent of the flammable zone associated with a natural gas release is sometimes greatly overestimated and additional study is needed to develop appropriate evacuation guidelines. As for the implications pertaining to natural gas-related fires, CNG fuel tanks are pressure vessels that require pro- tection from excessive pressure and are equipped with PRDs. LNG fuel tanks also have pressure relief valves, which are designed to reclose after the pressure falls. the Hazards of Materials for Emergency Response. Figure 2 shows an NFPA diamond for natural gas. Assist Those Involved and Treat the Injured Large numbers of people may be involved in a transit-related emergency situation. The immediate response to an emer- gency requires that assistance be provided to the people involved and that those who are injured be identified and treated. Although providing assistance for people and medical treatment of injuries is important, the procedures and treat- ment are not specific to incidents involving natural gas. Thus, such procedural information is not included in the scope of this document, which is focused on natural gas-related issues. With respect to human exposure to natural gas, it should be noted that natural gas is widely used for home cooking and the toxicity of natural gas is very low, unless there is enough gas to displace the oxygen in the air. Therefore, no particu- lar toxic effects are expected from occasional exposures to natural gas. Prevent Further Injuries and Property Damage In some cases, an emergency response can be effective in lim- iting further damage and harm. For example, extinguishing a fire before it spreads can prevent injuries to people and limit property damage. Moreover, prompt treatment can greatly assist an injured person toward a successful recovery. Fur- ther injuries are prevented by either moving people from harm’s way or ending the conditions that cause injury. However, in other cases, there is little that can be done to prevent further harm. For example, after a vehicle or struc- ture is totally engulfed in flames, it cannot be saved from fur- 1 0 4 FIGURE 2 NFPA fire diamond for natural gas.

A PRD is designed to fully vent the contents of a com- pressed gas cylinder that has been exposed to excessive tem- peratures. Once activated, the PRD will not reclose, and safety codes (for good reason) prohibit any valve in a PRD vent line. If there is a fire nearby to provide an ignition source, it is likely that the natural gas will ignite as well. There- fore, if possible, fire control efforts should be directed toward keeping a fire from approaching fuel containers. If a fire from a PRD release does occur, it is not possible to cut off the gas supply. Thus, the response to a fire fed by a PRD release may need to be limited to protecting nearby property from exposure to heat from the fire. In general, large natural gas flames fed by high-pressure supplies are difficult to extinguish. In addition, it may be dangerous to do so, because of the risk of gas accumulation and subsequent explosion unless the supply of natural gas can be cut off. Secure the Scene and Preserve Evidence Although determining the cause of an incident is mostly the responsibility of others, emergency responders do have a responsibility to collect information on the incident, particu- larly information that cannot be observed by investigators at a later time. For example, in the case of a traffic accident, police personnel must note the locations of other vehicles, pavement conditions, and other factors. In the case of natural gas incidents, there are aspects of the situation that should be recorded to facilitate a subse- 10 quent investigation. Some of these are related to the ability of natural gas to dissipate. Thus, for subsequent investiga- tion, it is generally desirable to know about and to document the following: • Was there an odor of natural gas? • Was there a sound of escaping gas? • What was the status of combustible gas alarm systems? • Were readings taken with a combustible gas meter? What were the readings and where were they taken? • Was there venting of gas? If so, when and where did the venting occur? • Was there a fire? If so, where was the fire most intense? In many cases, someone who is knowledgeable about nat- ural gas fuel systems and who can recognize important evi- dence should be called to the scene. Document What Happened For both investigative and legal purposes, it is essential to document the incident and the emergency responders who are called to record what they observe. The requirements for natural gas incidents are basically the same as for any other incident. However, given that nat- ural gas incidents are relatively rare, it is important to have a debriefing to review what happened, evaluate the response procedures, and determine if improvements in the emergency response procedures are required.

Next: Chapter Four - Transit Experience with Natural Gas »
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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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