3 EXPLANATION OF NO-NOTICE INCIDENTS
A little- or no-notice incident is one that occurs unexpectedly or with minimal warning. The lack of warning and the quick response time required introduce distinct challenges for evacuating at-risk populations. No-notice incidents do not provide emergency responders sufficient time to prepare for a specific incident. This greatly affects agencies' abilities to pre-activate emergency protocols, pre-position needed assets, and warn and direct the public. No-notice evacuations require a significantly different approach to planning than advance-notice evacuations because they will be based on a set of capabilities and strategies that will likely be more limited in the time and resources available for implementation. This section provides a general overview of the likely scales and consequences of no-notice incidents and also provides examples of such incidents. The unique issues and problems associated with no-notice incidents are discussed in Section 4, Considerations in a No-Notice Context.
No-notice incidents may be natural or manmade, can be localized or widespread, and have a variety of primary and secondary consequences. Some examples of no-notice incidents include earthquakes, tsunamis, chemical spills and explosions, blackouts, and terrorist attacks. It is also possible that incidents with typically predictable patterns can become no-notice incidents when their behavior differs from what is expected. An example is a wildfire that breaks a fire line and moves toward a populated area.
Due to the nature of no-notice incidents, rapid assessment and response to the incident is critical to successful evacuation operations. As Figure 3.1 shows, no-notice evacuation decisions follow the onset of the precipitating incident and require quick activation of support activities, regardless of the type or scale of incident.
The majority of incidents that precipitate a no-notice evacuation occur within a very local area. These are typically manmade, whether accidental or intentional, and occur most often in urbanized locations. Examples of such incidents include structure fires, gas leaks, chemical spills, transportation accidents, and terrorist attacks involving conventional explosives. Some natural incidents, such as sinkholes, tornadoes, and flashfloods, also affect only a small area.
Evacuations from a localized area are, by nature, smaller in scope. This may be limited to the population of a single building (in which case centralized coordination of an evacuation is likely unnecessary) or range up to the evacuation of an area of 10-15 city blocks. Usually, at-risk populations are smaller, and evacuees typically need to be moved only a short distance to be safeguarded against the precipitating hazard. Evacuation routes, assembly areas for evacuees, and sheltering facilities are also smaller and less resource-intensive than in a wide-scale evacuation. Localized evacuations typically have certain characteristics that should be considered during preplanning and preparation.
The types of localized incidents that precipitate an evacuation will almost always involve on-scene activity by emergency response personnel, separate from any efforts underway to execute an evacuation. Whether extinguishing a fire or containing a hazardous leak or spill, personnel from fire, law enforcement, and other response agencies will respond to the precipitating incident. Because of the nature of a localized incident, first responders will often have to gain entry into the site from which citizens are being evacuated. The need of first responders to gain access to the site with vehicles and equipment, and to move freely as they operate on-site to eliminate the hazard, may complicate or interfere with the management of the evacuation.
Larger incidents may affect an entire city or region. These can be either natural or manmade and have a variety of primary, and often secondary, consequences. Examples of wide-scale, no-notice incidents that would likely require a sizeable evacuation include earthquakes, tsunamis, chemical releases that result in a large moving toxic cloud (plume), explosions at specialized sites such as liquid natural gas facilities, and terrorist attacks using unconventional explosives (e.g., radiological dispersal devices).
Evacuations that result from such incidents will likely involve a tremendous number of evacuees, possibly from more than one jurisdiction, who need to move from the at-risk area(s). This will require intensive efforts on the part of emergency managers, first responders, volunteer staff, and transportation personnel to coordinate, transport, and shelter the affected populations, and therefore will place great demands on staff and resources. Some local agencies may not be adequately prepared with sufficient resources to address a wide-scale no-notice situation. Moreover, the emergency response staff may be among those directly affected by the incident and may be unavailable to assume their duties.
With wide-scale incidents, first responders will likely be spread out through the entire affected area, even if large portions of available first responders are focused on specific problems (such as collapsed buildings) or large numbers of injured people who need immediate medical attention. As such, even though first responders are likely to be working at one or more critical locations and their localized activity should not directly hinder the corresponding wide-scale evacuation, they may not be available to help support the actual evacuation effort. This element will vary greatly, depending on the nature and severity of the precipitating incident. Furthermore, first responders' primary role is life saving/sustaining activities; as a result, transportation operations staff - including full-function service patrols - may be handling first-response-type activities at highway incident scenes until additional support resources arrive.
Large incidents that precipitate a wide-scale evacuation typically cause widespread damage (through both primary and secondary effects) and are therefore more likely to compromise critical infrastructure in a manner that hampers evacuation movement. Particular elements of the transportation system, such as bridges and tunnels or even the highway or subway systems, are more vulnerable to damage from seismic and explosive incidents, rendering them unsafe for use. If these sites are located on evacuation routes, those routes may be unavailable, and alternatives will need to be identified using preplanning data and incident-specific information. In cases where the transportation network is severely restricted by such damage, sheltering in place may be a better short-term alternative for at-risk populations until evacuation routes can be restored for use. During the response, highway engineers and highway operations personnel will likely perform a wide range of activities, such as structural integrity assessments, situation assessments, debris clearance, traffic incident management, etc.
|POTENTIAL NO-NOTICE EVACUATION TRIGGERS|
Hazardous Materials Spill
|Localized Incidents||Wide-Scale Incidents|
|Affect small area||Affect city or region, widespread damage|
|Localized evacuation||Large-scale evacuation|
|Smaller, less resource-intensive evacuation effort||Resource intensive, likely will involve multi-jurisdictional response|
|Structure fires, gas leaks, vehicular accidents, flashfloods||Earthquakes, radiological dispersal devices, chemical releases involving a plume|
PRECIPITATING INCIDENTS AND ASSOCIATED ISSUES
The types of incidents that result in no-notice evacuations often have certain characteristics that may complicate the execution of an evacuation. Some of the following elements have been introduced above, but it is important to highlight these individually.
- Details as simple as the location and nature of an incident and the time of day in which it occurs could affect the size of the affected population greatly. In downtown areas of large cities with high-rise buildings, even an evacuation of only one or two blocks may involve the movement of thousands of people. In contrast, incidents in less densely populated areas or at remote locations will likely affect fewer people, therefore requiring a smaller response. Evacuation planners will need to anticipate the types of areas and populations affected by their plan.
- On-scene emergency responders may be present at a site from which at-risk people are being evacuated. These responders' primary function may be to address the life saving and sustaining missions caused by the precipitating incident, as opposed to directly supporting the evacuation. They will often need access to the site for their equipment and vehicles. An inbound right-of-way needs to be established, running in opposition to the evacuees' direction of movement. Furthermore, the responders' presence and activities at the site may unintentionally obstruct or hinder the movement of evacuees away from the danger.
- The precipitating incident may create potential hazards to responders, which prevent or delay them from assisting evacuees. Threats such as toxic contamination, radiological exposure, and structural instability will require responders to implement specialized protective measures that slow and reduce the effectiveness of their activities. This will result in an evacuation effort that is more complicated and takes more time to execute, putting evacuees at greater risk.
- Contamination in the affected area may impose severe restrictions on the movements of evacuees and responders. People who have potentially been contaminated will need to be isolated from unaffected populations to avoid the spread of harmful agents. On-site mass decontamination units will likely be needed to screen victims (and exiting responders) before they can be transported and sheltered with the general population. Such activity will slow the movement of such victims from the at-risk area to shelter or care facilities.
- Large-scale incidents have potentially significant effects on the systems and infrastructure needed to coordinate and execute an evacuation. These may affect transportation networks and responder resources, as well as command and communication facilities. Damaged bridges and tunnels may be rendered unusable, eliminating key evacuation routes. Shelters and other destinations for evacuees may be damaged or destroyed. ITS equipment such as traffic cameras and DMSs may be non-operable after sustaining damage during the incident. EOCs and TMCs are also susceptible to damage or to being rendered inoperable by the loss of power or communications systems. Communication networks may cease to function if key relay points are damaged.
No-notice incidents can occur at any time under any circumstances, and can affect one block of or the entirety of a jurisdiction. Evacuation personnel will not have sufficient time to directly prepare for a specific incident due to limited warning; they must clearly understand the challenges posed by a no-notice incident and its resulting evacuation to best produce an effective response.