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Recommendations for a National Mass Patient and Evacuee Movement, Regulating, and Tracking System

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Appendix F: Resource Requirements Models

Models that estimate resource requirements can complement resource availability systems (Appendix E) by estimating the "gaps" (i.e., the difference between what's required and what's available) and therefore the resource levels that neighboring jurisdictions or the Federal government could potentially be asked to fill.  These models can be used as part of a planning process to determine shortfalls and thus help drive investment decisions.  In addition, the models could be used during an incident to estimate resource shortfalls at that moment. 

This section briefly describes two AHRQ-funded resource requirements models related to mass casualty or evacuation incidents—the Surge Model and the Mass Evacuation Transportation Model.  The latter model was developed under the same contract as the recommendations for the National System; separate reports to the Agency for Healthcare Research and Quality (AHRQ) include the model description and user manual for the Transportation Model.

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AHRQ Hospital Surge Model

The AHRQ Hospital Surge Model, developed by Abt Associates, Weill Cornell Medical College, and Gryphon Scientific, estimates the hospital resources needed, by day, to treat casualties arising from various weapons of mass destruction attacks. The Hospital Surge Model includes ten different scenarios:

  • Biological (anthrax, smallpox, and pandemic flu).
  • Chemical (chlorine, sulfur mustard, or sarin).
  • Nuclear (1 KT or 10 KT explosion).
  • Radiological (dispersion device or point source).

When the Hospital Surge Model is run, the user selects one of the above scenarios and specifies the number of casualties that their hospital(s) will need to treat. Casualties are treated, as necessary, in the emergency department (ED), in the intensive care unit (ICU), or on a general medical/surgical bed ward. Hospitals are assumed to have unlimited capacity and provide a standard level of care to all casualties-that is, the Hospital Surge Model assumes that care is not degraded by the surge in patients or by resource constraints. Eventually, casualties in the model are either discharged or die in the hospital(s). While patients are in the hospital(s), the Hospital Surge Model estimates the amount of resources (e.g., personnel, equipment, supplies) they require.

For the selected scenario, the Hospital Surge Model estimates:

  • The number of casualties in the hospital(s) by hospital unit (ED, ICU, or floor) and day.
  • The cumulative number of dead or discharged casualties by day.
  • The required hospital resources (personnel, equipment, and supplies) to treat casualties by hospital unit and day.

Information about the Hospital Surge Model is available at

The Surge Model incorporates the AHRQ Bioterrorism and Epidemic Outbreak Response Model (BERM) Model, which estimates the number of staff needed to operate a mass prophylaxis center.85  Researchers from Weill Medical College of Cornell University developed the BERM.  Based on the number of people to be prophylaxed, the length of the campaign, characteristics of the prophylaxis clinic patient flow, speed of patient processing, and the bioterrorism release scenario, BERM calculates the number of staff required to prophylax the population in a given timeframe and the type of staff required to complete the campaign in the given timeframe.  The BERM model is available at

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Mass Evacuation Transportation Model

As noted at the beginning of this report, one of the two objectives of Abt Associates' contract with AHRQ was to build a Web-based Mass Evacuation Transportation Planning Model for use before a mass casualty/evacuation incident to estimate the transportation resources needed to evacuate patients and evacuees from health care facilities and other locations. 

The transportation model calculates the time necessary for evacuation of patients from designated evacuating locations to receiving facilities. It allows a user to designate patient types, prioritize patients, and consider evacuation of any number of facilities with the available vehicles. Furthermore, the model will show bottlenecks and overtaxed resources so that planners can prioritize resources. The model inputs include:

  1. Evacuation Resources: The fleet of vehicles available in an emergency is a key input of the model.  The user must identify how many ALS and BLS ambulances, wheelchair vans, and buses are available for use in an emergency, and how many patients each vehicle may carry. It is assumed that patients are ready for pickup by the emergency vehicles and only require a minimum loading time before transport.
  2. Facilities: Users can input any number of facilities into the model. Facilities can be divided into types such as nursing homes and hospitals, if patients from one type of facility should not be transported to another type of facility. With information on the location of the facility, its capacity, its surge capacity percentage (percent over 100% capacity that a hospital could accept patients in an emergency), and its patient mix, the model will calculate the best distribution of patients to facilities in order to minimize travel time.
  3. Patient mix: Each facility (or facility type) may have a different patient mix. Specifically, the model needs to know what proportion of patients will need to be evacuated with ALS, BLS, wheelchair vans, or buses. Patients are thus grouped by acuity rather than the specific diagnosis, and can be prioritized to ensure that the most severely ill patients travel the least amount of distance.
  4. Additional inputs: Several additional features include: accounting for traffic by adding time to the expected travel times, changing the loading or unloading time for each vehicle, designating overflow capacity outside the city for patients which cannot be accommodated. 

The primary output of the model is the number of hours necessary to transport patients from evacuating facilities to receiving facilities. In addition to the total hours for evacuation, the model shows the number of hours and the number of trips made by vehicle type, showing which are most in demand. This will help planners anticipate resource needs.

The Mass Evacuation Transportation Model is available at


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AHRQ Publication No. AHRQ-09-0039-EF
Current as of February 2009


The information on this page is archived and provided for reference purposes only.


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