Appendix F: Hurricane Evacuation Models and Tools
Over the past four decades of transportation infrastructure expansion and with the 9/11 disaster response and recent hurricane impacts, researchers and emergency management personnel have sought to better understand and predict the characteristics of evacuations. This research has led to the development of several models, which have contributed to planning for evacuations and, to a lesser extent, to the operational execution of evacuations. The following summarizes the current and most prominently applied models and tools used in two different contexts:
Operational Tools for Hurricane Modeling and Information Sharing
- SLOSH (Sea, Lake, and Overland Surges from Hurricanes)
- HURREVAC (HURRicane EVACuation)
- HAZUS-MH (HAZards US Multi-Hazards)
- CATS/JACE (Consequence Assessment Tool Set/Joint Assessment of Catastrophic Events)
- ETIS (Evacuation Traffic Information Systems)
Analytical Tools for Transportation Modeling and Analysis
- NETVAC (NETwork emergency eVACuation)
- MASSVAC (MASS eVACuation)
- OREMS (Oak Ridge Evacuation Modeling System)
While designed, developed, and deployed with different functionality, data requirements, user interface, and level of expertise and training required for operations, these modeling tools can be applied to assess some common objectives.
Operational Tools for Hurricane Modeling and Information Sharing
The most widely applied flooding model for evacuation analysis is the SLOSH model. Developed by the NWS to predict hurricane storm surge for a given set of conditions (e.g., hurricane strength, wind speed, and direction of movement, geography), it is also used to help plan evacuation routes and locate emergency shelters based on estimates of which geographic areas could be flooded under certain storm scenarios. The NHC, in coordination with Federal, State, and local organizations, has developed SLOSH models for over 38 water basins along the Atlantic and Pacific Ocean coastal areas; with 14 "SLOSH Basins" covering the state of Florida.
HURREVAC is a model developed specifically for hurricane evacuations. The model was developed on behalf of FEMA by the USACE for use by emergency managers. The model is applied as an open ocean path tracking and projection tool while a hurricane is approaching and projects the anticipated course once it makes landfall. It is an operational tool, assisting decision makers in advance of and during an evacuation. HURREVAC draws information from a wide variety of sources including the NHC, inundation estimates from the SLOSH model, and information on the location, remaining capacity, and flooding potential of all the shelters in the area. It also estimates the time required to evacuate an area, which emergency managers use in determining when to commence evacuations.
HAZUS-MH, developed by FEMA, is a loss estimation and risk assessment program covering earthquakes, hurricanes, and flooding. By modeling the physical world of buildings and structures and then subjecting it to the complex consequences of a hazard event, users can implement this tool to prepare for a natural disaster, respond to the threat, and analyze the potential loss of life, injuries, and property damage. In the HAZUS-MH program, three levels of intensity or detail can be applied, with each level utilizing base data requiring a progression of quality and detail input from the user. A user choosing the level of implementation would likely base the decision on the funds available for data gathering and input, as well as the level of detail required in the output. At a minimum, the model can allow a common assessment using base data taken from national publicly available data resources, and supplemented with more accurate and granular data from local users.
HAZUS-MH was utilized by Broward County, Florida Sheriff's Office personnel during Hurricane Jeanne, which struck South Florida on September 26, 2004. Utilizing wind swaths generated from FEMA's HURREVAC 2000 software program, the Sheriff's office integrated the wind data into the HAZUS application and updated the essential facilities information as it relates to public safety facilities to better gauge damage to them as well as to determine how many people would be utilizing designated shelters.
Developed under the guidance of FEMA and the Defense Threat Reduction Agency (DTRA), the CATS/JACE software provides disaster analysis in real time with an array of information integrated from a variety of sources. The software is deployable for actual emergencies with capabilities including contingency and logistical planning as well as consequence management.
The CATS program integrates hazard prediction, consequence assessment and emergency management tools with critical population and infrastructure data. It uses tools and data that predict the hazard areas caused by manmade events and natural disasters including earthquakes, and hurricanes. CATS assists with estimating collateral damage to facilities, resources, and infrastructure, and creates mitigation strategies for responders.
The U.S. DOT developed ETIS, another hurricane evacuation tool, in collaboration with FEMA. Created in direct response to significant traffic congestion problems occurring in southeastern states during Hurricane Floyd's 1999 near landfall, ETIS operates on a model that combines behavioral studies, data from past occurrences, and real-time data from ongoing incidents, including weather information, evacuation percentages, and tourist occupancy rates in affected areas.
ETIS is a GIS, Web-based tool that assists with collection and dissemination of transportation information during an evacuation. Transportation officials in each threatened state are responsible for inputting information for coastal counties on evacuation status, tourist occupancy, evacuation participation rates, and traffic count information. ETIS provides a platform for States and the FEMA Regional Operations Center to monitor the evacuation process. The system also provides a forecast of total cross-state traffic and the likely destinations of the evacuees.
Reports generated by ETIS that can be viewed through the Web site (www.fhwaetis.com) include:
- Shelter capacity by State
- Traffic count by State
- Traffic volumes by corridor
- Destination percentages by city
- Estimated State-to-State traffic.
In addition, a series of tables and roadway-network graphics provide emergency managers with crucial information to help with decisions regarding highway lane usage and the provision of emergency services.
For example, ETIS was used in the Texas and Louisiana Gulf Coast region to assist with the evacuation of almost 400,000 people as Hurricane Lili approached the region in October 2002. As one FEMA Region 6 Hurricane Program Manager noted, "Deploying the ETIS technology during the approach of Hurricane Lili allowed us for the first time to gather more evacuation information in one place than had ever been possible before. Information is power in a crisis situation, and Hurricane Lili gave us a glimpse of the future, where information will help avoid traffic jams that endanger the progress of emergency evacuations."
"The ETIS program, used in conjunction with a DOT/FEMA organized Evacuation Liaison Team, is designed to be useful in helping State and local managers anticipate State-to-State traffic."
U.S. DOT continues to refine ETIS with additional query capabilities on the available data in the system. During visits to Florida and Mississippi as part of this study, both States expressed their support for ETIS as a valuable tool. In addition, they recommended that U.S. DOT continue to refine ETIS to make traffic data more real-time and easier for States to upload through automatic links with the State's Traffic Management Centers.
Analytical Tools for Transportation Modeling and Analysis Flow Model
NETVAC was developed by Dr. Yossi Sheffi, Dr. Hani S. Mahmassani, and Dr. W.B. Powell at the Massachusetts Institute of Technology in 1982 as part of the reaction to the Three-Mile Island nuclear reactor incident in 1979. While strong in terms of a response to a Point-A-to-Point-B situation, it is limited in application to hurricane evacuation, which often include multiple Points A and B. However, transportation and emergency managers may seek to use this model to analyze route selection, intersection controls, and lane management.
MASSVAC followed NETVAC in development by Antoine G. Hobeika and Changkyun Kim in 1985, "as a simulation model designed for the analysis and evaluation of evacuation plans for urban areas threatened by natural disasters," including floods, hurricanes, tsunamis, and other related events. It is capable of simulating the flow on highway networks and identifying the available efficient routes from a hazard area to the nearest shelters and calculating the evacuation time for the network. It also considers traffic flow at the county macro-level, and "has been used in several applications, including a test of operational strategies for hurricane evacuations in Virginia."
In the mid 1990s, the Department of Energy's Oak Ridge National Laboratories Center for Transportation Analysis developed the OREMS, "to simulate traffic flow during various defense-oriented emergency evacuations." OREMS is based upon approved FHWA models and has been deployed to several State DOTs and other user communities, although not empirically validated by the developers in a hurricane evacuation event. OREMS is a probabilistic model that uses network characteristics that, while improved with local knowledge, can be produced with baseline data inputs. Like NETVAC, OREMS shows how a solution for one homeland security problem (terrorist incident) can be cross-applied to another (hurricanes). OREMS takes a consequence management approach, and "encompasses those measures aimed at alleviating the physical, socio-economic, and psychological effects" of an evacuation event. The addition of these factors to transportation network models provides a more dynamic model for evacuation planners. The developers of OREMS see it as only a step in the process to create an intelligent consequence management (ICM) system, which would be able to leverage real-time data using wireless networks, ITS, and GIS information. While the original OREMS can use a baseline data input, the more detailed "local" knowledge (e.g., traffic controller, road construction and maintenance status, etc.) will improve the alternatives for planners to consider. The benefit of this approach is that OREMS can produce a network analysis "on the fly," but it is improved with more detailed data input. The challenge of this systematic approach is that a great deal of data must be first inputted, tested, analyzed, and verified before it can become operationally useful, which is time-consuming and labor-intensive for users. However, in the long term, an ICM could prove useful to evacuation planners, including those at the U.S. DOT, with a tool that can handle large-scale evacuations.
In addition to nationally focused studies, the Gulf Coast States have invested in the study of models on their own. In April 2005, the University of Central Florida Center for Advanced Transportation Systems Simulation published a study for the Florida Department of Transportation (FDOT) that "investigated the relationships between a number of identifiable components that make up emergency evacuation, and how they can be integrated into a framework for modeling hurricane events." These new models will serve as a scientific basis for updated regional evacuation plans."