September?s great escape

Oct. 4, 2001
The month of September means the height of hurricane season for those who live along the coastal areas of the Southeast and the

The month of September means the height of hurricane season for those who live along the coastal areas of the Southeast and the Gulf of Mexico

The month of September means the height of hurricane season for those who live along the coastal areas of the Southeast and the

The month of September means the height of hurricane season for those who live along the coastal areas of the Southeast and the Gulf of Mexico—the time when a major storm is most likely to strike land. And as more and more U.S. citizens find themselves living along the coast or close to coastal areas, the threat of significant loss of property, and even lives, increases with the passing of summer.

Fortunately, weather forecasters have become more adept and more precise in predicting the eventual path of hurricanes, giving residents and emergency centers a better chance of getting out of the way when a serious storm is threatening. But there are times during hurricane season when anticipating traffic flow can be just as critical as predicting landfall.

This responsibility falls primarily to state officials—representatives of departments of transportation, highway patrols and emergency-preparedness staffs—who convene in emergency operation centers in each state and coordinate activities with county and local managers.

Forecasting demand

While emergency-response personnel at all levels have access to detailed forecasts of landfall, intensity and likely evacuation times thanks to the HURREVAC storm-tracking software maintained by the Federal Emergency Management Agency (FEMA), until this year the ability to anticipate traffic flow resulting from mass evacuations did not exist.

As a result, state emergency-response centers have been unprepared for the problems that result from large numbers of residents crossing state lines in search of safety and shelter. This was precisely the case with Hurricane Floyd, which threatened the Carolinas in September 1999 with storm surges over 10 ft and wind gusts up to 120 mph.

While the storm eventually turned to the northeast and traveled up the East Coast, rainfall as high as 20 in. caused widespread flooding in the Southeast, resulting in 50 of the reported 56 deaths associated with the storm and as much as $6 billion in damages, according to the National Hurricane Center.

Floyd also provoked the largest evacuation effort in U.S. history, sending more than 3 million residents of Florida, Georgia, South Carolina and North Carolina to the highways in search of safety and shelter.

The resulting traffic snarl had some residents trapped inside their vehicles for as long as 24 hours without the availability of restrooms, gas stations or food services. The mass exodus associated with Floyd also immediately filled temporary shelters and overwhelmed the ability of state and local officials to manage or respond to widespread gridlock.

With more than 55 million Americans threatened every year by the destructive force of nature’s most fearsome storms, FEMA, the U.S. Department of Transportation (U.S. DOT) and the U.S. Army Corps of Engineers all took the evacuation associated with Hurricane Floyd as a wake-up call.

The agency immediately began putting into place plans for an Internet-based information system that would allow state and county officials to better anticipate the traffic heading their way and prepare temporary shelters and other facilities required during a massive hurricane event.

Predicting evacuation behavior

For assistance, FEMA called on PBS&J, a design and engineering firm based in Miami, Fla., with a considerable track record in hurricane evacuation expertise. In all, PBS&J has conducted more than 30 studies in the Southeastern U.S., including storm-surge mapping, clearance-time reporting and evaluations of post-storm evacuations.

To better understand and predict the response of populations living in hazardous zones along the East Coast, PBS&J, working with the Corps of Engineers, asked the country’s foremost expert on hurricane evacuation behavior, Dr. Earl "Jay" Baker, a professor of geography at Florida State University, Tallahassee, Fla., to undertake the largest post-storm evaluation ever conducted for the federal government.

Baker’s firm, Hazards Management Group Inc., interviewed more than 6,900 individuals living in counties along the coasts of Florida, Georgia, South Carolina and North Carolina. The firm’s analysis showed a 90% evacuation rate in some counties and the highest percentage ever recorded for out-of-county destinations from areas not expected to receive a direct hit from the storm itself or from storm surges.

In the case of Hurricane Floyd, for example, among the highways most severely affected were I-26 heading northwest from Charleston, S.C., I-16 heading northwest from Savannah, Ga., and I-10 heading west from Jacksonville, Fla.

This high percentage of residents willing to evacuate based on storm predictions could indicate the growing success of weather forecasters in tracking storm patterns more precisely and communicating storm dangers more specifically and to a more receptive audience.

Most useful in building an information system designed to deal with future evacuation demands, however, were the results of the Hazards Management Group study that identified evacuation destinations. This information, along with previous studies conducted by PBS&J, formed the basis of an Internet-based model capable of forecasting traffic demands and, more specifically, state-to-state traffic flows.

Real-time emergency management

With the hurricane evacuation studies forming an extensive database, PBS&J called on its Geographic Information Systems (GIS) group to help build a model using specially designed algorithms that incorporate current data to display information useful to each state’s emergency managers in the form of tables and roadway network maps.

Users can input, for example, information such as hurricane category, expected evacuation rate and tourist occupancy percentages. A table then will predict state-to-state traffic flows and specific destinations by number of vehicles. This is especially valuable to emergency managers previously unable to anticipate traffic originating in neighboring states and therefore ill-equipped to notify local personnel.

The system’s software also is capable of translating this information into a series of roadway network maps that display anticipated congestion levels by color and line size. This function allows emergency managers to compare expected traffic volume with directional capacity and, if necessary, alter the lane usage of specific roadways either by number of lanes or direction.

As a result of PBS&J’s post-storm evacuation studies, for example, officials in South Carolina already have put into place a contingency plan to convert I-26 heading northwest from Charleston from two lanes in each direction to four lanes heading away from the coast and the threat of landfall.

Because the system is Internet-based, projections also are capable of responding to real-time changes in the data. As users update information or create changes in traffic patterns resulting from emergency management decisions, the implications for neighboring states become immediately available. As a result, communication across state lines, a key objective identified by FEMA, is greatly enhanced.

The system will allow, for example, officials in Georgia to better anticipate traffic heading north from Florida and make timely decisions on the management of specific traffic interchanges and highway on-ramps.

In November 2000, the system was beta-tested during a mock evacuation exercise held in Atlanta. Participants included emergency managers from Florida, Georgia, South Carolina, North Carolina, Alabama and Mississippi as well as representatives from FEMA, U.S. DOT and the Corps of Engineers.

The system was judged a success, with participants noting especially its user-friendliness.

"We have now given states a new tool to better anticipate traffic headed their way in a major storm event," said FEMA Hurricane Program Manager Bill Massey. "At the same time, we have begun to foster a level of communication and coordination between states that has never existed before."

Extending the system

With software located on a server in PBS&J’s Tallahassee office, the Evacuation Traffic Information System (ETIS) continues to undergo refinements and enhancements.

The mock evacuation exercise, for example, led to the permanent establishment of an Evacuation Liaison Team—comprising a GIS specialist and representatives from FEMA and the U.S. DOT—to support affected states and ensure they are entering information into the traffic-demand model.

With Louisiana joining the system this year, plans already are in place to eventually include Texas, Virginia and Delaware as well. Also, ETIS software is scheduled for installation on a federal server based in Washington, D.C., with a system backup stored at PBS&J’s Tallahassee office.

Although access to the system currently is limited to state emergency operation centers, another enhancement planned for next year is to make screen views available to all county emergency centers in states that are a part of the system. System managers also are developing direct linkages to HURREVAC software.

In another important development, PBS&J’s intelligent transportation systems specialists have been investigating technology that can be deployed by states to maximize the advantages of a real-time emergency forecast system.

Both Florida and South Carolina have begun to consider linking automatic traffic counters to ETIS, and other states are looking into a variety of strategies, including the ability to remotely convert two-way traffic to one-way, thereby doubling the number of lanes available on affected routes.

The system’s GIS component also contains the possibility for a host of future enhancements, including the overlay of shelter locations, lodging availability and other crucial information.

Finally, efforts are being made to further streamline the system’s user interface so that emergency managers, who may interact with the system only once or twice a year, can easily have access to a critical tool without significant interference.

Ready for September

What began as a response to an unanticipated crisis has now become the foundation for a wide-reaching, emergency management tool that already has won praise from the engineering profession and promises to become the standard against which the development of emergency management technology will be evaluated.

In recognition of that achievement, the ETIS program was honored by both the Florida Institute of Consulting Engineers with its 2001 Engineering Excellence Award and by the American Society of Civil Engineers.

Based on an extensive behavioral database, ETIS offers users a high degree of reliability in both monitoring and forecasting real-time traffic. With software continuing to be enhanced and communications between states continuing to expand, the system also promises adaptability in its functions and the precision of its information.

The results of this development involving behavioral analysis, information-system evolution and interagency coordination will now provide emergency managers with a capability similar to the growing sophistication of storm-forecasting technologies, allowing precise and timely management of hurricane threats both off- and onshore.

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