One of the more critical, though commonly overlooked, aspects of transportation planning and management is evacuation. This is not surprising since evacuations have largely been viewed as a regional issue with a low probability of occurrence. Over the last five years, however, homeland security concerns and the problems associated with several evacuations have brought more attention to the need to improve evacuation planning and management, a subject that has been overlooked within the transportation community. But this view is changing.
Look this way
Reliance on highway-based evacuations has grown over the years. Prior to the construction of the interstate system, there were limited means to move people out of major population centers and few places to shelter them once they did. As a result, sheltering in-place was the most common method of early civil protection. More systematic approaches to evacuation planning developed during the Cold War in response to the threat of nuclear attack and grew more sophisticated in the ’60s and ’70s to protect against nuclear power plant accidents. Hurricane evacuation planning also advanced during this period as satellite meteorology gave weather forecasters the ability to track storms several days out to sea. In more recent times, the application of computer modeling and geographic information systems (GIS) have been used to analyze the traffic conditions associated with cross-state evacuations.
Despite these advances, the subject of evacuation has been a widely overlooked issue within the transportation field. The reasons for this are numerous. First, evacuations are infrequent events and most urban centers of the U.S. have never evacuated. Even coastal cities like Miami, New Orleans and Houston, which are prime threat areas for hurricanes, only evacuate once every 10-20 years.
Evacuations have generally been a regional phenomenon, associated with hurricanes in the southeast and occasional wildfires in the western U.S. The combination of these factors has meant that most transportation agencies have not been willing to allocate significant resources to support evacuation planning. Given the struggles of DOTs to keep pace with routine needs of highway maintenance, capacity and safety, it is difficult for them to justify the expenditure of limited resources on a problem that is likely to arise once or twice in a generation.
Though they may be infrequent, the risk of not preparing for evacuations can be devastating. Evacuations have the potential to directly improve the safety of more people than any other single transportation scenario. In New Orleans, where the local topography virtually assures the inundation of the entire metropolitan area in most medium to strong hurricanes, a full evacuation of the area is a necessity and the price of not doing so could be measured in thousands of lives.
It also is suspected that most DOTs have had a general lack of understanding of evacuation processes and issues. Historically, evacuation preparedness has been an emergency management/law enforcement issue with transportation agencies providing peripheral support. As a result they have not become familiar with the needs of evacuation. Transportation agencies also have viewed evacuation problems as a simple demand-in-excess-of-capacity issue that they were able to do little to improve, short of constructing entirely new roadways. In reality, however, there are relatively inexpensive and simple methods that transportation agencies can and are using to improve the efficiency and effectiveness of evacuations.
Floyd the teacher
A general conclusion that was reached after the most recent series of evacuations was that transportation and emergency management officials were not as well prepared for the mass movement of threatened populations as they had assumed. Deficiencies were recognized in many areas, both transportation and non-transportation related. Some of the reasons for the problems seen in Hurricane Floyd have been attributed to the unique nature of the storm and the memory of the damage caused by other recent storms. Regardless of the reasons, causes or who had responsibility for them, the Floyd experience showed that the nature of evacuations appears to be fundamentally changing. The following sections highlight several of the most critical of these issues and briefly highlight how they are being dealt with.
Limiting evacuation travel demand
Perhaps the most significant issue associated with evacuation is the need to control travel demand. With coastal populations increasing rapidly compared to the number of evacuation routes, the need to limit the number of evacuees on the road becomes essential. Most emergency management officials agree that there is not enough roadway capacity or mass transit assets to completely evacuate major metropolitan population centers, like New Orleans or Miami, in two or three days.
A contributing problem is evacuation over-response, or “shadow evacuation.” Shadow evacuation occurs when people receive incorrect information or overreact to a threat. During Floyd the Florida Division of Emergency Management estimated that about 35% of the approximately 2 million evacuees that were on the road in that state did not need to leave. Shadow evacuations are problematic because they may prevent truly threatened populations from leaving and can occupy limited transportation resources. Thus, it is necessary to move the most critically threatened people by controlling when and where people evacuate.
Evacuation demand has a significant effect on the speed and efficiency of evacuations. One of the ways that officials are working to limit demand is through better public information and education programs, including educating the public about which areas are truly at risk and by working with the news media to give more accurate descriptions of threat levels. Other demand limitation techniques involve strengthening building codes and the use of in-place sheltering practices that diminish the need for people to evacuate.
Maximizing transportation infrastructure
The counterpart to limiting demand is the maximization of available transportation infrastructure. While this seems obvious, it is a concept that has not been fully taken advantage of in recent evacuations. A technique to increase evacuation capacity that has grown in popularity since Floyd is the use of contraflow freeway segments. Contraflow evacuation strategies involve the reversal of one or more lanes and or shoulders in the inbound direction for use by outbound traffic. Preliminary studies have shown that such techniques have the potential to increase outbound flow volume by about 70%. Other planned methods of infrastructure maximization include more effective use of parallel non-freeway evacuation routes (through the coordination of traffic control), the use of mass transit systems and the implementation of policies to limit interruptions to evacuation flow at railroad crossings and drawbridges.
Improved communication/data exchange
The most often cited need by transportation officials involved in past evacuations was the need for better communication. Numerous instances were cited in which communication gaps occurred between the various emergency management, transportation and law enforcement agencies involved in evacuations. Just as significant were communication difficulties with the public. Many states are working to combine emergency management personnel resources into single facilities and are working jointly to establish evacuation policies. Emergency officials in Florida now have agreements with the state’s network of public radio stations to broadcast traffic and sheltering information during evacuations.
Another communication-related issue is the need to collect and transfer traffic information during an evacuation. Traffic information is critical for the strategic management of evacuation routes and the allocation of transportation resources to most effectively address the current needs. During the Georges and Floyd evacuations, access to accurate and timely traffic information in most states was difficult. Emergency management officials often found themselves “working blind,” with little quantitative knowledge of which evacuation routes were flowing well and which were in gridlock. As a result, they were unable to redirect traffic from routes that were over capacity to nearby roads that were carrying little traffic.
While the most important information includes traffic flow rates and speeds, other critical information includes the location of incidents that block lanes or slow traffic and weather conditions and flood levels. One obvious way states are addressing these needs is through the application of ITS technologies. One of the problems with existing ITS technologies is that they tend to be concentrated in urban areas while the majority of evacuation travel takes place in rural areas.
One system currently in test deployment seeks to address the lack of rural ITS resources. It is the Louisiana Department of Transportation and Development’s (LaDOTD) traffic/weather/flooded road alert system. The LaDOTD system combines traffic data recorders with the U.S. Geological Survey’s (USGS) Louisiana HydroWatch stream monitoring stations at critical locations. When operational these combined stations will have the ability to collect traffic, weather, flood and bridge scour data on key evacuation routes in the southern third of the state and transfer this data to the state emergency operations center via satellite. Some additional advantages of the system are that it will not require additional major capital investment (since most of the basic infrastructure is already in place), retraining of field personnel or additional land-based utility services. Another advantage that it has over most similar systems is that it will transfer data via the Geostationary Operational Environmental Satellites (GOES). Thus, the information will be available nearly instantaneously and will be accessible regardless of the weather conditions.
Enhanced coordination for regional and cross-state evacuations
The crossing of political boundaries, both within and between states, is another critical issue that also is being addressed. Jurisdictional boundary issues can be particularly complicated in locations where contraflow operations are planned. Until recently, little regional hurricane evacuation planning was done. This was primarily because evacuations are ordered on a more localized, county-by-county basis. In Florida, the DOT found that a lack of coordination between counties resulted in congestion as evacuations intersected one another and traffic from one county was evacuated onto the already-crowded evacuation routes of a neighboring county. Increasing coastal populations also have meant that the potential for region-wide evacuations (involving substantially higher numbers of people) has increased. Because of this, states like Florida are working to address these types of problems as part of their statewide evacuation programs.
Another example of more recent regional evacuation coordination can be seen at the metropolitan planning organization (MPO) level. The Metropolitan Washington Council of Governments (COG) along with the state of Maryland, the Commonwealth of Virginia, the federal government, public agencies, the private sector and volunteer organizations, and local schools and universities has developed a “Regional Emergency Coordination Plan (RECP).” The RECP provides a mechanism for collaboration in planning, communication, information sharing and coordination activities before, during or after regional emergencies. The transportation function of the plan focuses on disruptions to the regional transportation system resulting from surges in demand and emergency response needs that require interjurisdictional coordination and information sharing.
Interstate evacuation coordination also is critical. A major state-to-state overlap of interstate evacuation traffic occurred during Hurricane Floyd in 1999. During the Floyd evacuation, traffic from both Florida and Georgia contributed to the congestion on evacuation routes in South Carolina. To reduce the potential for similar problems in the future the South Carolina, Georgia and Florida DOTs are working together to correct these deficiencies. Interstate regional plans will now consider interstate contraflow and the use of secondary highways to keep local traffic off interstate routes whenever possible.
Another critical location is the I-59 border crossing between Louisiana and Mississippi. The existing road network and geography of New Orleans force a significant percentage of Louisiana evacuees into Mississippi. Thus, the current evacuation proposal seeks to contraflow all lanes of I-10 eastbound out of New Orleans and on to northbound I-59 into Mississippi. However, since such a plan could significantly impede Mississippi’s ability to serve the needs of its own citizens, negotiations are under way to resolve this issue.
Improved evacuation of low-mobility groups
Transportation infrastructure in the U.S. has developed to serve vehicular traffic. While reliance on personal transportation works reasonably well under routine conditions, it can cause significant challenges for emergency management officials. The number of people without access to transportation in New Orleans has been estimated as high as 25-30% of the population and includes over a quarter million people. In addition to people without vehicles, potential evacuees can include the indigent, elderly, prisoners, the infirm and tourists. Evacuation of these low-mobility and special needs groups is an area that, while included in most state emergency operation plans, has been largely unaddressed by DOTs.
Busing has been the most common mode of transportation for low-mobility groups, and in the past emergency management agencies have contracted with local transit authorities, school districts and tour operators with varying levels of success. However, many heavily populated cities do not have a sufficient supply of buses to move all low-mobility evacuees. The total number of buses in all of New Orleans would provide only a fraction of the capacity needed to transport all of these people. To counter this problem, Louisiana emergency management officials are working through local churches to encourage “good neighbor” strategies in which neighbors with means of transportation would assist those without during an evacuation.
Work zones on evacuation routes
Another commonly overlooked issue in evacuation planning and preparedness has been highway work zones. In 1998, during the evacuation for Hurricane Georges, Alabama, Mississippi and Louisiana each had construction zones on evacuation routes. Recognition of this situation permitted DOT officials to request the contractor clear construction equipment and open partially constructed lanes to outbound traffic. Through this quick action delays were minimized. However, less than a year later, similar problems of construction on evacuation routes also were experienced in North Carolina during Hurricane Floyd.
Not just in case of emergencies
Recently, organizations like FHWA and the Transportation Research Board (TRB) have recognized the importance of evacuation and have been supporting the development of initiatives to address some of the needs described above.
In the spring of 2002, the FHWA awarded a number of grants to states to enhance the collaboration between state DOT and emergency management agencies to jointly identify transportation needs and resources. Some of these have been used to support projects such as the integration of real-time weather and traffic information with state emergency operations centers and traffic operation centers, and improved public information about evacuation routes and procedures.
In response to the events of Sept. 11, the FHWA also hosted a series of workshops focused on transportation response to and recovery from major events, with particular emphasis on those that give little or no advance warning time, such as terrorist attacks. Similar efforts are under way for both transit and freight operations. One of the key goals of the hurricane evacuation and transportation operations security programs at the FHWA is to increase the understanding and interaction among emergency management, first responders and the transportation community. The simple knowledge of whom to call and available resources can make the difference for effective emergency evacuations.
TRB also is supporting efforts to coordinate and disseminate evacuation-related research information. The TRB Subcommittee on Emergency Evacuation ANB10(3) was founded within the committee on Transportation Safety Management. Its membership includes a number of transportation professionals in the private and public sectors that are involved in the design, planning, management, operation, enforcement and research of transportation resources for evacuation. Over the long term it is hoped that efforts such as these can become the catalyst to significantly increase both the interest in and research funding available to evacuation-related transportation issues.
Finally, it is important to keep in mind that the new information generated and techniques planned for use in evacuations have application beyond emergency-specific conditions. These operational strategies are directly applicable to the management of traffic associated with a variety of high-demand events, including sporting events, concerts and festivals, and particularly in areas that have limited network capacity. The use of reversible lanes, coordination and restriction of turning movements, temporal and spatial demand phasing, and other techniques common to law enforcement and emergency management groups can be useful to reduce the daily congestion associated with morning and evening commuter traffic. TME
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