Threats of impending disastersâsuch as hurricanes, floods, volcanic eruptions, the movement of airborne hazardous material, or unstable conditions at nuclear power plantsâmay provide officials an opportunity to save lives by encouraging or mandating civilian evacuation. Evacuation has three basic components. First is the departure of people from a stricken or threatened area. Second are the temporary resettlement of evacuees, and the provision of shelter and resources to them. Third is the final return of evacuees to either their predisaster residences or alternative locations. Moving a population out of harm's way through evacuation can save lives and substantially reduce exposure to hazards. Evacuations, however, can create complex challenges for officials and emergency managers. For instance, officials need to time the evacuation accurately to ensure the impending disaster does not occur while people are evacuating. Evacuations can also be hazardous. According to some reports, more people died during the Hurricane Rita evacuation than from the actual hurricane. Officials also need to take into account individuals who lack adequate transportation or have special needs because these individuals generally require more time to prepare to evacuate and travel out of the area. In such cases, it may be safer to have the special-needs population remain in the area and "shelter in place." Over the years, congressional concern regarding the equity, timing, and execution of evacuations has increased. Much of this concern is attributable to the New Orleans evacuation during the 2005 hurricane season, which has spurred numerous changes in federal evacuation policy. In general, federal policy defers to the states to enact laws pertinent to evacuation. Using authority from state laws and local ordinances, state and local officials may suggest or require the evacuation of residents from homes and communities before certain catastrophes occur. Rather than taking the lead in evacuations, the federal government facilitates the evacuation process through federal statutes that authorize agency heads to use federal resources to assist in the evacuation of civilians. Brief descriptions of four federal authorities follow. The Robert T. Stafford Disaster and Relief Emergency Assistance Act (hereafter the Stafford Act) authorizes the President to direct the Secretary of Defense to use resources to perform necessary emergency work to preserve life and property. This may take place even before the President issues a major disaster or emergency declaration. The President may also issue the declaration before the incident to lessen or avert the threat of a catastrophe by providing assistance for "precautionary evacuations." As mentioned previously, the final component of an evacuation is the return of evacuees to their predisaster residences or, if needed, to alternative locations. As amended by the Post Katrina Emergency Management Reform Act of 2006 (hereafter the Post Katrina Act), Section 425 of the Stafford Act states that the President may provide transportation assistance to "relocate individuals displaced from their predisaster primary residences as a result of an incident ... or otherwise transported from their predisaster primary residences ... to and from alternative locations for short or long-term accommodation or to return an individual or household to their predisaster primary residence or alternative location, as determined by the President." Under this authority the role of the federal government has been expanded not only to assist in the removal of citizens, but also to return disaster victims, or to relocate them. Limited information exists on the implementation of this relatively new authority for the return of evacuees to their predisaster residences. The issue of returning evacuees to their residences will be addressed later in the report. Another way in which the federal government facilitates evacuations is through assigning roles and responsibilities to various federal agencies, states and localities, and nonprofit organizations. The National Response Framework (NRF), administered by the Federal Emergency Management Agency (FEMA) and the Department of Homeland Security (DHS), establishes the roles and responsibilities of federal and certain non-federal entities when incidents overwhelm state or local governments. For example, the NRF identifies state, local, and tribal governments as having the responsibility of "ordering the evacuation of persons from any portions of the state threatened by the incident, giving consideration to the requirements of special-needs populations and those with household pets or service animals." The NRF includes "Incident Annexes," which are documents that address specific hazard situations. One of the annexes, the Mass Evacuation Incident Annex, assigns DHS and FEMA the responsibility for coordinating mass evacuations. With the support of other federal agencies and nonprofit organizations, the Annex also provides overall guidance for integrating the efforts of federal, state, local, and tribal governments during the evacuation of large numbers of people. According to the Annex : Federal support to mass evacuation operations will be provided at the state/tribal level and scaled to the incident.... Regardless of the scale of the incident, coordination among numerous command entities will be required to carry out the major functions of evacuation operations. Established in 1985, FEMA's National Hurricane Program (NHP) helps protect communities from hurricane hazards through various projects and activities. The NHP also provides assistance to state and local agencies in developing hurricane evacuation plans. One of the ways this is achieved is through NHP's Hurricane Evacuation Studies (HES). HES helps states and localities determine the probable effects of a hurricane, identify appropriate shelters, and predict public response to a hurricane and hurricane advisories. NHP also conducts hazard and vulnerability analyses for coastal communities. Analyses include an assessment of a hurricane's impact, a review of existing roads and transportation systems, and an analysis of the population (e.g., demographic characteristics). The information gained from analyses helps communities determine evacuation zones (areas vulnerable to the hurricane), develop evacuation maps, and determine clearance times. Studies of evacuations have identified several techniques that can make evacuations more effective. For example, informing citizens about evacuation routes and shelter locations as part of a community preparedness activity can help reduce the amount of time a household takes to evacuate. Without this information, households are generally slow to react to an evacuation order. Making provisions, such as gasoline, portable restrooms, and water, available along the route can also positively influence the effectiveness of an evacuation. Having tow trucks along egress routes to move vehicles can also help to keep the roads clear. The use of hazard analyses and evacuation analyses may produce a more effective evacuation. Hazard analyses are used to identify areas susceptible to a hazard's impact. Evacuation analyses assess the size of the affected population and its capability to transport itself. Additionally, evacuation analyses help identify modes of transportation to be used in the evacuation and potential evacuation routes. These lessons were derived primarily from disasters and emergencies such as wildfires, hazardous material spills, and hurricanes that would not be categorized as large-scale or catastrophic incidents. The evacuations as a result of some of these incidents do not involve long-term displacement, or the need to evacuate a large population. Hurricanes Katrina and Rita, however, did offer lessons on large-scale evacuations. Hurricanes Katrina and Rita increased knowledge of evacuations from large-scale incidents. Studies and reports covering the evacuations prompted by Hurricane Katrina also found techniques that make evacuations more effective. In general, they stated that implementation of the evacuations of many of the individuals affected by Hurricane Katrina went relatively smoothly because of successful evacuation procedures. Some examples of these procedures include the use of traffic management techniques such as "contra-flow" (making the in-bound and out-bound lanes uni-directional), which proved to be very effective. The use of conference calls by emergency managers and traffic directors to coordinate evacuation efforts also produced positive results. However, reports also asserted that other aspects of the evacuations needed significant improvement. The evacuations of New Orleans and Jefferson Parish were particularly troublesome. In fact, they were so problematic that they tended to negatively shape public perception of the evacuations as a whole. One account that criticized the Hurricane Katrina and Rita evacuations said that the call to evacuate appeared to be "weak, bureaucratic, and confusing." Perhaps as a result of such criticisms, calls to evacuate during Hurricane Ike used stronger language to convey the seriousness of the event. It is unclear, however, if stronger language was more effective than other factors in getting individuals to heed notices to evacuate. Another factor that influenced the way in which people were evacuated for Hurricane Ike was the experience of gasoline shortages and gridlock. In some disasters, a phenomenon known as "shadow evacuation" takes place. Shadow evacuations consist of individuals leaving the area without being told to do so. During the Hurricane Rita evacuation, non-mandated departures burdened evacuation routes and created fuel shortages. In Hurricane Ike, efforts such as persuading individuals in non-evacuation zones not to leave and asking families not to evacuate in multiple vehicles helped reduce shadow evacuations. The Hurricane Katrina evacuations also underscored the significance of timing an evacuation. According to one view, large metropolitan areas generally need 48 hours to evacuate (for Louisiana, the preferred minimum amount of time to conduct a major evacuation is 72 hours). However, the earlier an evacuation is ordered, the greater the likelihood is that there will be an error in the weather forecast. The inability to predict a storm track compounds the difficulties of evacuation decision making. In the case of Hurricane Katrina, evacuations were declared late, or not at all, in two of Louisiana's most populous areas: New Orleans and Jefferson Parish. According to one congressional report, a more complete evacuation of these areas could have saved lives and reduced human suffering. Another congressional report concluded that the incomplete evacuation led to the need for a post-hurricane evacuation. Federal, state, and local officials had not anticipated the need for a second evacuation. As a consequence, problems in communication, lack of situational awareness, and a shortage of bus drivers resulted in poor implementation of the second evacuation.