Public Works and Hurricane Evacuation

Craig E. Colten, Ph.D.

Carl O. Sauer Professor Louisiana State University, Baton Rouge, Louisiana Member, PWHS Board of Trustees

n recent years the world has watched in amazement as coastal cities in the United States have attempted massive evacuations in the face of impending hurricanes. Over a million fled the LouisianaMississippi coastal areas before Katrina made landfall in 2005. That same summer Rita inspired a massive exodus from large portions of the Houston metropolitan area that ended in unprecedented traffic snarls. When Irene approached the metropolitan centers of the eastern seaboard in 2010, evacuation for selected portions of Megalopolis was encouraged and confusion ensued. Despite the limits of the transportation networks and public misunderstandings of who needs to flee, evacuation via public thoroughfares remains a cornerstone of public safety.

The history behind hurricane evacuation is closely tied to the transportation infrastructure, meteorological forecasting, and customary practices that have evolved over the last century. During the first half of the twentieth century, predicting the paths of tropical cyclones was much less precise than it is today. With far less advance notice, the Weather Bureau would hoist storm warnings flags as the threat of a disturbance approached the coast—seldom more than a day in advance. Evacuation was a common response among the people living on the barrier islands of the eastern seaboard and gulf coast and in the communities in Louisiana’s coastal marshes. As the 1915 hurricane bore down on the Louisiana coast, a sizable number of people evacuated from communities in the wetlands down river from New Orleans. They could travel by train or personal transportation if they had the means to do so. Not all could afford to travel, and as a consequence the storm surge that inundated the region left a number of fatalities. Low population densities in the coastal regions were the most effective mitigation practice and minimized the burden on the limited transportation facilities available at the time.

Before mid-century, personal responsibility for evacuation via either public thoroughfares or on private transit remained the framework for evacuation. The rise of civil defense after World War II and passage of disaster relief legislation in 1950 led to the formalization of public plans for evacuation from tropical cyclones and other threats— such as a nuclear attack. These plans relied on existing transportation networks. In coastal areas narrow causeways typically connected barrier islands to the mainland and presented potential bottlenecks. Again, low populations in the highly exposed coastal areas minimized the threat of serious consequences that these choke points could cause.

Given the inability to provide accurate long-term forecasts, civil defense planners relied on in-place evacuation by sheltering people near their homes. Local plans designated sturdy, multi-story schools as shelters. In a city like New Orleans, for example, there were 167 shelters, most within walking distance of residents. Proximity and redundancy reduced the advance warning time necessary and eliminated pressure on the pre-interstate highways to accommodate long-distance evacuation.

A series of major hurricanes struck the U.S. coasts in the mid1950s and highlighted several emerging concerns. Increasing recreational development that brought tourists to the coastal areas during a portion of the hurricane season, with little additional development of transportation infrastructure, exposed increasing numbers of people with little hurricane experience to storms. Also, rapid urbanization in coastal cities like Miami and Houston placed additional demands on transportation networks. To contend with these issues, the U.S. Department of Commerce oversaw a national hurricane research project. It produced a model hurricane plan for coastal communities that called for development of detailed evacuation plans. As part of that effort, states designated particular roadways as hurricane evacuation routes and erected signs to help guide drivers in the event of an evacuation order.

Despite this effort, calamities continued to occur as local

residents resisted evacuation. When Hurricane Audrey hit the southeast Louisiana coast in 1957, many local inhabitants opted to ride out the storm in their low-lying homes. At least 500 perished due to the 10-feetplus surge that demolished homes and businesses across the chenier plains of Cameron Parish.

During the 1960s development of the interstate highway system offered hope for more efficient movement of large numbers of auto-bound evacuees—at least from the major cities. Barrier islands and coastal wetlands were largely unconnected to these new highways, and the causeways that linked seaside communities to inland freeways remained an inevitable point of congestion. For cities like New Orleans, the interstate highways greatly augmented the city’s routes of evacuation. I-10 offered paths of escape both to the east and to the west. In addition, the 1950s-era causeway across Lake Pontchartrain provided still another route directly to the north. Yet, each of these highways passed over open water, which in the event of storm would have to be shut down as waves crashed over the elevated pavement. This situation demanded longer advance notice to launch a protracted evacuation process. So, as transportation systems improved, demands for longer notice from storm forecasters became commonplace.

Structural protections built around New Orleans after Hurricane Betsy in 1965 reconfigured the viability of the neighborhood schools as shelters option. Beginning immediately after Betsy flooded 40 percent of the city, the Corps of Engineers and local partners began building a series of massive levees surrounding portions of the urban area with the potential to capture and hold any surge that overtopped the barriers. This new system could cause flood depths in excess of 20 feet. This threat made in-place sheltering an unwise option. Coupled with the interstate highway system, evacuation planners turned to the auto-oriented long-distance evacuation option.

Hurricane Ivan provided the first dramatic test of the personal automobile-interstate highway evacuation model in coastal Louisiana in 2004. As the storm moved toward the coast from warm Gulf of Mexico, local officials called for an evacuation from Louisiana’s largest urban area. Over 600,000 responded and they jammed the highways, along with residents from the Mississippi shore who also fled the storm as it veered to the east. What was normally a 1.5-hour drive to Baton Rouge, became an eighthour ordeal on the highway that passes through miles of wetland and offers few exits and alternate routes.

Officials prudently adjusted the plans and developed a “contraflow” solution to congestion. As Katrina bore down on the Louisiana coast in 2005, crews redirected all interstate lanes on the three expressways in an outbound direction. This greatly reduced the time to Baton Rouge and points beyond and enabled over 800,000 to safely flee the city.

Yet, weeks later when Hurricane Rita threatened Houston, about 52 percent of the population of the Houston area attempted to evacuate—including up to 40 percent of the population in areas that did not need to flee. This surge of humanity, without the benefit of contraflow, overwhelmed the highways and the services along the roads. Consequently, many were stranded on the shoulders of the road as the storm approached. Since the powerful storms of 2005, recommendations have been made to deploy trains and buses to alleviate the crowded roads. Certainly, buses might help. But southern cities like Houston, New Orleans and Miami do not have the substantial public transit networks like a New York or Chicago that can move millions of people daily. People quite simply rely on personal transport and highways. The gridlock experienced during Rita did prompt more families to carpool when Ike approached the Texas coast in 2008, but once again there was massive congestion along the interstate highways.

Public officials ordered a limited evacuation of low-lying areas in New York as Hurricane Irene approached in 2010. They also planned to shut down the subway before landfall in order to avoid complications that might accompany flooding of the subterranean sections of the mass transit system. In addition, sections of New Jersey highways employed contraflow. So, even cities with effective mass transit systems face disruptions to normal traffic when tropical systems arrive.

Procedures for evacuating thinly settled barrier islands and coastal wetlands are not easily transferred to major metropolitan areas. Highways that can barely handle rush hour traffic become overwhelmed by mass evacuations. In both the Houston and New York situations, lack of awareness of what areas needed to evacuate complicated the process and contributed to an uncoordinated response. Effective communication and timely mobilization must supplement the limited transportation infrastructure.

Craig E. Colten can be reached at (225) 578-6180 or ccolten@lsu.edu.