Out of Harm's Way

By Craig Guillot

According to the U.S. Department of Transportation, more than 400 man-made or natural disasters every year require the evacuation of nearby residents. While wildfires and floods can often require mass movements of people, evacuations from hurricanes can turn into regional efforts that call for multiple jurisdictions to move hundreds of thousands, even millions, of citizens.

In October, as Hurricane Matthew bore down on the Southeastern U. S., some two million people had to flee. Experts say a good evacuation plan is one that efficiently moves people out of harm's way at just the right time. These plans should be built upon factbased models, evacuate residents in stages, have transportation plans to expedite the flow of traffic, and also have the flexibility to adjust to changing needs.

Most hurricane evacuation plans are designed to evacuate parts or all of a city or county within 48 to 72 hours. They often start with people who live closest to the coast or large bodies of water and are at high risk of wind damage and flooding. The primary challenge with evacuations is that they are not only difficult to plan but also difficult to call.

Dennis Smith, AICP, growth management coordinator for the Florida Department of Transportation, served as the group manager for evacuation planning and risk engineering at Atkins's Risk and Emergency Management division. In that role, Smith had participated in post-storm assessments with the U.S. Army Corps of Engineers and says evacuations are a "last resort" because there's an intrinsic danger of putting so many people on the road.

Most jurisdictions use models and forecasts from the National Hurricane Weather center to determine whether and when to evacuate. Smith says most plans are designed to measure scenarios and evacuate residents in stages based on risk profiles. "You want to ensure your recommendations are for the fewest number of people. ... You don't want to 'overevacuate' people because it may be safer for some to stay at home," says Smith.

Evacuations are typically measured in "clearance times," the time it takes to get all of the intended evacuees out of the area. The biggest challenge is congestion: limited roads in one direction, busy intersections at major thoroughfares, and crowded on-ramps to interstates.

Evacuations can also be more complex in tourist locations, and from South Padre Island, Texas, to Outer Banks, North Carolina, almost all at-risk coastal areas have high concentrations of tourists. Drew Pearson, director of emergency management for Dare County, North Carolina, says the county's population can spike from 40,000 to 300,000 on weekends. A local act was enacted years ago that mandated vacation renters to comply with mandatory evacuation orders.

The 2004 and 2005 hurricane seasons hit Florida with a record number of storms, impacting millions of residents all over the state. That is the last time Tampa was evacuated, during Hurricane Charley. Most people went to Orlando, northeast of Tampa, because of its abundant hotel space. But that many people going all the same direction, "puts a lot of pressure on our two main northsouth interstates," says Brady Smith, aicp, cfm, principal planner at the Tampa Bay Regional Planning Council.

After the 2004 and 2005 seasons, Florida lawmakers passed new laws that identified enhanced statewide hurricane evacuation planning. This called for more collaboration and planning between counties and state agencies. The state also funded regional evacuation studies and redefined coastal high-hazard areas as state priorities. The Florida Regional Evacuation Study Program was eventually produced in 2010 with eight volumes of studies documenting, analyzing, and making proposals for counties all over the state.

"It has allowed us to compare plans as apples to apples, where you use the same types of transportation modeling, same evacuation clearance times, same methods for determining demographics. It really gives us a better coordinated effort," says Smith.

Public information is a big part of it. We start with zip codes [along the coast] and tell others to stay put so that they can get out of harm's way. Then we move further up the chain, further away from the coast.
—STEPHAN GAGE, CHIEF TRANSPORTATION PLANNER, HOUSTON-GALVESTON AREA COUNCIL

A man walks through floods on East Battery Street as storm surge and rainwater from Hurricane Matthew hit Charleston, South Carolina, on October 8. Photo by Jonathan Drake/Reuters.

Moving in stages, contraflow

Since hurricanes lose so much of their power once they hit land, evacuations are often planned in sequential stages. Those directly on the coast and near large bodies of water face the greatest threat and are usually the first to be evacuated.

In a place like greater Houston, evacuating four million residents at once would create a week-long gridlock. Stephan Gage, chief transportation planner at the Houston-Galveston Area Council, says the region uses a number of zone maps to identify areas by the risks they face.

Because staged evacuations rely on the cooperation of citizens, public announcements are critical. Gage says the Texas Department of Transportation's Together Against the Weather program uses brochures, commercials, and local media to inform citizens about when and how to leave town if an evacuation is called.

"Public information is a big part of it. We start with zip codes [along the coast] and tell others to stay put so that they can get out of harm's way. Then we move further up the chain, further away from the coast," says Gage.

Brady Smith says putting too many people on the road at once can create so much traffic it may actually deter people from evacuating. Contraflow — where highway and interstate lanes are all converted in the same direction — can work, but only when carefully planned. When Houston attempted a last minute contraflow in 2005 for Hurricane Rita, it left motorists in 20-hour traffic jams with gas shortages and miles of gridlock, something a 2005 article in USA Today called a "highway horror." According to an article in the Houston Chronicle, state officials said roughly 400 miles of highway were "stitched together" little more than a day before the hurricane landed.

Gage says that after Rita, transportation planners developed contraflow plans for all major highways leading out of Houston. It remains a little-used option because while it can more quickly move people out of the vicinity, it usually just creates congestion farther down the road, says Gage.

Contraflow also requires significant law enforcement manpower from multiple jurisdictions to block off every interstate exit for miles. When westbound contraflow is enacted in Houston, I-10 becomes one way for nearly 160 miles, all the way from Brookshire to San Antonio. The Chronicle article said Houston's 2005 contraflow required an "army of local police" and the help of more than 1,300 Department of Public Safety troopers from around the state.

"It works, but it's sort of a method of last resort because it's very manpower intensive," says Gage, who notes that making sure people are following the rules of contraflow takes a lot of boots on the ground.

In the Houston-Galveston area, risk determines which zones will evacuate when. Source: Houston-Galveston Area Council.

A large electronic billboard urges people to evacuate Charleston, South Carolina, and the coastal areas before the arrival of Hurricane Matthew on October 7.

Vulnerable populations

John Renne, PhD, AICP, director of the Center for Urban and Environmental Solutions at Florida Atlantic University in Boca Raton, Florida, previously served in the Department of Planning and Urban Studies at the University of New Orleans. Renne, who personally evacuated during Hurricane Katrina in 2005, says planners also have to consider special needs populations such as those in hospitals, nursing homes, or without transportation.

Katrina brought national attention to the issue when thousands of the estimated 120,000 "carless" people were unable to leave town. There were originally plans to bus residents out of town but those plans were sidelined when roads were clogged with traffic.

Renne, who didn't own a vehicle, had rented one in advance to drive to Houston. But that option was only available for those with the funds and inclination to book in advance. At the last minute, carless residents were directed to the Superdome as a shelter of last resort, which resulted in its own humanitarian crisis. It took almost a week for the National Guard to help evacuate all people from the Superdome and government officials at the local, state, and federal levels were criticized afterward for poor planning.

"It was sad because there were people trying to leave town but just didn't have transportation. It really made me start thinking about carless transportation," says Renne.

Nearly three-quarters of those who died in Hurricane Katrina in New Orleans were over the age of 60 and almost half were over the age of 75. Renne later coauthored a study at the UNO on carless and special needs evacuation planning. It's an important aspect for emergency planners to think about. "Part of this learning should include mandatory evacuation plans for all cities that take into account the use of public transportation and to efficiently evacuate those with and without cars," says Renne in a post on Planetizen.

Using models

Making the call to evacuate is a difficult decision that, depending on the jurisdiction, can rest on the shoulders of a governor, mayor, city council, or emergency director. Evacuate too late and regions risk highway gridlock and putting lives in jeopardy. Evacuate too early and decision makers may realize such a move wasn't necessary, which can make residents pretty angry. Evacuation, says Dennis Smith, is a "very difficult decision" based on plans, projections from the National Hurricane Center, and buy-in from leaders.

Florida saw four major hurricanes in 2004 that required the evacuation of many communities multiple times. According to a report, 31 percent of the southeastern part of the state had evacuated at least twice, while in southwestern Florida many residents evacuated three or four times. Most who stayed said they did so because they felt their homes could withstand the storm. The study found that storm strength had a significant positive effect on the probability of evacuations.

Brady Smith says that while evacuations aren't common in Tampa Bay (the last major hurricane to hit the region was in 1926), there are still plans for getting people out of town. A major challenge, there and everywhere, is that no one can be quite sure exactly when and where a storm is going to strike. Hurricane forecasts are typically designed in a cone shape that narrows down in size the closer the storm gets to land. While a storm three days out may have a cone of certainty of a few hundred miles, that may be narrowed down to 100 miles by the time it's less than 24 hours from landfall. Some Tampa residents were evacuated in 2004 before Hurricane Charley made a sudden change in track.

Smith says that while there's a science to planning evacuations, "no one really knows" what a storm will do until the last minute. As a result, there are also a lot of behavioral elements that factor into how and when people evacuate. He says going years without a major storm can also lull residents into complacency. "Most people can't answer the question about where they would go or where they would evacuate to. After [a long time without a hurricane], it's out of sight, out of mind," says Smith.

When Hurricane Matthew struck Florida and the East Coast in early October, nearly two million people were evacuated, including 1.5 million in Florida and 175,000 in coastal South Carolina. John Renne said while highways were largely orderly and efficient, there were a number of media reports that some people were refusing to evacuate.

"There was a lot of complacency among some people as many had never been here when a storm hit. It ended up not being that bad but could have been much worse. We dodged a bullet," said Renne.

Peter Neilley, senior vice president of global forecasting services at The Weather Company, said in a column that "overall, hurricane forecasts are clearly getting better" with less error. But, while forecasters can now better predict the direction of a storm, they can't always forecast its strength, something that can impact the need for evacuations. These storms can often quickly gain or lose strength in less than a day. Neilley says a "useful forecast" is hard to define because it's ultimately a personal decision on how to respond.

Unfortunately, one of the best ways to enhance an evacuation plan is "to actually go through one" and then discover its weaknesses, says Renne.

He says that another problem is that while there is a framework to deal with post-disaster recovery, there is no national policy or framework for proactive planning. Although Florida has funding and organization at the statewide level to help jurisdictions plan for evacuations, most states leave it to the locals.

"It comes down to every local government for themselves, figuring out how they can go about planning," Renne says. "There are no standards or guidelines to say what it should look like."

Craig Guillot is a business reporter based in New Orleans.

Resources

National Hurricane Center: Hurricane Preparedness — Be Ready nhc.noaa.gov/prepare/ready.php.

Houston-Galveston Area Council, Hurricane Evacuation Planning: h-gac.com/taq/hurricane.

New Orleans Hurricane Readiness and Evacuation: www.nola.gov/ready.

Florida Regional Evacuation Studies: floridadisaster.org/res.