Hurricane Irma: How do you safely evacuate 5.6 million people?

Traffic on the northbound lanes of Interstate 75 became noticeably more congested as Floridians evacuated the area ahead of Hurricane Irma in Punta Gorda, Florida on September 8, 2017. (Brian Blanco/Getty Images)

As Hurricane Irma buzzes closer to Florida, the state has issued evacuation orders for some 5.6 million people. One of the largest evacuation orders in U.S. history.

Evacuation orders cover several counties and a quarter of Florida's population. Traffic jams have turned some interstates into parking lots, and many areas are suffering from gasoline shortages, *** reported. Hotels in nearby states were full and hundreds of makeshift shelters were hastily erected for those who had nowhere to go during the storm.

, but how is it possible to safely evacuate so many people?

The key, it turns out, is a lot of preparation and planning, said Susan Cutter, director of the Hazard and Vulnerability Institute at the University of South Carolina "It's a very thought-out and systematic process of planning to get people out of harm's way and then planning to get people back home, and there's a lot of science behind that," Cote told Live Science. "This is not just a willful thing.

RELATED: Hurricane Irma Photos: Images of a Monster Storm Where will Hurricane Irma make landfall on the Florida Peninsula? Hurricane Irma: Everything you need to know about this monster storm, whether to evacuate

The question of whether to evacuate is not always clear-cut, as Hurricane Harvey revealed a few weeks ago. However, cities like Miami and Florida counties have been thinking about and planning for major hurricanes for some time, Carter said. The key to getting people safely out of the hurricane is to calculate based on local road networks. Figure out how long it takes people to leave an area, called clearance time; figure out exactly which areas face hazardous conditions; and the arrival of tropical strong winds, or those greater than 39 mph (63 km/h). Hurricane Irma is a massive Category 4 hurricane with tropical storm winds extending 185 miles (295 kilometers) from its center, meaning people need more preparation time to evacuate safely. [WATCH: The harrowing flight to Irma captured on time-lapse video]

“You don’t want a car to be driven in this kind of wind, and you certainly don’t want a car to be driving in this kind of wind. from the barrier island to the mainland," Chet said.

Using hazard data from traffic models, population data and flood/storm surge data, emergency planners might calculate, say, evacuations It takes 24 hours for the Florida Keys, where tropical winds can arrive 36 hours before a hurricane hits, meaning evacuations need to begin 60 hours before the storm surge risk peaks, Cutter said. In this example, that might mean reducing the amount of time a storm surge warning is issued based on the lead time provided by the National Hurricane Center (usually 48 hours) for a hurricane watch or warning before it is officially issued.

To alleviate traffic jams, emergency planners set up evacuation routes and zone maps for each organization, so many organizations, such as universities, set out days before The closure comes early, meaning many people have had time to leave the city in an area of ??Florida based on detailed research on everything from vacant homes to flood risk to the demographics of vulnerable populations to land use on a site-by-site basis. The Department of Transportation also has a hotline that callers can use to determine the best way out of the area.

(The number is (850) 414-4100 or (toll-free) (866) 374-FDOT (3368)). FL511 also has information on evacuation routes. Governor Rick Scott also set up a separate hotline to help people who are stuck get out of the hurricane in time.

Natural gas shortages are another issue, but in this case, Florida has activated a state of emergency, which helps prevent price gouging that could lead to gas shortages, *** News Reports, Small Actions

While the extent of Irma's punishing winds may be large, the area that must actually be evacuated is much smaller. Generally, most people leave the interior coast and head out inland from northern Florida. Cattell said there was no need for the hurricane to migrate to Virginia or New Jersey, blocking interstate highways. The National Oceanic and Atmospheric Administration-NASA satellite GOES-16 captured a geographical color image of Hurricane Irma passing over the eastern tip of Cuba at around 8 a.m. Eastern Time on September 8, 2017. (NOAA/CIRA) "KDSP" In South Florida, according to the Florida planning map, the evacuation areas on the storm surge planning map are divided into concentric rings A to E. The area in evacuation area A is coastal Areas most likely to experience flooding and inundation. Not all areas require evacuation. These areas typically do not evacuate due to high winds (basically all areas of Florida are affected by high winds). Building codes are thought to mitigate wind damage. Therefore, only those who are in vulnerable structures and are moving to sturdier structures should evacuate due to winds, Coote said, as long as someone has a safe place to travel that can withstand the hurricane , Nanni said that many people living in evacuation area A may not necessarily have to go to other cities or states to stay safe. He planned to spend the storm at his home on Wednesday. This is the most dangerous evacuation area A, but if His plans to move a few miles away to a safer location had to be done if the weather forecast didn't work. Instead, they can go somewhere in the same city or general area.

The vast majority are either staying with family and friends or flocking to local hotels.

"They just feel more comfortable in hotels and motels or with family and friends," Carter said.

However, the most vulnerable – those without strong social networks and without many financial means – will need shelter. Cutter said the sites, usually schools, are pre-determined by the Red Cross based on the threat of flooding, the wind resistance of the building, the availability of sanitation facilities such as toilets and showers, and space for food preparation facilities or food preparation tents. In addition, population modeling requires forecasting the number of people seeking refuge, which is partly based on past data and partly on the local population. Members of the 156th Aeromedical Evacuation Squadron provide safety and security for patients at the North Carolina Air National Guard's Lower Key Medical Center in Key West as a C-130 evacuates ahead of the arrival of Hurricane Irma on September 6. (Senior Airman Sonya Clark/Air National Guard)

Hundreds of shelters have been set up so far; these are available to people who have nowhere to go and should go to the one closest to them of refuge. They will likely fill up quickly, according to officials at state and local agencies. (The Federal Emergency Management Agency (FEMA) has a list of shelters for people under evacuation orders.) Shadow Evacuations and Vulnerable Populations "KDSP" In any evacuation, approximately 10 to 20 fleeing people choose to voluntarily evacuate but are not within the evacuation zone. They may not directly harm life and limb, but may simply conclude that it is too difficult to stay inside the animal