Hurricane Evacuation Zones

Evacuation Zone Maps

Mass evacuations out of the path of hurricanes are conducted by emergency management agencies in coordination with hurricane forecasters. Evacuation zone boundaries are determined by local emergency management based on the Hurricane Evacuation Studies performed by the US Army Corps of Engineers, themselves based on the second-level maximum surge heights composites (Maximum of Maximums) from the SLOSH storm surge model runs.

Below is an example of the hurricane evacuation zone map for the greater five-county Galveston-Houston area for use during the 2009 hurricane season. A new map is issued by the emergency management agencies in May or June of each year, at the beginning of each new hurricane season, and the old one is discarded.

In most regions, local jurisdictions are divided into geographical evacuation zones; these are usually labelled with numbers, "1," "2," "3," etc., or letters, "A," "B," "C," although naming conventions vary by region. In the Galveston-Houston example, evacuation zones are labeled as "Coastal," "A," "B," and "C". However named, the zones delineate which populations would have to be evacuated en masse under which circumstances.

2011 Hurricane evacuation zone map for greater Galveston-Houston area

These zone lables have the added beneficial effect of offering the public an easily-remembered area identifier, such that local residents can easily determine during a hurricane threat whether an evacuation order has been directed toward them. A few years ago, the Galveston-Houston area adopted this procedure of drawing each evacuation zone to encompass a distinct group of zip codes, making it even easier for people to determine which zone they live in.

Phased Evacuations

A phased evacuation is one in which the different zones within a region are evacuated at different times, in stages, to avoid traffic congestion on the exit routes.

The process is much like evacuating an airplane during an emergency, but one in which the danger is coming from behind and the rear exit routes are blocked off. In such a case, passengers seated in the forward areas may be asked to stay in place until those behind them have had a chance to file past, to avoid congestion in the aisles.

Phased hurricane evacuations begin with those in the coastside areas, those who live closest to the danger of the sea, being asked to evacuate first. In this example, evacuation would begin with the barrier island of Galveston and beachfront or bayfront areas of the mainland, and proceed inland from there. It could continue all the way into southeastern Houston, some 50 miles inland, depending on the severity of the threat.

People in those locations in the near-inland are asked to remain in place just long enough to allow time for those seaward of them to move past, in order to avoid congestion in the roadways. Phased evacuation has become a necessity in some regions as a result of the pressure that escalating development and population increases has placed on transportation infrastructures in hurricane-prone areas.

Previous Page - Surge Heights
Back to Tutorial Home
Back to Home

Printer-friendly page