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Real-Time GIS Assists South Carolina in Managing Hurricane Floyd EvacuationArticle provided by Intergraph CorporationImplementing the Evacuation System "By far the most important data in the system is the traffic count information," said McEveen. "This tells us how many vehicles are moving through each lane per hour on most major arteries." The department has created an automated polling system from its Columbia headquarters whereby a computer calls each permanent counter by telephone five minutes past the hour to retrieve lane counts for the previous hour. During an evacuation, personnel are sent to the portable counters to read the tallies and verbally call them in to headquarters on cell phones. "The traffic counter totals are downloaded and entered into a standard Excel spreadsheet," said McElveen. "We used to generate various charts from the spreadsheet, and now GeoMedia Web Map extracts the counts directly from Excel." The next most important map set in the system shows the officially designated Hurricane Evacuation Routes. These state highways are roads that have been chosen for their ability to carry large volumes of traffic out of the state's major coastal cities, towns, and resorts. SCDOT's Traffic Engineering Section maintains the digital map of these routes on the department's GIS, which was built with lntergraph's MGE software. Another very important map set in the system shows road closures and detours around the closures. This information was included in the system primarily for the use of the state police, which typically recommends or carries out the orders to shut down a road or bridge. Several formats were considered for presentation of these maps in the system, and eventually scanned road maps were chosen because those are the most familiar to police officers. The paper road maps were scanned and entered into GeoMedia Web Map as JPEG files. When a road is closed and a detour route is selected, an SCDOT GIS analyst color codes the roads involved and annotates them with names or other information as necessary. This map section is saved in a special menu on the Web site. SCDOT realized that road and traffic information was merely one variable in an evacuation and decided to have real-time weather data linked to the system. This would allow government officials to compare evacuation progress with the advance of storm elements and modify the plan accordingly, either speeding it up or calling it off depending on hurricane activity. The system can handle 24 different data formats that are often used to transmit weather data including JPEG, TIF, GIF, BMP, GeoTIFF, RLE, and COT. This weather data can be displayed as desired on screen as an overlay on the evacuation and detour maps. GeoMedia Web Map registers the weather maps regardless of format to the state transportation maps. The weather data is also time linked with traffic count data and stored in the system so that officials can later review the interaction between wind, rain and traffic. Contents
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