DEEP DETAIL. Graphics on South Carolina evacuation site connect many layers of data. (Image courtesy of Intergraph Geospatial Solutions)

"It just takes seconds now to get the data," says Donald McElveen, SCDOT’s manager of geographic information systems and mapping. He says the tool lets officials compare evacuation traffic to normal, watch for slow-downs and decide if alternative routes should be opened or lane directions reversed to relieve congestion.

The system was built by Intergraph Geospatial Solutions, Huntsville, Ala. It replaces an earlier one also built by Intergraph, in 1999. Both use data from sensors buried in lanes around the state.

Previously, data was accessed in spreadsheets by regions of the state. It had to be downloaded, merged and analyzed as precious time ticked off the clock. The new system uses a Web interface to almost instantly deliver information, sort it and assemble it into highly nuanced reports, charts and maps, including weather overlays.

The improvements came on line in June. They were road tested through Hurricane Charley and Tropical Storm Gaston last month. "It did very well," says McElveen.

Sensors automatically report lane-by-lane traffic volume and speed for hundreds of locations hourly. Software compares readings to past records at those places to track capacity. Anomalies, such as lanes with dropping speed or volume, can be called out through sorts.

Much of the system’s power and ease of use is in the speed and flexibility with which it delivers information. Through a rising-star format called Scalable Vector Graphics, highly compressed images of charts and maps are downloaded with embedded detail that is revealed by zooming in, or passing over triggers with a curser. Unlike other image formats, svg image resolution is scalable and doesn’t degrade with enlargement. Layers can be turned on and off. The only software needed is a small plug-in from Adobe, available for free over the Internet.

The state-wide evacuation route map, for instance, can be zoomed again and again, with no additional downloads, to reveal nodes of detail, such as individual Automatic Traffic Reporting Stations and cameras. Clicking on an ATR generates a report of its current and historic data. Clicking on a camera brings its live view. ATRs can also be accessed by clicking on buttons and drop down menus.

"It gives you an idea of what you can do with the Web now in terms of svg graphics," says McElveen. "This was a major update compared to what we had."