April 16, 2002 By Dan Page
On Sept. 22, 1989, Hurricane Hugo hit the coast of South Carolina and left a path of death and destruction that penetrated deep inland. That triggered a series of events that led to an operational decision support system by 1999. In that year, Hurricane Dennis provided a dress rehearsal, allowing the state to test features of the system before the hurricane finally skirted the South Carolina coast and skipped away without incident. It was three weeks later, when Hurricane Floyd began to churn the waters of the Mid-Atlantic, that the real test came.
With winds building to a Category 5 storm, Floyd rolled ominously toward the southeastern coastline and South Carolina state officials launched what has been called the largest peacetime evacuation in U.S. history. From Beaufort to Myrtle Beach, more than 700,000 people streamed onto the highways to escape inland. As emergency personnel along the 150-mile coastline began the evacuation for what might have been the worst natural disaster in the state's history, they worked with up-to-the minute detailed information provided by South Carolina's Department of Transportation (DOT).
In the end, Floyd fell flat, blowing itself out at sea and making an innocuous landfall. But the system worked. Those who had to leave the coastal areas got out in time. Of equal importance, the data made available by the experience provided a solid basis for evaluation and refinements that would make the next evacuation go even more smoothly.
Integrating Existing Data Sets
"The system basically integrates and displays up-to-date weather data with real-time traffic data taken from sophisticated induction strips that are built into the pavement," said Rob Mott, senior technical manager with Intergraph, which assisted the state in developing the GIS components of the evacuation system. "These air-pressure tubes record traffic counts and are in place at more than 150 locations. This system was already in place, so it was ideal for collecting data in connection with the hurricane evacuation system."
According to Mott, the evacuation support system makes traffic counts available via the Web to the operators at the DOT. Using historical information about traffic flow and road capacity, these operators can assess how an evacuation is proceeding. They can also determine how much time is left before the storm makes landfall and locate the most critical areas of potential threat. Using this information, other state officials can implement a variety of strategies designed to minimize traffic jams and speed the evacuation process.
For example, traffic can be rerouted to avoid tie-ups or bad road conditions. Additionally, traffic lanes can be reversed, so lanes that would normally be used to go toward the coast can be opened up to double traffic capacity away from the coast.
The real time weather data is presented in pictorial form. It is not dynamic, but rather a snapshot that shows coastlines, highways and terrain features. Because hurricanes come in with a very distinct cloud formation, it is easy to see where the front is, and that pictorial information is useful in giving perspective to the traffic data.
Simplified Information Distribution
To combine and distribute digital information over the Web, South Carolina's DOT is using GeoMedia Web Map, a Windows-based software suite that accepts and publishes multiple data sources over a network. Maps can be displayed and