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Real-Time GIS Assists South Carolina in Managing
Hurricane Floyd Evacuation
Article provided by Intergraph Corporation
Accessing the System
On Monday, Sept. 13, SCDOT personnel began preparing the Hurricane Evacuation Decision
Management System for utilization during Hurricane Floyd. At the time, the storm had
received
Category 4 status and was expected to hit Florida and South Carolina. With input from
SCDOT, Intergraph had programmed the system to generate three charts from the traffic
count data:
- comparison of traffic volumes over the previous five hours,
- comparison of traffic over the previous four days, and
- comparison of volumes for the current day, day before, and week before.
SCDOT personnel were also able to customize the charts to isolate traffic on specific
routes, such as Interstate 26 (1-26) heading west across the state, or on particular
metropolitan areas, such as Charleston, where many evacuation routes emerge toward
inland destinations. Charts were presented in bar and line graph formats.
"The traffic information lets the Governor know whether people are leaving in response
to an evacuation order, as well as how many are leaving," said McElveen. "If he issues
a mandatory or voluntary evacuation, the Governor must get a feel for how people are
responding in case he should have to change his tactics."
In addition to SCDOT headquarters, the password-protected system was accessed via the
Internet at two command posts in Columbia -- one at the Governor's office and the other
established by the state Emergency Preparedness Division. Both systems were staffed by
SCDOT personnel.
"Our job was to give the Emergency Preparedness Division and the Governor's office the
information they needed to make decisions," said Mark Hunter, an Assistant State
Maintenance Engineer in SCDOT's Highway Maintenance Office. "The challenge is to give
it to them in the simplest terms."
GeoMedia Web Map accomplished that because the Emergency Preparedness Division depended
on Hunter for updates on traffic counts on the major evacuation routes after the
Governor issued a mandatory evacuation order to low-lying areas at noon on Tuesday,
Sept. 14. At the peak volume late that evening, 80,000 vehicles left Charleston in one
hour. Hunter said the Emergency Preparedness Division staff was extremely interested in
the newly available traffic count information along with the other data. He printed out
numerous maps throughout Tuesday and Wednesday to track the movement of people.
"The colonel of the state highway patrol was in the Governor's Command Center," said
Kelvin Washington, an SCDOT Assistant Pavement Management Engineer who staffed the
system at that location. "We kept track of every spot that was having slowdowns. We
could get somebody on the ground, find out what the situation was, then get it cleared
up as fast as possible so traffic could continue."
By late afternoon on Tuesday, the system clearly showed what had most been feared --
traffic had come to a virtual stop on 1-26 outside Charleston because of volume
congestion. This information contributed to the decision to clear eastbound 1-26 of all
traffic and then re-open it to westbound traffic so that twice as many lanes could carry
vehicles away from that part of the coast.
The detour map proved valuable as well. It alerted authorities to the fact that some
bridges across the Cooper River above North Charleston had been closed on Sept. 14 in
anticipation of high winds. The alternate route was outlined in red. SCDOT added a
note stating that the alternate route may be closed by 8 p.m. that night if high winds
persisted. In addition, the real-time weather information would have been relied upon
heavily during the storm had it not veered northward. Even though the hurricane passed
by South Carolina, the system remained effective in the next few days.
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