Highway Evacuations in Selected Metropolitan Areas: Assessment of Impediments
Charleston, South Carolina
INRIX® National Traffic Scorecard 2009
South Carolina improved its evacuation plans after Hurricane Floyd moved through the southeast in 1999, triggering one of the largest evacuations and contraflow operations in U.S. history until Katrina devastated Louisiana. Since then, South Carolina and its at-risk jurisdictions have been reviewing, revising, exercising, integrating, and improving their evacuation plans annually in preparation for hurricane season. South Carolina officials stated that the Charleston evacuation plan is current and is incorporated into the State and local emergency management agency's Emergency Response and Evacuation Plans.
The South Carolina DOT established and continues to sustain strong partnerships with the Highway Patrol and local communities to maximize the plan's effectiveness and efficiency. Every other year South Carolina conducts a table top exercise of the plan. On the opposite years a full field test of the plan is conducted with deployment of personnel and equipment. Authorities use lessons learned and good practices to enhance the plan during its annual revision.
The existing plan covers jurisdictions along the entire coastline. It establishes Evacuation Zones designed to minimize "clearance time," which is defined as the time it takes to move the first person to the last person out of an affected or high-threat area. The zones cover:
- Zone One (North) - Myrtle Beach, Georgetown, North Myrtle Beach, Surfside Beach, Garden City, Pawley's Island, and Conway
- Zone Two (Central) - Charleston, Mt. Pleasant, Isle of Palms, Johns Island, James Island, Kiawah Island, Sea Brook Island, and Edisto Island
- Zone Three (South) - Hilton Head and Beaufort
Authorities designed the plan with the assumption that they must move the affected population 100 miles away from the coast.
Top Highway Impediments
Top Highway Impediments
- Infrastructure Constraint I-26
- East-West Evacuation Routes
- Lane Restrictions
- ITS Capabilities along Evacuation Routes
- Incident Responder Coverage Along I-26, Charleston to Columbia
The interviewees reported that the following impediments would impact a large-scale, mass evacuation from the Charleston area:
- Infrastructure Constraints - I-26 - Current capacity on 1-26 would be exceeded during a mass evacuation event.
- East-West Evacuation Routes - East-West evacuation out of Charleston, as well as other coastal areas to include the Hilton Head Island/Beaufort and Myrtle Beach areas, would be improved by additional routes and crossings.
- Lane Restrictions - Respondents stated that a significant deficiency exists along current evacuation routes where traffic lanes reduce from four to two travel lanes, e.g., US 521/SC 261 from Andrews S.C. to US 378.
- ITS Capabilities along Evacuation Routes - Expand the ability to share real-time information with Highway Patrol and Emergency Responders by adding surveillance cameras and Dynamic Message Signs (DMS) to routes.
- Incident Responder Coverage Along I-26, Charleston to Columbia - Safety/Service Patrols and Law Enforcement officers constitute important resources to clearing NHS roadway incidents on a daily basis. However, most are concentrated along roads within major metropolitan areas. Charleston believes that the limited coverage outside of the metro Charleston area would impact the flow of evacuation traffic along the I-26 corridor between Charleston and Columbia if such responders were not available and positioned along the corridor to address incidents during the evacuation.