South Carolina’s Atlantic coastline of 187 miles is home to approximately 1.1 million people and sustains an additional 450,000 visitors per week during peak hurricane season. Most, if not all, rely on the state’s roadway system to bring them to the coast and also to evacuate them should it be necessary.
With the exception of two major east-west routes built in the past 40 years, the number of roads available for evacuation has not changed in almost 100 years. This limited number of roads presents evacuation managers with a challenging task when they must quickly move residents and visitors out of the path of an approaching hurricane.
The public expects state and local agencies to handle the evacuation management task with skill and success. Anything else is unacceptable and could result in lives lost and the public’s reluctance to participate in future critical evacuations. For an evacuation to be successful, officials know that two major benchmarks must be met. First, acceptable evacuation travel times must be established. Second, acceptable vehicular speeds must be maintained throughout the evacuation in order to meet these acceptable evacuation travel times.
South Carolina’s coast is divided into three evacuation zones. Evacuation routes for each zone were established years ago. However, in the late 1990s evacuation managers realized that major traffic management improvements were necessary.
A common problem was found in each of the three zones. A number of the older evacuation routes intersected each other. As a result, traffic on one route would have to stop and wait for traffic on the intersecting roadway until directed by law enforcement to proceed. This greatly impaired the efficiency of the individual routes.
To make matters worse, no formal plans existed to reverse the eastbound lanes of some multilane routes for westbound evacuation traffic. Such reversals can greatly increase capacity during an evacuation.
Finally, motorists all along the coast were left to their own wishes with regard to which route they would use when instructed to evacuate. This resulted in some routes being over capacity and others being severely underutilized.
To address these concerns, the South Carolina Emergency Management Division (SCEMD), which coordinates all emergency management functions statewide, requested that the South Carolina Department of Transportation (SCDOT) and the South Carolina Highway Patrol (SCHP) work cooperatively to improve the routing and management of hurricane evacuation traffic along the state’s coast. This was a logical approach in addressing the problem and has produced a much improved operational plan.
A new approach
A route evaluation team consisting of an SCDOT traffic engineer and an SCHP captain inventoried all routes leaving the coast in 2000 to determine the most direct paths away from the storm’s danger. The evaluation team was especially interested in isolating routes that paralleled each other and did not intersect. This new approach to selecting evacuation routes eventually resulted in significant changes to the old routing system.
Additionally, the team examined all new routes to ensure that they could carry motorists at least 100 miles from the coast. The older routes often failed to meet this requirement.
At the same time, the route evaluation team paid special attention to traffic operational issues and determined points where law enforcement presence would be needed. They also established locations for evacuation trailblazing signing.
Throughout the study, the route evaluation team met with county and municipal officials and law enforcement to obtain their input on the new routes. These meetings were essential to the project’s success, since local law enforcement is heavily involved in manning numerous traffic-control points along evacuation routes.
As the entire coastal evacuation route identification process was occurring, a parallel effort was under way to assign specific routes to the three coastal areas. These route assignments provide specific geographic areas with predetermined paths away from the coast. Evacuees now have specific route instructions on how best to depart from their home or vacation location and head inland. No longer is an evacuee’s route selection left to chance. These route assignments are designed to ensure that all evacuation-route roadway capacity is utilized to the fullest—an essential traffic management ingredient for successful evacuations.
Coincidental with the establishment of the new coastal evacuation routes was the birth of the SCDOT’s intelligent transportation system (ITS). The development of ITS began somewhat differently in South Carolina than in most states. Funding for ITS on selected routes in South Carolina was almost nonexistent and had to come from the SCDOT’s existing budget or from new highway construction project funds. The DOT also did not have the funds to construct a state-of-the-art traffic management center (TMC). With all of this in mind, the SCDOT began using a rather unique approach.
A view to an ITS
The SCDOT was extremely interested in applying ITS devices to monitor roads that were evacuation routes, but wanted to do it in a manner that also would allow the agency to use the technology to serve everyday traffic management needs. They began by placing video cameras and portable changeable message signs (CMS) at critical locations based upon evacuation and coastal traffic needs. This plan worked well, as in every case these locations had high tourist traffic and were prime evacuation monitoring points.
They carved out a 25-ft x 25-ft room in the basement of the SCDOT headquarters building in Columbia to serve as the state TMC. Working within a tight budget, much of the work was done in-house by Traffic Engineering and Information Technology Services staff. For example, the video wall was built by employees. They still operate out of this center today with hopes of a replacement in the near future. The center’s hours of operation were weekdays in the beginning, but today are 24/7. The point is this: They put their funds into ITS devices on the street rather than into a new TMC.
In the northern coastal area, which includes the famous Myrtle Beach Grand Strand, there are 25 highway video cameras, eight portable CMS, six permanent overhead CMS and six highway advisory radios (HAR). The HAR is used to convey more detailed traffic messages than can be displayed on the CMS. All of the CMS and HAR have specific programmed messages that are used when an evacuation occurs. The messages can be altered when necessary. All video is transmitted to the SCDOT headquarters TMC through leased commercial communication networks.
The central coastal area, where Charleston is located, features 58 highway video cameras, 25 portable CMS, 13 permanent overhead CMS and 11 HAR. In this area, I-26 is a major evacuation route that can be reversed from Charleston to Columbia—a distance of 100 miles. The SCDOT took advantage of an I-26 widening project to install ITS devices along a portion of the interstate. ITS equipment also was installed during the construction of the new Ravenel Bridge over the Cooper River in Charleston. Not only are these ITS installations vital to evaluating evacuation traffic, but they provide critical around-the-clock information for the daily traffic management of these facilities.
In the southern coastal area, where Hilton Head and Beaufort are located, the SCDOT partnered with Beaufort County in the creation of an ITS. Beaufort County Emergency Management Division has been active in its efforts to employ ITS to manage everyday traffic and evacuation traffic. As a result, 34 highway video cameras, five portable CMS, one permanent CMS and five HAR have been installed. These devices are operated and maintained by Beaufort County, but video is fed to the SCDOT headquarters TMC for daily information and use during evacuations.
In each of the above areas, a local TMC exists that manages the day-to-day duties associated with ITS. However, during an evacuation, the state TMC at SCDOT headquarters can take control of all devices. The SCDOT also has 175 video cameras, 52 portable CMS, 26 permanent CMS and 12 HAR in the five remaining inland metropolitan areas of the state that are served by interstates that carry evacuation traffic. These devices can be controlled both by local TMCs and the state TMC.
Furthermore, the state has employed a rather unique satellite communication system to communicate with its portable and permanent CMS statewide. This system allows the SCDOT to replace the cell phone communications in the portable signs and supplement landline communication in the permanent signs. The result is much faster CMS activation. This system not only benefits evacuation efforts but speeds the display of AMBER Alert messages throughout the year.
Good SHEPherds
In addition to the above ITS equipment, the SCDOT operates its incident management teams, known as the State Highway Emergency Program (SHEP), in all coastal evacuation areas and on interstates in major urban areas statewide. There are a total of 68 SHEP responders. During everyday operations, SHEP assists emergency responders when incidents occur on major roadways and offers services to motorists with disabled vehicles. During a hurricane evacuation, these valuable units are stationed along evacuation routes to ensure these roadways remain free of traffic flow restrictions. To increase efficiency, SHEP units are equipped with radios that allow communications with the Highway Patrol.
The SCDOT uses permanent traffic count stations on evacuation routes to ascertain traffic volumes and speed of travel. To determine how well traffic is flowing, the SCDOT, SCHP and the SCEMD compare evacuation count information with “normal,” everyday traffic volumes and speeds. They also receive count data from Georgia and Florida regarding northbound motorists on I-95. This information assists South Carolina agencies in judging I-95 traffic volume capabilities through South Carolina when hurricanes strike to the south.
The SCEMD, SCDOT and the SCHP have vigorously embraced roadway lane reversals on major roads leading from each of the coastal areas. The obvious reason for lane reversals is to increase roadway capacity, thereby improving evacuation travel times. As noted in the discussion of the central coastal area, lane reversals were established early on for I-26 between Charleston and Columbia. Currently, the SCDOT, SCHP and local law enforcement are prepared to effect a total of six separate lane reversal plans away from South Carolina’s coast. The total distance of these lane reversals is 170 miles.
In South Carolina, the governor makes the decision to evacuate. He receives information from the SCEMD regarding traffic, the progress of the storm and coastal population demographics to assist him in making the decision. ITS plays a vital role in gathering the necessary information that is processed by the SCDOT and SCHP in the State Emergency Operations Center. The governor also receives input from each of the affected coastal counties to help him with his decision. Communication among all of those involved in the evacuation process is the key to a successful event.
All of the ITS information that is gathered by the SCDOT can be transmitted to the governor for his review. This information is vital to him as he makes his decision for an evacuation. The governor is very much aware of the SCDOT’s ITS capabilities and supports their efforts of refinement and expansion.
Each June, the SCDOT, SCEMD and the SCHP conduct a field exercise to test their evacuation readiness. Personnel and traffic-control equipment are deployed at locations along key reversal routes to check timing and correctness of method. Realistic problems are simulated, and both law enforcement and SCDOT crews must demonstrate how they would react to unexpected challenges that might occur during an actual hurricane evacuation.
ITS is an essential part of South Carolina’s hurricane evacuation plan. Everyone involved in hurricane evacuation management is grateful for the real-time added insight that ITS provides. Just as important, however, are the strong relationships that are built among transportation engineers, law enforcement officers, emergency management officials and local governments as they put into place their evacuation plans. These two elements combined with constant preparation characterize South Carolina’s evacuation readiness for a hurricane that is certain to come.
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