What If Another Floyd? - Escaping a Hurricane’s Wrath

The State of South Carolina is very vulnerable to the attack of hurricanes since it is adjacent with the Atlantic Ocean. In 1999 hurricane Floyd led most people living in the coastal region into a great panic. Take the city of Charleston as an example, 500,000 people rushed to Columbia, a safety heaven more than 200 kilometers away, through Interstate I-26. Since I-26 is the principal route going inland from Charleston to Columbia, there happened a standstill on the I-26. What is normally an easy two-hour drive took up to 18 hours to complete. Many cars simply ran out of gas along the way. Fortunately, Floyd turned north and spared the state this time, but the public outcry is forcing state officials to find ways to avoid a repeat of this traffic nightmare. The principal proposal put forth to deal with this problem is the reversal of traffic on I-26, so that both sides, including the coastal-bound lanes, have traffic headed inland from Charleston to Columbia. We have set up a mathematical model to analyze this problem. Our conclusion is that the performance of the evacuation plan would be greatly improved. According to our estimation, it will take more than 40 hours for 500,000 people if the traffic on the coast bound lanes are not reversed. But after the lanes are reversed, only about 24 hours will be enough for 500,000 people, which is a great improvement. So we suggest that under very urgent situations all lanes of traffic should be forced to extend inland. With more exact calculations we suggest that if more highways of small scales extending inland are available, we not hesitate to open them and utilize all its inland bound lanes. If people from more than one place wait for being evacuated, then another method should be presented. We may consider an alternative strategy, which staggers the evacuation, e.g. city by city, to further improve the evacuation plan’s performance. Under certain conditions we notice hat if all the people evacuate simultaneously it will lead to a disastrous result but that if they evacuate in turn they can avoid this. This phenomenon urged us to study what lies behind it. After extensive analysis we found out that it has something to do with the different time at which the hurricane will arrive in different places. A model is then set up and a recursive algorithm is proposed. This algorithm can help the decision maker to decide under what conditions a staggered strategy is called upon and what is the turn for evacuation of those cities.