Assessment of I-4 Contraflow Plans

Better use of the available road network is critical to improving the evacuation operation during a disaster. Contraflow operations help increase the capacity of the available network by reversing the direction of inbound lanes to outbound lanes. This helps improve the outflow from a region threatened by disaster. One of the major issues associated with contraflow operations is determining the locations for access to the contraflow lanes from the normal-flow lanes. These accesses are also referred to as crossovers. Four different strategies with different crossover locations were tested on the I-4 evacuation route from Tampa to Orlando, Florida. It was found that the provision of two crossovers, one after Tampa and another after Plant City, performed the best but was only marginally better than the provision of one crossover after Tampa. Therefore, considering the cost and personnel needed to provide a crossover, the provision of one crossover after Tampa was found to be a more logical choice than the provision of two crossovers. It was observed that the time required to run the microscopic simulation to arrive at the results was extremely long. To overcome this drawback, the cell transmission model (CTM) was calibrated and run for the same four strategies. It was observed that the results were extremely close to the results from the microscopic simulation. The robustness and speed of CTM make it ideal for use as part of a decision support system to help determine the best strategies in real time. This will help emergency management officials make real-time decisions in the event of unforeseen drops in capacities because of incidents or vehicle breakdowns.