Analysis of freeway service patrol with discrete event-based simulation

As an efficient incident management program, freeway service patrol has gained wide popularity. There is increasing need for developing systematic procedures of planning the program to ensure efficient resource allocation and to achieve maximum benefits. A discrete event-based simulation model is developed to replicate the patrol process that includes districting, incident generation, response vehicle dispatching and routing, and incident clearance. Model validation proves its capability to accurately replicate the incident generation/distribution process. Later, the Interstate-95 freeway in south Florida is used as a model application example to test alternatives, and the improved alternative shows better performance compared with the previous even-length districting method and the currently used even-activity districting approach. Besides traditional roving scheme, the simulation model also has the capability to evaluate the prepositioning schemes. Furthermore, sensitivity analysis is performed to examine the impact of operational parameter settings, such as beat districting, incident detection rate, and incident frequency. Although continuous efforts are needed to develop a more comprehensive simulation model for the freeway service patrol program, the application example presented in this study reveals promising application results, and provides an insight into the patrol process as well as a better understanding of the impact of parameters on performance.