8: Road Network Reliability Analysis Using Vehicle Routing and Scheduling Procedures

This paper proposes “Cost Reliability” as a new indicator being useful for assessing the service level of road network. A computer based procedure was developed for estimating the cost distribution and reliability of road network using the vehicle routing and scheduling problem with time windows, and then applied to a test road network with its link travel times being assumed to be normally distributed. Results showed that total cost of each company is not normally distributed due to designated time windows at customers and becomes larger as delay time unit penalty rate increases. This implies that the results from the cost reliability analysis might be different from those from conventional travel time reliability analysis. It is also found out through the road network reliability analyses that probabilistic vehicle routing and scheduling procedures are more robust and performs better than deterministic procedures.