Dynamic Estimation of Travel Time Reliability for Road Network Using Trajectory Data

To evaluate the operation of an urban transportation system by accurately analyzing the reliability of a road network, with the aim of reducing the substantial fluctuation of travel time, a method for dynamically estimating the reliability of road network travel time is proposed. First, the definition of travel time reliability is given by referring to system reliability theory: the possibility that all travelers in the road network reach their destination within a predetermined time. The travel time reliability is numerically expressed as the probability that the ratio of delay to travel time (RODT) is less than a certain value. Then, actual data are used to prove that the RODT of vehicles in the road network obeys the normal distribution, based on which a data-driven method of travel time reliability estimation is proposed. The travel time reliability of a real-world network is estimated based on the trajectory. Finally, the variation in travel time reliability under different road network capacities is studied, and the accuracy of the estimated travel time reliability under different trajectory data penetration rates is analyzed. The dynamic estimation method of travel time reliability proposed in this paper supports better understanding of the operation efficiency of urban road traffic systems, to help better evaluate the performance of road network systems and provide a basis for road network reliability optimization.