Variability of travel time estimates using probe vehicle data

Accurate link travel time estimations obtained using probe vehicles are crucial to reliable dynamic route guidance systems. This study attempts to understand what level of travel time estimation reliability can be achieved from a given frequency of probe data. Hence the focus is on the variability of link/roadway segment travel time estimates for different data frequencies. Data is simulated to compare the variability of probe information; lower frequency probe samples are simulated by selectively deleting parts of higher frequency samples. The results suggest that higher frequency probe data do not always yield less variance in link travel time estimates, while lower frequency data have a smaller variance at links just before signalized intersections. On the other hand, the accuracy of roadway segment travel time estimates using low-frequency probe data appear little different from high-frequency data. Consequently, there is potential for the wide use of low-frequency data in route guidance applications