Travel time estimation method for urban road based on traffic stream directions

摘要

Traffic flow on a given link in an urban road network can be divided into several traffic streams, depending on their turning manoeuvres when entering and leaving the link. These traffic streams may experience various travel times due to multiple reasons, such as fluctuations in traffic demand/supply and stochastic arrivals/departures at signalised intersections. However, the current travel time estimation methods take traffic flow as a whole and produce a single estimation value. This approach can produce large errors. Furthermore, given the travel time information of each traffic stream, the results of dynamic traffic assignment models can be made much more accurate and the effect of signal controls improved. In this paper, a comparison analysis is conducted to verify the significant difference in link travel times of different traffic streams. Then, link travel time is redefined in consideration of traffic stream directions. This process is also successful in filtering noise, as shown in the numerical experiments. In addition, existing estimation methods cannot reflect real values or fluctuations of travel times in sampling intervals without any valid observational data. To solve this problem, a regression model is built and integrated into the travel time estimation model. Error analysis of several links on two different days demonstrates the improvements made by the model.