Time Granularity Selection for Expressway OD Realtime Prediction

Abstract:

Two methods, yearonyear prediction method and circularityratio prediction method, are often resorted to in the realtime origindestination(OD) prediction. The former depends on historical information, such as the data about the previous day or week. The latter depends on the data of adjacent period to predict the realtime OD. The size of time granularity, the time period used in the realtime prediction of expressway network has a significant effect on the stability and accuracy of OD prediction results. The Augmented Dickeyfuller Test(ADF) unit root test and Kmeans algorithm are employed to study the effect of prediction results, and the size of time granularity is recommended. Compared with circularityratio prediction method, yearonyear prediction method can lead to the more stable and accurate result and a more satisfied time granularity is between 30 minutes and one hour.

Key words:time granularity; expressway origindestination(OD) prediction; volatility; similarity