Short-term forecasting of travel time and reliability

In this paper, a traffic flow simulator (TFS) is presented to forecast the short-term travel time and reliability that can be served as a predicted travel time database for the Hong Kong transport information system or advanced traveler information system. The forecasted travel time information is useful for the pre-trip planning of the drivers. The drivers can decide their departure time and mode choice based on the forecasted travel times and reliabilities. A case study has been carried out in the Hong Kong Island during the AM peak period. A stochastic deviation coefficient of link flow is incorporated in the TFS so as to simulate the minute-by-minute fluctuation of traffic flows within the peak hour period. The purposes of the case study are: 1) to show the applicability of the TFS for larger-scale road network; and 2) to illustrate the short-term forecasting of travel time and reliability in practice. The results of the case study show that the TFS can be applied for real network effectively. The TFS forecasted travel times and the observed travel times are compared. The findings show that the observed travel times fell in the 90% confidence intervals of the TFS forecasted travel times. To distribute the traffic information to the drivers, a TIS website is currently being developed in The Hong Kong Polytechnic University for displaying the traffic information in Hong Kong.