THE USE OF HISTORICAL DATA FOR TRAVEL TIME FORECASTING IN THE ADVANCED TRAVELER INFORMATION SYSTEM

For the last two years, Korean Highway Cooperation (KHC) has developed a location-based Dynamic Route Guidance System (DRGS). The targeted end users of the system are mobile-phone users in Korea. The service is scheduled to be commercialized in 2005. Spatially the system will cover all of the expressways which is about 2,800 km and some of the National highways which is about 500 km. The focus of this paper is about the use of historical travel time data for travel time forecasting which is embedded in the location-based DRGS development project of KHC. This study firstly shows that for certain future time periods (e.g. 60 minutes later from now on) travel time forecasting using only the historical profile without real-time profile is better than the one using real-time profile or both. Then the methods of constructing historical profile including removing outliers, identifying optimal amount of historical data for the historical profile, and determining optimal update frequency of the historical profile are discussed. Finally the proposed methods are demonstrated with the travel time information collected from Kyongbu expressway in Korea.