Effect of Rainfall on Travel Time and Accuracy of Travel Time Prediction with Rainfall

This study investigates travel time on an urban expressway in relation to rainfall intensities and proposes a travel time prediction model considering rainfall intensity. Past researches have developed travel time prediction models without considering accidents and rain. Normally accidents and rain increase travel time. Therefore, it is of interest to consider effects of rain and accident for travel time prediction. All data involved were collected from the Japan Meteorological Agency (JMA) and Tokyo Metropolitan Expressway; accident data traffic detected data and weather data were considered for the analysis. Travel time along vehicle trajectory method (Time-Slice Method) were used to find travel time; travel time profiles were drawn according to the strength of the rainfall and day of the week, and statistic tests were conducted to show difference between travel time profiles. This research found that travel time increases with rainfall intensity even in light rain conditions especially in daytime. Another objective of this research was to find the applicability of Travel Time Prediction Model considering rain. From this study, it was found that accuracy of travel time prediction decreases on rainy days compare to sunny days.