Empirical Analysis of Travel Time Reliability Measures in Hanshin Expressway Network

Abstract

Travel time reliability is a key indicator of system performance and has become increasingly important in today's world as businesses as well as households require on-time transportation for their activities. In order to analyze travel time reliability, an enormous amount of traffic flow data is needed. Recently, the development of advanced traffic flow data collection systems has enabled us to handle that. This article aims to examine the fundamental characteristics of travel time reliability measures using the traffic flow data from the Hanshin Expressway network. Differences and similarities in characteristics (average travel time, 95th percentile travel time, standard deviation, coefficient of variation, buffer time, and buffer time index) are investigated on one radial route (Route 11: Ikeda Line). The result shows that buffer time and buffer time index profiles have a similar tendency as those of the standard deviation and coefficient of variation, respectively. Differences in characteristics among five radial routes in the network are also investigated in order to explore each route's characteristics of time-of-day variation of traffic flow. Additionally, the effect of traffic incidents on travel time reliability measures is analyzed on one radical route (Route 14: Matsubara Line). The results show that traffic incidents are the dominant factor for travel times in off-peak hours on the Hanshin Expressway network.