Travel Time Prediction of Urban Expressway in Unstable Traffic Flow

Travel time is an important parameter in Intelligent Traffic System (ITS). The methods in existence mostly aim at stable flow, but are not applicable for unstable flow, so can't be used to provide reliable travel time for drivers in congested condition. This paper presents a technique based on macroscopic traffic flow model. The basic process is to divide the research section into several segments, use macroscopic flow model to estimate the future speed of these segments, calculate travel time of each segment and accumulate them; wherein, Papageorgiou model is adopted. Travel time is calculated by updating instant speed every 20 seconds and at the start and end of a segment, so that the calculated result is close to the real. The technique can provide reference for traffic guiding.