Improved DTTE Method for Route-Level Travel Time Estimation on Freeways

Abstract

Travel time estimation plays an important role in advanced traveler information systems (ATIS) for dynamic traffic management. Static travel time estimation (STTE) and dynamic travel time estimation (DTTE) are two of the major methods widely explored for travel time measurement. To analyze their performance on route-level travel time estimation on freeways where congestion may occur, this study developed a framework consisting of four steps: traffic state prediction, travel time estimation, results evaluation, and performance comparison. A METANET-based macroscopic traffic model was developed and employed to predict traffic states based on loop detector data. Then, a novel DTTE method was developed and is proposed herein that combines the piece-wise linear speed-based (PLSB) method and the trajectory assumption algorithm. The indices of the mean absolute relative error (MARE) and the root mean squared error (RMSE) were employed to analyze estimation accuracy by the traditional STTE method and the proposed DTTE method. The comparison results illustrate that during high-demand periods, the proposed DTTE method outperforms the traditional STTE method by producing results that better match reference travel times, which were obtained from video sensors installed along the urban freeway corridor.