Transformation between Uninterrupted and Interrupted Speeds for Urban Road Applications

Abstract

Unlike the freeway traffic stream, the urban traffic stream is generally interrupted by signals, and the traffic data observed may differ from the true (uninterrupted) flow characteristics. This paper deals with the transformation between interrupted and uninterrupted speeds on an urban road with signalized intersections. The conventional shock wave model and two modified versions of the shock wave boundary that address unrealistic characteristics of the conventional shock wave model are developed. A method of integrating probe and detector data for speed transformation is also discussed. The proposed methods are tested with a virtual isolated signalized intersection by varying the approach demand. The numerical results suggest that all models can significantly reduce the difference between the actual and the estimated uninterrupted (or interrupted) speeds compared with the case of doing nothing. The applications of the proposed methods, including the development of a flow–speed model and link travel time estimation, are also given.

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