Highlights Identify deficiencies of single-regime models for congested states. Weighted least square method addressing biased selection bias. Single-regime models for both free-flow and congested states. Theoretical investigation and extensive applications.

    Abstract The speed-density or flow-density relationship has been considered as the foundation of traffic flow theory. Existing single-regime models calibrated by the least square method (LSM) could not fit the empirical data consistently well both in light-traffic/free-flow conditions and congested/jam conditions. In this paper, first, we point out that the inaccuracy of single-regime models is not caused solely by their functional forms, but also by the sample selection bias. Second, we apply a weighted least square method (WLSM) that addresses the sample selection bias problem. The calibration results for six well-known single-regime models using the WLSM fit the empirical data reasonably well both in light-traffic/free-flow conditions and congested/jam conditions. Third, we conduct a theoretical investigation that reveals the deficiency associated with the LSM is because the expected value of speed (or a function of it) is nonlinear with regard to the density (or a function of it).


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    Title :

    On the fundamental diagram for freeway traffic: A novel calibration approach for single-regime models


    Contributors:
    Qu, Xiaobo (author) / Wang, Shuaian (author) / Zhang, Jin (author)


    Publication date :

    2015-01-08


    Size :

    12 pages




    Type of media :

    Article (Journal)


    Type of material :

    Electronic Resource


    Language :

    English







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