Highlights Distinguishes vehicle-to-vehicle vs. day-to-day variability of travel time. Applicable at network level. Can help assess and evaluate impact of different intervention scenarios on reliability. Model derived mathematically and calibrated with actual and simulated data. Robust relation extends network traffic theories to address reliability.

    Abstract This paper proposes a compound probability distribution approach for capturing both vehicle-to-vehicle and day-to-day variability in modeling travel time reliability in a network. Starting from the observation that standard deviation and mean of distance-normalized travel time in a network are highly positively correlated and their relationship is well characterized by a linear function, this study assumes multiplicative error structures to describe data with such characteristics and derives a compound distribution to model travel delay per unit distance as a surrogate for travel time. The proposed Gamma–Gamma model arises when (within-day) vehicle-to-vehicle travel delay per unit distance is distributed according to a Gamma distribution, with mean that itself fluctuates from day to day following another Gamma distribution. The study calibrates the model parameters and validates the underlying assumptions using both simulated and actual vehicle trajectory data. The Gamma–Gamma distribution shows good fits to travel delay observations when compared to the (simple) Gamma and Lognormal distributions. The main advantage of the Gamma–Gamma model is its ability to recognize different variability dimensions reflected in travel time data and clear physical meanings of its parameters in connection with vehicle-to-vehicle and day-to-day variability. Based on the linearity assumption for the relationship between mean and standard deviation, two shape parameters of the Gamma–Gamma model are linked to the coefficient of variation of travel delay in vehicle-to-vehicle and day-to-day distributions, respectively, and can be directly estimated from the slope of the associated mean-standard deviation plots. An extension of the basic model form was also introduced to address potential deviations from this linearity assumption. The extended Gamma–Gamma model can account for time-of-day variations in mean-standard deviation relationships—such as hysteresis patterns observed in mean and day-to-day variation in travel time—and incorporate such dynamics in travel time distribution modeling. In summary, the model provides a systematic way of quantifying, comparing, and assessing different types of variability, which is important in understanding travel time characteristics and evaluating various transportation measures that affect reliability.


    Zugriff

    Zugriff prüfen

    Verfügbarkeit in meiner Bibliothek prüfen

    Bestellung bei Subito €


    Exportieren, teilen und zitieren



    Titel :

    Compound Gamma representation for modeling travel time variability in a traffic network


    Beteiligte:
    Kim, Jiwon (Autor:in) / Mahmassani, Hani S. (Autor:in)


    Erscheinungsdatum :

    2015-06-22


    Format / Umfang :

    24 pages




    Medientyp :

    Aufsatz (Zeitschrift)


    Format :

    Elektronische Ressource


    Sprache :

    Englisch





    Characterizing Travel Time Variability in Vehicular Traffic Networks

    Mahmassani, Hani S. / Hou, Tian / Dong, Jing | Transportation Research Record | 2012


    Mapping of bus travel time to traffic stream travel time using econometric modeling

    Banik, Sharmili / Vanajakshi, Lelitha / Bullock, Darcy M. | Taylor & Francis Verlag | 2022


    Impact of Traffic Flow on Travel Time Variability of Freeway Corridors

    Tu, Huizhao / Van Lint, J. W. C. / Van Zuylen, H. J. | Transportation Research Record | 2007


    Forecasting travel time variability

    Eliasson, J. / Association for European Transport | British Library Conference Proceedings | 2006