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  • Mobility and traffic research  (2)
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  • Mobility and traffic research  (2)
  • 1
    Online Resource
    Online Resource
    SAGE Publications ; 2023
    In:  Transportation Research Record: Journal of the Transportation Research Board Vol. 2677, No. 8 ( 2023-08), p. 509-524
    In: Transportation Research Record: Journal of the Transportation Research Board, SAGE Publications, Vol. 2677, No. 8 ( 2023-08), p. 509-524
    Abstract: Reliable real-time traffic state identification (TSI) provides key support for traffic management and control. Although substantial efforts have been devoted to TSI, considering the high dynamics and stochasticity of traffic flows, there remain challenges in providing reliable and consistent TSI results, especially in online network–level applications. In this study, we propose a time series clustering-based offline-online modeling framework for reliable TSI using high-resolution traffic data. Specifically, in the proposed framework, the offline module extracts representative traffic state patterns from massive historical data, which serve as the state references in the online module when performing real-time TSI with streaming information. Instead of point data, the proposed framework uses high-resolution traffic data in the form of time series, providing rich information on traffic flows and details on their short-term fluctuations and stable long-term trends. In the offline module, considering the fuzziness of traffic states, we introduce a fuzzy c-means based clustering method for offline traffic flow series clustering and traffic state pattern extraction, within which the dynamic time warping algorithm is adopted for measuring the similarity between different time series, and the optimal number of clusters is determined by a proposed critical segment–based method to reach consistent TSI in network-wide applications. In the online module, a dynamic programming–based real-time TSI approach is developed to produce reliable and smooth identification results. Extensive numerical experiments on a 20-mi-long freeway corridor in California, USA, were performed to validate the proposed framework. Results demonstrate the effectiveness of the proposed framework.
    Type of Medium: Online Resource
    ISSN: 0361-1981 , 2169-4052
    Language: English
    Publisher: SAGE Publications
    Publication Date: 2023
    detail.hit.zdb_id: 2403378-9
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  • 2
    Online Resource
    Online Resource
    SAGE Publications ; 1998
    In:  Transportation Research Record: Journal of the Transportation Research Board Vol. 1647, No. 1 ( 1998-01), p. 104-110
    In: Transportation Research Record: Journal of the Transportation Research Board, SAGE Publications, Vol. 1647, No. 1 ( 1998-01), p. 104-110
    Abstract: To improve the conventional lengthy and inefficient design process for bridge railings, which features repetitions of costly full-scale experiments, and to support the bridge railing design with analytical data, this research developed a three-dimensional (3-D) simulation model that can reconstruct a vehicle-bridge railing impact analytically and visually using MADYMO (MAthematical DYnamic MOdel), developed by TNO. Both the vehicle and the bridge railing are modeled as rigid multi-body systems. A nonlinear tire model and a 3-D suspension are introduced to increase the reality of the vehicle motion during impact. The bridge railing is divided into poles and longitudinal railings. The bending characteristics of the poles and the longitudinal railings are described by the properties of corresponding universal joints attached to them. The simulation model is verified by experimental data of three different conditions using heavy trucks (8 tons and 20 tons). The validation reveals that the 3-D model can reconstruct vehicle-bridge railing crashes with a high degree of accuracy with respect to the vehicle performance and the deformation of the bridge railing, which are the most important concerns in the designs of bridge railings. The validated crash model is then employed to determine the necessary stiffness of the bridge railing under different conditions. Curves describing the relationship between the stiffness of the poles and the longitudinal railings are calculated for various impact severity values. These curves provide analytical grounds for the stiffness designs of the bridge railings.
    Type of Medium: Online Resource
    ISSN: 0361-1981 , 2169-4052
    Language: English
    Publisher: SAGE Publications
    Publication Date: 1998
    detail.hit.zdb_id: 2403378-9
    Location Call Number Limitation Availability
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