At signalized intersections, turning vehicles often use the same share lane together with the through traffic. For example, at small and medium intersections, there is often only a single lane approach which is used both by left-turn and through movement. Obviously, in case of those single-share lanes, only a permitted control for the left-turn movement is applicable. Since a permitted left-turn movement has to give way to the opposing through movement, it has to wait if necessary and thus impedes the through movement in the same direction. In the reality, if the left-turn movement is permitted controlled, the through movement at the same approach can be totally blockaded by waiting turning vehicles during the green time. Thus, the green time for the share lane cannot be efficiently utilised and the lane capacity under consideration cannot be fully received. In the existing capacity manuals for traffic quality assessment, there are not yet adequate procedures for taking into account that effect of blockage. In the current US Highway Capacity Manuel there are only empirical regression functions for the effect of blockage based on measurements and simulation studies. Unfortunately, using this regression functions, some important margin conditions are not satisfied. As a result, the capacity of the share lane is calculated inaccurately under particular conditions. In this paper, a mathematical model is presented for an exact calculation of the blockage probability caused by permitted turning vehicles and for the estimation of the capacity of single-share lanes at signalized intersections. According to the probability and combinatory theory, a mathematically exact model is developed. The proposed model can be applied to share lanes either with left-turn or with right-turn movement. Respectively, by extending the model, also the capacity for the Right-Turn-On-Right situation can be exactly calculated. In contrast to the regression functions in the US Highway Capacity Manuel, the proposed new model satisfies all necessary boundary conditions. The results of the model fill out a gap in the current procedures of capacity estimations at signalized intersections. The proposed model has the capability to be incorporated into the exiting highway capacity manuals and other regulations. The model in this paper is developed for fixed time controlled and isolated intersections. In the future, an extension to actuated, adapted or coordinated intersections is expected.


    Access

    Check access

    Check availability in my library

    Order at Subito €


    Export, share and cite



    Title :

    Determining Capacity of Share Lanes with Permitted Left-Turn Movements at Signalized Intersections — Modeling the Effect of Blockage


    Contributors:
    Wu, Ning (author)

    Conference:

    Sixth International Conference of Traffic and Transportation Studies Congress (ICTTS) ; 2008 ; Nanning, China



    Publication date :

    2008-07-17




    Type of media :

    Conference paper


    Type of material :

    Electronic Resource


    Language :

    English




    Capacity Modeling of Permitted Left-Turn Signalized Intersections with Probabilistic Priority

    Wang, Daobin / Yang, Guangchuan / Tian, Zong et al. | Transportation Research Record | 2020




    Lengths of Left-Turn Lanes at Signalized Intersections

    Kikuchi, Shinya | Online Contents | 1993


    Determining Lengths of Left-Turn Lanes at Signalized Intersections under Different Left-Turn Signal Schemes

    Kikuchi, Shinya / Kronprasert, Nopadon | Transportation Research Record | 2010