The sight distance (SD) on a three-dimensional (3-d) compound curve has been studied recently in the absence of obstacles at road sides. Often, physical barriers are installed at road sides or in a roadway median for reducing potential collision severities; these rigid, semi-rigid, or even temporary cushion-type barriers can limit or reduce the driver's sight distance, depending on their horizontal offset distances away from the nearest edge of traveled way (ETW). The closer a barrier to the ETW is, the shorter the driver's sight distance would be. Since most barriers are constructed to prevent running-off road or crossing-median collisions, it is crucial to check whether the installation would reduce the driver's sight distance and potentially cause other traffic collisions such as rear-end or side swipe collisions. In this paper, an exact analytic framework is formulated with derived equations the first time to calculate the sight distance on a 3-d compound curve in the presence of a median barrier, a roadside barrier, or a temporary cushion or barrier used for construction or other maintenance purposes. This framework provides an engineer a handy tool to examine the possible change of SD in the presence of a barrier and choose the required horizontal offset/clearance of a barrier from the nearest traveled way edge to meet certain design criteria or standards. This critical offset distance determined using this framework not only reinforces the importance of having roadside clearance recovery zones on highways but also provides a method to determine its horizontal clearance from a different standpoint. This analytic framework can easily be programmed into an Excel spreadsheet to evaluate the design of a physical barrier and its potential influence on sight distance along a 3-d compound horizontal and vertical curve. Transportation engineers or practitioners may find this design tool handy and useful once the programmed spreadsheet is saved in a shared or a flash/thumb drive. Note that the sight distance on a two-dimensional curve, such as a horizontal or a vertical curve, can be calculated straightforward as special cases using the programmed spreadsheet.


    Zugriff

    Download


    Exportieren, teilen und zitieren



    Titel :

    Exact Sight Distance Determination on Compound Vertical and Horizontal Curves in the Presence of Road Barriers


    Beteiligte:


    Erscheinungsdatum :

    2013




    Medientyp :

    Aufsatz (Zeitschrift)


    Format :

    Elektronische Ressource


    Sprache :

    Unbekannt




    Stopping Sight Distance and Horizontal Sight Line Offsets at Horizontal Curves

    Wood, Jonathan S. / Donnell, Eric T. | Transportation Research Record | 2014


    Limited Sight Distance Warning for Vertical Curves

    M. Freedman / L. K. Staplin / L. E. Decina et al. | NTIS | 1984



    Consideration of Sight Distance in Placement of Concrete Barriers on Horizontal Curves of Roads

    Sarhan, Mohamed / Hassan, Yasser | Transportation Research Record | 2012


    Required Stopping Sight Distance on Crest Vertical Curves

    Taignidis, I. / Kanellaidis, G. | British Library Online Contents | 2001