This research report is intended to examine the geometric standards, guidelines, and practices used nationally and by other states to develop recommendations on roundabout design guidance for California. This research serves as a guidance tool in support of Caltrans policy and standards within the Highway Design Manual and other statewide documents. Recommendations made from this research will guide Caltrans and other agencies in California in designing and operating roundabouts. Several major areas were examined through this project, including assessing the operational performance of California roundabouts and developing calibrated capacity models consistent with recent national research (NCHRP 3-65); developing a calibrated intersection sight distance model; examining pedestrian and bicycle behavior at existing California roundabouts and comparing their performance to national observations; and developing a range of recommendations on geometric design parameters, including vehicle speeds, design vehicle, inscribed circle diameter, and issues related to roundabouts with more than four legs, roundabouts at freeway interchange terminals, and roundabouts in high-speed environments. The research resulted in a number of recommendations regarding the fundamental principles behind these elements, illustrated by tables and figures.


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    Title :

    Roundabout Geometric Design Guidance


    Contributors:
    Z. Z. Tian (author) / F. Xu (author) / L. A. Rodegerdts (author) / W. E. Scarbrough (author) / B. L. Ray (author)

    Publication date :

    2007


    Size :

    113 pages


    Type of media :

    Report


    Type of material :

    No indication


    Language :

    English




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