Roundabouts have become a vital part of the transportation infrastructure in the United States. It is critical that engineers consider all variables and accurately predict the performance of roundabouts prior to installation. Two common methods for assessing the performance of roundabouts are the Highway Capacity Manual (HCM) method in the U.S. and the Kimber equation in Europe. The objectives of this study were (1) to determine if geometric factors, such as inscribed diameter, influence roundabout capacity; and (2) to compare driver critical gap behavior in Southern Illinois to values from previous research. In this study, field observations measured vehicle critical gaps and capacity flow rates at roundabouts in Southern Illinois. The results found (1) correlations between roundabout diameter and entry capacity, which suggest an opportunity for future refinement of the HCM methods; and (2) that a critical gap estimate of 4.2 s is appropriate for Southern Illinois, which differs from default values from the HCM (5 s).


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    Title :

    Roundabout Operations in Southern Illinois


    Contributors:

    Conference:

    International Conference on Transportation and Development 2021 ; 2021 ; Virtual Conference



    Publication date :

    2021-06-04




    Type of media :

    Conference paper


    Type of material :

    Electronic Resource


    Language :

    English



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