Relationships between truck accidents and selected geometric characteristics of interchanges are examined. Datasets containing information on truck accident at interchanges, traffic exposure and selected geometric characteristics are analyzed with an emphasis on interchange and ramp configurations. Most of the data in the report was obtained from the Washington State DOT, with limited data obtained from Colorado and California. In order to assess the impact of merging and diverging maneuvers on safety, the limits of ramp influence zones expressed in terms of accident frequencies were defined on the main line alignments. In addition, a procedure for identifying high-risk locations from the standpoint of truck operations was proposed. Freeway truck accidents were grouped by ramp type, accident type, and by four conflict areas of each merge or diverge ramp and compared on the basis of truck accidents per location and per truck mile of travel. Truck accident frequencies and rate ere not found to be significantly different by ramp type alone, but were significantly different by conflict area and accident type, both between and within ramp types. Truck accident frequencies at ramps were found to be less than proportional to truck volumes, meaning that high volume ramps had lower rates of truck accidents per truck mile of travel. Thus, a ramp's safety risk is related to accident type and conflict area, but not directly to truck volumes, which affects identifications of high-risk locations. Selected aspects of the AASHTO Policy on Geometric Design were examined from the standpoint of truck operations. This portion of the report was largely conducted as a literature review. In order to develop greater understanding of the relationship between truck accidents and geometrics of interchanges, the study conducted a series of truck driver surveys.


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    Title :

    Effects of Geometric Characteristics of Interchanges on Truck Safety


    Contributors:
    B. Janson (author) / J. Kononov (author) / W. Awad (author) / J. Robles (author) / B. Pinkerton (author)

    Publication date :

    1999


    Size :

    148 pages


    Type of media :

    Report


    Type of material :

    No indication


    Language :

    English




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