United States Department of Transportation
i
Crash Modification Factor for Corner Radius, Right-Turn Speed, and Prediction of Pedestrian Crashes at Signalized Intersections
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2022-01-01
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[PDF-3.05 MB]
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Abstract:This project investigated the influence of intersection corner radius on pedestrian crashes and right-turn vehicle speed. The corner radius can be unique to each corner at an intersection; therefore, this study assigned crashes to an intersection corner rather than to the entire intersection. For corner-level pedestrian crashes, the following variables were found to be positively related: pedestrian volume on the approach leg, pedestrian volume on the receiving leg, vehicle volume on the approach leg, vehicle volume on the receiving leg, corner radius, and shoulder width. The number of pedestrian crashes was higher when both legs at a corner were one-way streets with traffic moving away from the corner or when there was a mix of two-way and one-way operations present at the intersection. Fewer pedestrian crashes occurred when on-street parking existed on the approach leg. The findings from the study support the development of a crash modification factor (CMF) for corner radius. Assuming a baseline condition of 10 ft, the pedestrian CMFs for corner radius for the range of corner radii included in the evaluation went from 1.00 for a 10-ft radius to 1.59 for a 70-ft radius. In the operational analysis, right-turn speeds were found to be a function of corner radius. Other variables that influenced right-turn speed included headway to the preceding vehicle, traffic signal indication (yellow versus green), turning vehicle type (car or truck), and preceding vehicle movement (straight or right). The final selected model from this study can be used to predict turning speeds at different percentile levels. For example, the model can predict 50th or 85th percentile speeds. The findings from this study can also be used to update the discussion contained in design manuals, especially with respect to designing intersections.
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