Graduate Thesis Or Dissertation


A safety evaluation of turn lane-adjacent bike lane configurations in Portland, Oregon Public Deposited

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  • The Manual on Uniform Traffic Control Devices prohibits positioning a bike lane right-adjacent to a vehicle turn-only lane to mitigate the potential for right-hook crashes. However, it provides no specific guidance on positioning with respect to bus-only lanes. This thesis describes a before/after safety evaluation of bike lanes positioned left and right-adjacent to vehicle turn-only lanes with and without shared bus-only lanes. Three hundred total hours of video data was collected across five intersections and three time periods—one “before construction” and two “after construction” periods—in Portland, Oregon. Observers applied the American Traffic Conflicts Technique to extract conflict frequency and type from the video data to compare across and within locations for each time period. Results suggest that locations with a bike lane positioned right-adjacent to a vehicle turn-only lane, regardless of whether it was a shared bus-only lane, experienced predominately right-hook conflicts between bicyclists and vehicles on the major approach. Locations with a bike lane positioned left-adjacent to a turn-only lane, regardless of whether it was a shared bus-only lane, experienced a combination of conflict types, including right-hook and merging related conflicts. Crash frequency did not appear to significantly vary based on whether the bike lane was positioned right- or left-adjacent, nor based on whether the turn lane was a shared bus-only lane.
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  • This work was funded by the Portland Bureau of Transportation (PBOT).
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