Evaluation of Posted Speed Limits Reductions on Urban Roads with a High Percentage of Cyclists

This paper presents a before and after analysis of the impact posted speed limit (PSL) changes on passenger car (FHWA class 2 vehicle) speeds in Portland, Oregon. The study focuses urban roads, comparing sites that underwent PSL 5-mph reduction (treatment sites) where did not change (control sites). Sites with high percentage priority for cyclists (neighborhood greenways) more standard traffic composition were compared. Differences characteristics such as mean 85th percentile speeds, variance, proportion vehicles exceeding threshold (relative to PSL) evaluated aggregate individual scales. A series statistical hypothesis tests employed assess among data set pairs. results suggest distinct differences between treatment control groups neighborhood greenway non-greenway sites. Although there is degree variability, group experienced decreases characteristics, by greater amount than group, average. Within even likely experience larger operating speeds. These could be interpreted link-level providing indirect yet supporting evidence safety numbers motorists’ behavior greenways.