Winter Park staff lays out data-driven speed study method and thresholds for traffic calming

At the task force meeting, staff described a standard field-data process: install traffic counters, collect speed and volume data, compute the 85th percentile speed and compare findings against set thresholds to determine whether a roadway is warranted for traffic calming.

"We will then determine what the 85th percentile speed is," the presenter said, and added the thresholds used by Winter Park: 7 miles per hour over the speed limit on local streets and 10 miles per hour over the speed limit on collector streets. Staff said the city references a National Association of City Transportation Officials publication for guidance and noted that the method provides guidance rather than a legally defensible standard. Staff also described before-and-after studies (about six months to a year) to confirm whether interventions achieved intended outcomes.