NDOT proposes speed cushions, studies speed tables for Harpeth Bend Drive after 85th‑percentile speed measured at 43 mph

NDOT staff presented a traffic calming concept for Harpeth Bend Drive on a segment between Highway 100 and McPherson Drive and outlined next steps toward a neighborhood ballot and construction if the vote succeeds.

Amy Burch, a traffic engineer and consultant working with NDOT, told residents that data collection showed an 85th‑percentile speed of 43 miles per hour on Harpeth Bend Drive where the posted speed limit is 25 mph. “So 85% of the traffic on Harpeth Bend Drive is going 43 miles per hour or below,” Burch said, adding that 15% of vehicles were measured going above 43 mph. She also said measured average daily volume for the segment is about 1,392 vehicles per day in both directions and that the corridor has 10‑foot lanes, bike lanes and no sidewalks.

The concept plan presented by NDOT calls for eight sets of vertical devices—typically speed cushions—spaced about 530 feet apart along the project limits. Burch said the cushions proposed for Harpeth Bend would be 14 feet long to be smoother for drivers and that flexible delineator posts would be placed to discourage drivers from moving into the bike lane to avoid devices. She explained NDOT’s typical spacing guidance: “As we place them in spacing of around 500 feet, then drivers will have to essentially stay the same speed consistently along the length of the street without picking up speed and slowing that down real fast.”

NDOT staff described the…