Setting speed limits based on safety, not driver behavior

  • Source: SSTI
  • Date: 01/27/2020

The 85th percentile rule in speed limit setting—an arbitrary but longstanding convention—has begun to weaken in recent years, with new guidance now allowing for lower speeds. FHWA’s USLIMITS2, for example, allows for speeds down to the 50th percentile in certain cases.

Now there’s a growing push to take observed vehicle speed out of the speed limit equation entirely.

Such is the approach that NACTO will recommend in a forthcoming practitioners’ guide. NACTO’s Jenny O’Connell previewed the guide at this month’s TRB annual meeting.

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