[From Jessica Roberts on the TDM listserv]
NACTO released a new guide https://nacto.org/safespeeds/ on how to set speed limits in urban areas. The TL;DR version is:
*City Limits* outlines a three-method approach to speed limit setting that provides an alternative to percentile-based speed limit setting:
1. *Setting default speed limits* on many streets at once (such as 25 mph on all major streets and 20 mph on all minor streets), 2. *Designating slow zones* in sensitive areas, and 3. *Setting corridor speed limits* on high priority major streets, using a *safe speed study*, which uses conflict density and activity level to set context-appropriate speed limits.