MI HB4733

Amends Section 628 of the Michigan Vehicle Code to revise procedures for establishing speed limits on county highways, limited access freeways, trunk line highways, and local highways.

Speed limits must be determined by the 85th percentile speed of free-flowing traffic under ideal conditions, rounded to a multiple of 5 mph and within 5 mph of the 85th percentile speed.

Allows incorporated cities and villages to set speed limits below the 85th percentile if an engineering and safety study by a licensed professional engineer demonstrates hazards threatening public safety, but not below the 50th percentile under any circumstance.

Requires traffic control orders establishing modified speed limits to be filed with the county clerk (for county/state highways) or local administrative office (for local highways) and to serve as evidence of authority in court.

Removes previous requirement that speed limits not be posted below the 50th percentile speed and updates design speed reference standards from the 2011 sixth edition to the 2018 seventh edition of AASHTO geometric design guidelines.