Michigan House bill would revise speed limits rule

January 17, 2023

Keith Goble


A Michigan state lawmaker has reintroduced a bill that is touted to address “flaws” in how local roadway speed limits are set.

Michigan law states that an engineering and safety study be conducted to modify a speed limit. Additionally, speeds on state and local roads must be rounded to the nearest multiple of 5 mph.

‘Flexibility’ for setting speeds

Rep. Bradley Slagh, R-Zeeland, is behind a bill to update how the state observes the 85th percentile speed rule – the speed at or below which 85% of vehicles travel in free-flowing traffic.

Specifically, his bill would give the state flexibility to round down the 85th percentile speed when necessary. Specifically, local officials could set the speed to a multiple of 5 mph within 5 mph of the 85th percentile instead of the nearest 5 mph.

Slagh uses the example of the 85th percentile speed on a roadway with an average speed of 37.6 mph. His bill would give the state flexibility to set the speed at 35, instead of being required to bump it up to 40 mph.

“I’ve listened to community officials who are frustrated by the existing method because it bases local speed limits solely on metrics, not on commonsense factors, such as pedestrian safety, road visibility obstructions, or proximity to parks and playgrounds,” Slagh said in a news release. “We must make this very simple change to state law to empower communities to keep all road users safer.”

The legislation also would remove the requirement of an engineering and safety study to be conducted to alter a speed limit. Instead, a modified speed limit could be determined in accordance with traffic engineering practices that provide “an objective analysis of the characteristics of the highway.”

Additionally, the bill would permit a speed limit to be set below the 85th percentile if an engineering and safety study showed a situation with hazards to public safety that is not reflected by the 85th percentile speed. A speed limit could not be set below the 50th percentile speed.

One year ago, House lawmakers approved the change but the bill died in the Senate Transportation and Infrastructure Committee.

This year’s bill, HB4012, has moved to the House Transportation, Mobility and Infrastructure Committee. LL

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