MI seasonal weight restrictions

The early February winter thaw has a few county road agencies activating seasonal weight restrictions across the state. The restrictions may or may not stay in effect for the rest of winter, depending on future weather patterns. Michigan law requires seasonal weight restrictions to be implemented by default March 1st, unless suspended by a county road agency.

Seasonal weight restrictions – sometimes called “frost laws” – are written into law to protect Michigan’s local roads from excess weight during periods when the roads are most vulnerable to damage. State law allows MDOT, counties and municipalities to reduce truck weights and speeds on roads that are not built to accommodate heavy truck traffic in such conditions.

During the weight restriction period, determined by each county road agency, usually in consultation with neighboring counties, trucks traveling on posted/restricted roads must reduce speeds to 35 mph and carry lighter loads – a 25% reduction on concrete roads and 35% reduction on asphalt or gravel roads.

Roads are particularly vulnerable now, in a few counties, because the milder temperatures have allowed the surface to thaw, causing water to puddle on and under the road – while the lower levels remain frozen. The now-spongy surface directly under the roadbed does not provide optimal support, making the roadbed very vulnerable to cracking under heavy loads.

The County Road Association (CRA) of Michigan also urges companies and individuals hauling heavy loads to stay away from the edge of the road. The road’s edge and gravel shoulder are the weakest parts of the road and can easily break or fail.

To see a map of counties with seasonal weight restrictions, visit micountyroads.org under the “Business” tab.

The 83 members of the County Road Association of Michigan represent the unified voice for a safe and efficient county transportation infrastructure system in Michigan, including appropriate stewardship of the public’s right-of-way in rural and urban Michigan. Collectively, Michigan’s county road agencies manage 75% of all roads in the state, including 90,000 miles of roads and 5,700 bridges. County road agencies also maintain the state’s highway system in 64 counties. Michigan has the nation’s fourth-largest local road system.

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