Frost Laws Taking Effect in Certain Michigan Counties

The February winter thaw has a few county road agencies activating seasonal weight restrictions across the state.

Seasonal weight restrictions, sometimes called frost laws, are to protect Michigan’s local roads from excess weight during periods when the roads are most vulnerable to damage.  State law allows the Michigan Department of Transportation, 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, trucks traveling on posted or restricted roads must reduce speeds to 35 miles per hour and carry lighter loads, a 25 percent reduction on concrete roads and 35 percent reduction on asphalt or gravel roads.

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

In 2021, the County Road Association (CRA) of Michigan released a seasonal weight restrictions app for iPhone, iPad and Android devices, as well as a revamped seasonal weight restrictions webpage. The app will allow heavy haulers to be more informed about seasonal weight restrictions, ultimately leading to safer, better roads. The app includes a refreshed color-coded map with county road agency with weight restriction info; list of restricted roads by county; list of all season roads by county; the ability to pull a permit online, directly from Oxcart; and a signup form to receive email notifications when counties make updates.

For more information on seasonal weight restrictions and for information on how to download the mobile app, visit