The Michigan Department of Transportation is now implementing “frost laws” to help protect roadways. Better put, frost laws are weight restrictions for trucks on roadways, which can damage the highway and road system.
The new restrictions went into effect at 6 a.m. on February 2, 2024. They imposed restrictions on all trucking highways throughout the state. All trucks have weight restrictions that are to be enforced.
When roads that have been frozen all winter begin to thaw from the surface downward, melting snow and ice saturate the softening ground. During the spring thaw, the roadbed softened by trapped moisture beneath the pavement, making it more susceptible to damage. This contributes to pothole problems due to this winter’s numerous freeze-thaw cycles.
In the restricted areas, the following restrictions apply as of February 2, 2024:
Legal axle weights are not reduced on routes designated as “all-season” (designated in green and gold on the MDOT Truck Operators Map).
All extended permits will be valid for oversized loads in the weight-restricted area on restricted routes. Single-trip permits on the restricted routes will not be issued for overweight loads or loads exceeding 14 feet in width, 11 axles, and 150 feet in overall length.
On routes designated as “seasonal” (designated in solid or dashed red on the MDOT Truck Operators Map), rigid (concrete) pavements will have a posted weight reduction of 25%, and flexible (asphalt) pavements will have a posted weight reduction of 35%, and some vehicles will have a maximum speed of 35 mph. Drivers must follow the speed limits for weight-restricted roads, per state laws.
In terms of county road commissions and city public works departments, they establish their own seasonal weight restrictions, which usually, but not always, coincide with state highway weight restrictions. Signs are generally posted to indicate which routes have weight restrictions in effect.