What is the Frost Law?
As the ground begins to thaw, the surface of our roads becomes unstable, buckling and heaving. It is the warming and cooling of the ground that weakens the roads creating potholes and broken pavement. To address this issue, Michigan state law designates the months of March, April and May as reduced load months for trucks. This state law is known as the 'frost law,' referring to the amount of frost remaining in the ground.
What are the restrictions?
In March, April and May trucks traveling on "posted or restricted" roads must lighten their loads and reduce their speed because heavy trucks and speed increase the damage brought by the change of season. The maximum axle load allowable on concrete pavements is reduced by 25 percent and by 35 percent on all other roads. The maximum wheel load shall not exceed 525 pounds per inch of tire width on concrete and 450 pounds per inch on other roads. The speed on reduced loading roads drops to 35 miles per hour regardless of the posted limit.
What vehicles are exempt from the Frost Law?
- Vehicles transporting agricultural commodities, which are plants and animals produced by the farmer, but not including trees or lumber
- Milk Haulers
- Farm Equipment
- Public Utility Vehicles
How do you receive exemption?
First you must request a permit from your local county road department or road commission. This must be 48 hours advance notice before you travel on the restricted roads if your truck exceeds the weight restrictions. The local authority is required to issue a permit stating the date and time of travel, the route and the maximum speed limit. There is a fee for the permit.
What if you do not comply?
The laws allow for fines and costs for violations of the seasonal weight restrictions. (MCL 257.724, 257.716)
Are all Michigan Roads affected by the Frost Law?
No. The State posts the restrictions for the roads and highways under its jurisdiction while the local authorities announce the streets and roads under their control affected by the frost law. To discover which roads in your county are affected, you can check with your county road agency or the County Road Association of Michigan: http://bit.ly/1cgEdNG.