Jessica Mathews / news@whmi.com


The Michigan Department of Transportation and local agencies are enacting spring weight restrictions Friday - an annual move to protect roads.

Effective 6am Friday, weight restrictions will be imposed and enforced on all state trunkline highways in the entire state of Michigan. State routes typically carry M, I, or US designations.

When roads that have been frozen all winter begin to thaw from the surface downward, melting snow and ice saturate the softened ground. During the spring thaw, the roadbed softened by trapped moisture beneath the pavement making it more susceptible to damage. That contributes to pothole problems already occurring due to this winter's numerous freeze-thaw cycles.

In the restricted areas, the following will apply:

-On routes designated as "all-season" (designated in green and gold on the MDOT Truck Operators Map), there will be no reduction in legal axle weights.

-All extended permits will be valid for oversize loads in the weight-restricted area on the restricted routes. Single-trip permits will not be issued for any overweight loads or loads exceeding 14 feet in width, 11 axles, and 150 feet in overall length on the restricted routes.

-On routes designated as "seasonal" (designated in solid or dashed red on the MDOT Truck Operators Map), there will be a posted weight reduction of 25 percent for rigid (concrete) pavements and 35 percent for flexible (asphalt) pavements, and maximum speed of 35 mph for some vehicles.

Drivers must follow the speed limits for weight-restricted roads, per state law, for speed restrictions for trucks, and the rules for propane fuel delivery and public utility vehicles.

MDOT determines when weight restrictions begin each spring by measuring frost depths along state highways, observing road conditions, and monitoring weather forecasts. Weight restrictions remain in effect until the frost line is deep enough to allow moisture to escape and the roadbeds regain stability.

County road commissions and city public works departments put in place 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.

For weight restriction information and updates, call 800-787-8960. Information can also be accessed via the provided web link.