LANSING — Local transportation agencies, including the road commissions of Mecosta, Lake and Osceola counties, enacted seasonal weight restrictions this week.

Weight restrictions were imposed and enforced beginning at 6 a.m. Monday on all roads in the three counties, outside of those which have been specifically exempted.

When roads that have been frozen all winter begin to thaw from the surface downward, melting snow and ice saturate the softened ground, according to a news release from the Michigan Department of Transportation (MDOT). During the spring thaw, the roadbed softened by trapped moisture beneath the pavement makes it more susceptible to damage. This also contributes to pothole problems already occurring due to this winter's numerous freeze-thaw cycles.

For state roads, 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.