Spring weight restrictions go into effect on MDOT roads this morning. The Michigan Department of Transportation put the limits in place in hopes of protecting roads from the freeze-thaw cycle. Administrators say when roads have been frozen all winter and begin to thaw they are more susceptible to damage and can cause potholes. The restrictions are on all state roads, which are usually marked with an M, I or US, from the Michigan-Ohio and Indiana state line north to M-20 and M-61 in mid-Michigan. Weight restrictions for county roads in St. Clair County begin Thursday.