In the spring, the surface of the roadway begins to thaw while the base material below is still frozen. This frozen layer underneath the road prevents moisture from draining properly through the soil as it does other times of year. The trapped moisture causes the soil just beneath the roadway to become weak and if larger loads are allowed on the these roads, severe and permanent damage can be done to the roadway.

During this time, trucks can haul but it must be at a reduced weight. Typically road construction crews wait until after the load restrictions are lifted because it can be very difficult to efficiently move materials during that time.

Also protection of the roadway on the detour route is also a factor. For state highways the maximum amount of time spring load restrictions can be on is eight weeks. The road restrictions in South East Minnesota went on March 6, so May 1 would be the latest they would be lifted. One caveat to that is the local road authorities, such as counties and city can keep the restrictions on longer if they so choose.