When the water table is very high as in the case with a wet fall like that of 2006 or 2005 the ground is super saturated with water which can be just below the surface or a few feet down. Winter freezes over the surface and things will move along just fine on top of the frozen ground, especially ground with lots of moisture.
However, once the spring thaw begins the warm temperature on the surface causes the frost to move down. Water which had been a liquid well below the surface is then frozen and that poses serious problems to anything and everything around as water expands considerably when it turns to ice. The result is that if that body of water is below a paved or hard surface of a road the hard surface is destroyed.
During the mid 1950s Saskatchewan's roads were mostly made from just plain old dirt which could absorb a lot of water and in the spring of those "wet years" the roads and highways of Saskatchewan were destroyed. Since then road and street construction has been changed to make sure the base material is plastic enough to handle wate, liquid or frozen and thus reduce damage to the surface. However, there are still lots of parking lots, town streets, country roads and even some highways that still have top soil mixed in below the surface and on a wet spring the road or surface above will crumble as a "frost boil" expands below and destroys the surface.