pavement surface exhibits depressions as a result of compaction/mix design problems. Sub grade rutting occurs when the sub grade exhibits depressions due to loading. In this case, the pavement settles into the sub grade ruts causing surface depressions.

Fig. 4.4 Rutting in Asphalt ( halifax.ca )

4.5 Uplifts

4.5.1   Uplifting

Because of the weather conditions in Windsor, the soil under the sidewalk expands and contracts during the freeze-thaw cycle. This effect, as well as tree roots, causes sections of the sidewalk to move vertically, creating a trip hazard. This typically occurs along joints or cracks in the sidewalk.

The height of the uplift determines its severity as outlined below: