reduced by installing root barriers during the sidewalk construction to prevent the roots from growing beneath the slab.

Fig. 5.1: Uplifting Caused by Tree Roots
( www.ci.middleton.wi.us , www.oneilstreeservice.com )

5.2   Heavy Load

Sidewalks are not designed to carry large loads. They are meant to support the weight of people, bicycles, snow and some light machinery. When the sidewalk is subjected to unexpectedly large loads, failure occurs producing cracks which propagate with repeated application of the load. Typically, this is an issue where sidewalks occur at driveways; however, sometimes sidewalks are used inappropriately (as shown in Figure 5.2). It may not be obvious that heavy loads are the cause of some cracks unless the cause was observed during the inspection.

Fig. 5.2: Some Examples of Heavy Loads on Sidewalks ( writog.blogspot.ca , www.io.com )

5.3  Age

If the sidewalks are not subjected to unexpected loads or tree roots, it is most likely that deficiencies were caused by age. Factors affecting the aging process of sidewalks include weather, fatigue, the freeze-thaw cycle, erosion and use. Spalling and chipping are other common deficiencies caused by age and improper placement practices (see Figure 5.3).