Trees often ruin sidewalks, and sidewalk repair often kills trees.
This conflict comes from the fact that sidewalks and trees have competing needs. Trees need a soil that is moist and loose, and that they can push aside as they grow. Trees and sidewalks are costly and valuable, so both needs must be taken seriously. Most of the damage to sidewalks is caused as roots become thicker through secondary growth. Sidewalk damage is often caused by the soil in its expansion and contraction.