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Three basic designs for sidewalk cutouts
It is very expensive to plant trees in sidewalk and pavement cutouts. Money is often wasted on poorly conceived plans. There are three basic methods of designing sidewalk cutouts. Each has associated costs and benefits to the community.
For communities with a short-term view
Design the site so roots essentially remain in the small soil area of the cutout (this is most common).
- Result: Tree grows slowly, dies and is replaced 5 to 10 years after planting; the sidewalk stays mostly intact.
- Costs: Inexpensive to install; recurring but known cost of replacing tree every 5 to 10 years.
- Community benefit: Little. Trees are rarely healthy and never become large; they provide little shade. This is a poor investment because money is spent with little benefit to anyone.
For communities with a medium-term view
Design the site so roots grow out of the soil in the cutout and into the soil under the walk.
- Result: Tree grows well and is fairly healthy, but sidewalk often heaves and the tree is blamed.
- Costs: Larger initial cost; recurring costs and root damage from fixing pavement.
- Community benefit: Significant. Tree grows well and becomes large, providing significant shade, but is often damaged during pavement repair.
For communities with a long-term view
Design the site so roots grow out of the soil in the cutout and into the soil under the walk in an engineered fashion.
- Result: Tree grows well and is healthy; sidewalk remains intact.
- Costs: Largest initial cost but no recurring costs.
- Community benefit: Significant. Tree grows well and becomes large, providing significant shade.
No studies have done this cost-benefit comparison, but it would not be surprising if the long-term costs of each of these three strategies were similar. If this is the case, it makes little sense to pursuit the now-common short-term strategy.
