Urban landscape design often requires practical interaction with people, animals, vehicles and infrastructure. A functionally designed landscape allows for work, travel, safety and recreation.
The expected functionality of a site is linked to its purpose and its landscape design will correlate accordingly. On a strictly practical level, functionality should be the first and most important consideration in sustainable landscape design.
Use retaining walls to avoid steep slopes.
Plan practical widths for sidewalks, paths and driveways.
Have correctly spaced stepping stones.
Select and place plants as to preserve necessary clear site lines.