Greater widths may be needed on downhill grades. Drainage Multi-use paths must be constructed with adequate drainage to avoid washouts and flooding, and to prevent silt from intruding onto the path. Path adjacent to trees All vegetation, including roots, must be removed in the preparation of the subgrade. Special care is needed to control new growth, such as the use of soil sterilant or lime treatment of the subgrade. Plants that can cause other problems should be controlled, such as plants with thorns that can puncture bicycle tires.
Paths built in wooded areas present special problems.
The roots of shrubs and trees can pierce through the surface and cause it to bubble up and break apart. Preventive methods include removal of vegetation, realignment of the path away from trees, and placement of root barriers along the edge of the path. A separate soft-surface jogger or equestrian path may be constructed with bark mulch alongside the paved path. Where a connection is needed to a destination or another path at a different elevation, a stairway can be used where the terrain is too steep for a path. A grooved concrete trough should be provided so bicyclists can easily push their bicycles up or down.