The trail should be outsloped more at the point of the grade dip to provide a chance for the water to be channeled off the trail. Grade dips work well on slow, steadily climbing trails. Another method for protecting sloping trails from damage caused by water is armor plating. This channels the water from the uphill side of the trail, across the trail surface, and down the continuation of the drainage. It is generally better to avoid placing culvert pipes under trails, since these tend to clog with leaf litter.
Water then backs up and flows across the unprotected surface of the trail.
However, if the topography is steep enough for switchbacks to be necessary, then any type of trail construction will probably have an erosive effect on the terrain. Thus, alternative trail alignments should be considered instead of using multiple switchbacks to cope with severe elevation changes. If inclusion of a switchback cannot be avoided, a 4 foot minimum turning radius is required for walking trails and an 8 foot minimum radius should be allowed for multipurpose or motorized use trails. Switchbacks are frequently used on excessive grades. Minimizing Vandalism Careful design can reduce the damage to trails caused by thoughtless users or vandals.