TRAIL BUILDING GUIDELINES

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left 12 right

MULTI- USE NON-PAVED TRAILS

Cross-section

1. Full bench construction on slopes exceeding 20 percent. (No fill to be used for the trail tread.)
2. Minimum tread width - 3' to 4'. (The length of a pulaski.)
3. Outslope (cross slope) - 2% to 5%.
4. Travelway clearance - horizontal - 8', vertical - 10'.

Grade

1. Sustained grade - 8% or less.
2. Maximum grade - 10% for less than 100'. (Only in rare and unusual circumstances should new trail be constructed in excess of 10% grade, maximum 15%.)

Water management

1. Terrain features, rolling grade, and reinforced grade dips should be built into new trails instead of structures such as waterbars, for directing water off of the trail.
2. Do not install drain dips in an existing trail when grades exceed 10%.
3. Waterbars should be constructed of rock or pressure treated 4" to 6" diameter logs positioned at 45 to 60 degree angle to the trail. Water should run off before hitting the waterbar. The water run out area outlet should be at least two to three shovel blades wide (2' to 3'). Waterbars should rise no more than 1" to 3" above the level of the trail tread.

Switchbacks

1. Turning platform - Minimum radius 6' from the inside of the turn, 0 to 5% outslope.

MULTI-USE PAVED TRAILS

Tread width

1. Minimum tread width is 10' (Only in unusual circumstances should 8' width be considered).

Bridge width

1. Should be the same as the trail tread width.

Outslope (Cross slope)

1. Should be 2%.

Sub-base (These are general specifications. Final specifications should be based on soil tests.)

1. 6" to 8" untreated base course 3/4" minus Compacted to 95%.
2. (Washington County) - No less than 4" untreated base course ½" or 3/4" minus.

Asphalt

1. Hot mix asphalt (HMA), dense-graded, laydown (near voidless).
2. Thickness - 2 ½" to 3".
3. Aggregate size 9.9mm or ½" minus.

TRAIL HEADS

Sub-base

1. 8" untreated base course 3/4" minus. Compacted to 95%.

Asphalt

1. Thickness - 3".

Dimensions (if there is equestrian use)

1. Suggested minimum 100' X 130'.

The following trail feature images courtesy of the International Mountain Bicycling Association, taken from their publication Trail Solutions.