FAQ: Tips and Techniques for using Crusher fines surfacing for trails

Finely crushed rock (crusher fines) is a useful alternative to paving trails that accommodates most trail activities.

by American Trails Staff

Crusher fines is a finely-crushed stone mix that is often the byproduct of gravel operations. Crushed stone trails provide a user-friendly, all-season surface for all types and ages of visitors, including strollers, wheelchairs, and road bikes. If built properly crushed stone trails can meet the specification for a "firm and stable" surface as defined in current federal guidelines for accessible trails.

Best Practices:

  • For use in trail surfacing, the material should be composed of irregular angular particles that interlock and bind into a firm matrix.
  • The rock particles should range in size from dust to 3/8 inch.
  • Gravel and crusher fines differ from one another in that gravel is screened to remove the fines which contain the natural binders/cements.
  • Crusher fines applied over landscape fabric to a depth of 4-6 inches.
  • Accessible crushed stone trails should be designed and constructed at grades less than 8% grade to promote accessible use.
  • Overall trail grade averages of less than 6% will provide the most user-friendly experience and offer the most sustainable natural trail surface if compacted crusher fines are to be used.
  • Be sure your material is crushed rock, not volcanic cinders, "red breeze," decomposed granite, pea gravel, or river rock.

Recommend Resources

The Art of Building Crushed Stone Trails

Crushed stone trails provide a user-friendly, all-season surface for all types and ages of visitors, including strollers, wheelchairs, and road bikes.

Photos highlighting the pitfalls and best practices of crusher fines

Typical crusher fines surface showing very firm matrix with only a few loose larger rock particles.

Water running down the slope gathers on the crusher fines trail because of insufficient cross slope of the trail.

A better crusher fines trail in the same Bluff Lake Nature Area, Denver

Here the edging keeps water from draining so obstacles in the form of drainage bars were placed to try to keep the crushed rock from eroding.

Horses, bikes, and walkers all use the crusher fines Highline Canal Trail near Denver, CO.

Top quality crusher fines trail along the Highline Canal in Cherry Hills Village, CO.

The fabric used under the crusher fines is exposed because of insufficient depth of material; Big Dry Creek Nature Trail, Westminster, CO

Crusher fines trail built up to form a bench; Lomaki Wupatki National Monument, AZ

Crusher fines will eventually dry smooth once snowmelt stops; Adams County, Colorado, park.

Crusher fines trail lined with native rock; Lomaki Wupatki National Monument, AZ.

A fine grained, dark crusher rock is the surface for trail at Westerly Creek Dam, Denver.

Crushed rock that is larger and looser than ideal; Bluff Lake Nature Area, Denver.

The plank edging is supposed to keep the crusher fines in place; Big Dry Creek Nature Trail, Westminster, CO.

Trail climbs at a low angle up the face of Westerly Creek Dam, Denver.

Crusher fines trail on top of the Westerly Creek Dam, Denver.

The landscape fabric is exposed in this Philadelphia park due to runoff: the trail runs straight down the slope.

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