Trail Categories

The purpose of trail categories is to provide information so users can select a route that may be safe and usable for them. Categories are determined by the primary elements that affect the ability to use a trail, such as type of surface, grade, cross-slope and distance between features. Each category is first defined using these base definitions but may need to be adjusted to reflect unusual conditions. Note that these categories are focused on pedestrian use and use by persons with physical disabilities or limited mobility and are separate from the mountain bike trail difficulty rating system.

⛈️ Weather conditions can alter the trail surface and may create barriers unknown to Oakland County Parks staff. If a trail is identified as having a natural surface, please be aware that after heavy rains or other weather events, the condition may temporarily cease to be firm and stable. If you encounter any barriers not described in the trail category, please let us know using our feedback form.

Green

Trail Classification: Shared Use Path

Green trails are firm and stable with a paved, concrete or compacted, crushed-rock surface and a minimum 5 feet width. Grades along these trails are 5 percent or less with cross slopes 2 percent or less. No known barriers higher than a half-inch exist within the trail tread, though weather and other unexpected events may create unplanned obstacles.

Blue

Trail Classification: Hiking Trail

Blue trails have a surface which is firm and stable with a hard/paved or compacted, crushed-rock or natural surface and are a minimum of 3 feet wide. Typical grades on these trails are less than 5 percent but can be up to 8 percent for distances less than 200 feet. Cross slopes are 2 percent or less on paved surfaces and on natural surfaces are less than 5 percent. Where there’s a sustained width of 3 feet, there are widened sections for resting areas at a maximum interval of every 100 feet. Tread obstacles are a half-inch or less on paved trails and less than 2 inches on natural surfaces.

Black

Trail Classification: Hiking Trail

Black trails are primarily natural surface, though some areas may be hard/paved or compacted, crushed-rock. Grades between 8 to 10 percent may be sustained for up to 30 feet, with cross slopes 3 percent or less on any hard surface and 5 percent or less on natural surface. The minimum tread width is 3 feet, and where there’s a sustained width of 3 feet, there are widened sections for resting areas at a maximum interval of every 200 feet. Uneven, rocky or natural tread barriers exist up to 2 inches high.

Red

Trail Classification: Rustic Trail and/or Mountain Bike Trail

Red trails are all-natural surfaces and may not be firm or stable. They are sometimes narrower than 36 inches wide with no designated resting areas and include uneven, rocky or natural barriers. Red trails may have sustained grades of 10 percent or more with cross slopes that may vary significantly. These trails may contain constructed mountain bike trail features that are 8 inches high or less.

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