Standards and Procedures:
Trail Assessment

Trail assessment - that is, the ability to analyze a section of trail and determine its maintenance needs - is a foundational skill of trail maintenance, but can be tricky to learn. When starting out, it is normal to rely on the leadership and expertise of more experienced maintainers to identify specific project needs. As you become more proficient at basic techniques, eventually the opportunity arises to gain more independence and leadership potential of your own by learning to identify the needs of the trail with your own eyes.

Developing skills of trail assessment, often called “trail eyes,” takes training and practice. Many factors need to be taken into account - some obvious and others very subtle. The first step is developing a knowledge and understanding of trail work standards. It is impossible to properly assess a trail's drainage features or tread conditions without first being familiar with the desired standards. Before assessing, be sure to refresh yourself on the trail work standards found in the sections of this website: in particular Tread Work, Drainage, Brushing, and Class Specifications.

After studying the basic principles, a good way to learn trail assessment is to go out and simply practice on your own. Assess a section of trail and formulate your maintenance proposals. It is best to then compare notes with an experienced maintainer to see how you did, what you might have missed, etc.

Keep in mind that the most important element to study while assessing trails is the impact of water. More than any other single factor, poorly managed drainage will take a trail from one which can be maintained to one which will be degraded beyond repair.

Good trail assessment is a particularly valuable skill for volunteers in the Pisgah Ranger District. With approximately 400 miles of trail to maintain, it is not feasible for USFS staff to keep eyes on all trails at all times. Volunteers often form the frontline of assessment and identification of maintenance needs.

Key Points:

- Water 
- Brushing
- Tread 
- Structures
- Trail Triage

See Also:

- Tool/PPE Guidelines
- Additional Resources

 Assessing for Water


- Look for:
   + Current drains and water bars: are they open and wide, or are they full of sediments and debris?
   + Locations where new drains could be installed.
   + Areas where erosion is particularly intense.
   + Sections where the berm is a problem, channeling water down the middle of the trail.

- Identifying drainage concerns is the most important factor in maintaining trails - catching problems early means they can be mitigated. Left unchecked, drainage problems will destroy a trail and it will require the lengthy process of relocation.



- As you assess the trail, look carefully at the tread and try to imagine water flowing. Get into the “mindset” of water flowing down the trail.

- Look for signs of erosion - exposed, loose rocky material on the surface of the tread shows where smaller sediments are washing away. Look for flat areas of fine sand and silt where water has been pooling and depositing the sediments. Cupped/gullying sections show you where erosion is actively taking its toll.

- One of the best ways to assess water-related trail issues is to go for a hike in the rain. You will see firsthand how water is behaving. Take note of where water is pooling, channeling, flowing. Is water sheeting across the tread as it should? Are drains effectively diverting water off the trail? Are there muddy sections you’d rather walk around?

- Considering topography, where can water be taken off the trail relatively easily? Where will it be challenging, but necessary?

- Take care to mark the locations of water issues you discover while assessing in the rain or shortly after heavy rain. Oftentimes problem spots are less obvious when the conditions are dry.

Assessing for Brushing 


- Overgrown brush is generally easier to visualize than water issues, but if neglected will still lead to problems. If vegetation pushes users to the outside edge of the trail it will lead to degradation.

- Look for:
   + Woody vegetation encroaching from the uphill side of the trail (rhododendron and laurel are common culprits).
   + Overhanging vegetation that gets in the way of users.
   + Potential problem vegetation that could become problematic if left unchecked (small saplings, etc).
   + Brushy vegetation encroaching into the treadway from both sides.


- Notice the way you are walking on the trail in response to vegetation. Are you moving to one side or another? Are you ducking to the side to avoid brushing up on an overhanging branch? Even gentle, leafy twigs can subtly push users to one side.

- Think in terms of “preventative maintenance.” Can you identify saplings and branches that may not be causing a problem now, but if left unchecked will eventually encroach on the trail?

- Take note of what kinds of tools would best address the brushing needs on a particular stretch of trail. For larger woody brush, consider folding saws or even chainsaws. For lighter pruning work, a mix of saws and loppers. For extensive stretches of smaller brushing, consider motorized brush cutters to take care of the bulk of the work, using folding saws and loppers to supplement in hard to reach areas or for isolated larger plants.

- Prioritize trails with clearly overgrown brush, or where brush is visibly contributing to trail creep.

- Consider line-of-sight concerns on bike-accessible trails. If brush is obstructing visibility it can create a safety concern, which must be mitigated.

Assessing Tread


- Closely tied with water issues, the tread itself needs to be carefully assessed to determine basic maintenance needs.

 - Look for:
   + Berms forming on the outside edge of the tread, creating a cupped tread that will channel water.
   + Sloughage, where sediment is sliding down from the backslope and forming a mount along the inside edge of the tread - this can push users toward the outside.
   + Problematic root growth extending from the uphill side that will push users toward the outside.
   + Collapsing banks
   + Excessive grades (generally above 12%)
   + Social trails or shortcuts - have users been going off of the designed trail route? Why are they doing this?


- Pay close attention to the way you are walking or riding on a trail while doing an assessment. Are you traveling in the center of the tread (the ideal) or are you being subconsciously pushed to the edge?

- Pay close attention to the shape of the tread. Take note of stretches where berms and/or sloughage are creating cupped trails and make note of these sections. Catching a problem early can save a lot of work in the long run.

Assessing Structure Needs 


- Learning when and where to install a structure, and then determining which structure to apply, can be a tricky job, sometimes with more than one right answer (although some right answers are inevitably better than others).

- Structures take a lot of logistical planning and resources to build, so an important part of trail assessment is learning when structures are really necessary, or whether drainage and tread solutions would be adequate and more efficient.

- Look for:
   + Very steep sections with signs of resource damage. This typically occurs on grades over 10-12% and will be evidenced by cupping/gullying.
   + Short, isolated sections of heavy resource damage typically with a specific cause. If dealing with a lengthy, extensive section of unsustainable, degraded trail, relocation may be a better investment of resources compared to building structures.
   + Areas of steep, unstable, or collapsing banks that threaten to collapse, completely compromising the tread and potentially creating safety hazards.
   + Standing water in flat areas where drainage is not feasible.
   + Sections of fall line trail where effective drainage is difficult or impossible.


- Assessing for structures is a more advanced skill that comes with experience of building various types of structures, and understanding the strengths and weaknesses of each one.

- Consider the types of material you may be able to harness in the area. Are there any black locust trees in the area? If so, how simple or complex a felling situation will it be? Is there rock available within the corridor?

- Consider logistics for vehicle access, including UTV access, which could expand possibilities by importing materials like gravel, locust logs, or lumber.

Trail Triage


- There will always be more work than there is available time or labor. Making choices about what to prioritize first versus what can be deferred is therefore extremely important. This is especially true of larger projects that require USFS approvals and assistance.

- General Priority Levels:
   + URGENT: User safety is threatened
   + High: Severe erosion or resource damage established
   + Moderate: Significant erosion or resource damage has begun
   + Low: Beginning of a problem, signs of trouble. Not currently much damage.


- “Tipping Point” Principle

- As a general rule, prioritize trails that can be repaired before they are too far gone before addressing those that are degraded to the point of requiring major resources, relocation, funding, etc.

- Once trails reach the “tipping point,” they are so badly degraded that the amount of time, materials, and labor required to rehabilitate them will most likely not be available. Salvaging those trails that are degrading, but haven’t hit the tipping point yet, is the best use of volunteer efforts.

Tool and PPE Guidelines


Basic trail assessment can be undertaken with nothing more than your eyes, your brain, and something to record information. The following tools can be helpful to gather more information.

- Notebook or alternative record device
- Map
- GPS-enabled phone or device - providing accurate locations for problem areas is extremely helpful. Most smart-phones are able to collect GPS even while offline. A variety of downloadable apps, both free and paid, can enable GPS data collection. 
- Camera or camera-enabled phone 
- Clinometer
- Tape measure


Unless you've brought tools along and plan to do maintenance, no PPE is required for conducting trail assessments. 

Additional Resources

Trail Fundamentals and Trail Management Objectives - This manual from USFS outlines the criteria by which trails are designed, assessed, and managed.  While a lot of the manual is geared for USFS trail managers, the general principles on Trail Class and Designed Use are important for any maintainer to understand.  For key guidelines on these principles, check out the Pisgah Trail Academy page on Trail Class Specifications.