With the recent spike in trail users, developing sustainable trails is even more imperative to the longevity of our beloved outdoor environments. Increased traffic can mean accelerated erosion, which can be detrimental to the trail and even surrounding wildlife if the trail is not designed and built to handle the increasing levels of traffic.
A sustainable trail design should support current and anticipated user volume with minimal impact to natural and cultural resources, as well as the aesthetics of the area.
A sustainable trail should:
- Meet the current and anticipated traffic of users
- Help preserve and protect the natural flora and fauna
- Require minimal maintenance over time
- Help minimize visitor conflict between different user types, such as hikers versus mountain bikers
Planning a Sustainable Trail:
Sustainable trail design starts with receiving permission and a great deal of planning.
In the planning phase:
- Start by looking at the bigger picture – what native wildlife and vegetation will be affected by this trail? The trail(s) should have minimal impact on natural resources, cultural resources and soil.
- Communicate early with community members and seek their support – do your ideas complement their desires, needs and ideas of the community?
- Get inside of the trail user’s head.
- A sustainable trail is built with the user in mind so that the trail can support their needs. Ask yourself, “is this trail for pedestrians, mountain bikers, equestrians, off-highway vehicles (OHV’s) or peak baggers trying to summit in the shortest distance possible?” Depending on the type of user, it is essential to determine if your trail will be single or shared-use and if it is directional or bi-directional.
- Read our recent blog on “Directional Trails” for more information.
Trail Erosion Considerations
Before even thinking about digging, consider how the climate and soils may increase erosion and affect your trail. Erosion can be expedited by trail users, extreme dry conditions, water, and gravity especially where grades exceed the recommended maximum grades for various types of soil.
- Trail users: Ensure your trail can support the anticipated trail traffic so that the trail does not become braided, puddled or pocked with holes and ruts from regular use.
- Water: Water will inevitably flow downhill, following the path of least resistance, otherwise known as the fall line. Avoid fall line trails and flat areas. Ensure you evaluate the size of the watershed and climate you’re building in.
- Gravity: Use gravity to your advantage by building your trail using the Five Essential Elements of Sustainable Trails listed below.
Planning ahead to mitigate erosion will lead to minimal maintenance in the future. Erosion can destroy not only the trail but the environment surrounding the area so do your due diligence in building a sustainable trail.
The Five Elements of Sustainable Trail Design
When designing your trail, you will want to be mindful of The Five Essential Elements of Sustainable Trail Design. Here are the five elements, explained:
The Half Rule
The Half Rule: The trails grade should not exceed half the grade of the hillside or slide slope. This rule is ideal for escaping fall lines. Some soils may need to follow a quarter rule.
The Ten Percent Average Rule
The Ten Percent Average Rule: Considered to be the most sustainable option, maintaining an average trail grade of 10% or less is ideal to:
- Minimize erosion caused by users
- Applicable in most soil types
- Accommodated undulations (grade changes) in a rolling contour design
Maximum Sustainable grade
Maximum Sustainable Grade: The steepest portion of the trail that is more than 10 feet in length is considered to be the maximum sustainable grade. There are eight variables to consider when determining the maximum trail grade:
- Number of users
- Types of users
- Trail difficulty level
- Presence of rock
- Soil types
- Half rule
- Annual rainfall
- Grade reversals
Grade Reversals
Grade Reversals: A grade reversal is when a climbing trail levels out and then changes direction before rising again. They are great at forcing water to drain off the trail at the grade reversal’s lowest point, even if the trail tread becomes compacted and dished out over time.
Outslope
Outslope: As trails curve around hillside, maintain an outslope, or a slight downward tilt away from the high side, of around 5%. This allows water to come off the trail instead of funneling along the trail path. In trails optimized for mountain bikes, more insloping of tread is used requiring more attention to water drainage off trail.
Trail Maintenance
Trail sustainability is an ongoing process with maintenance being just as important as the planning. The maintenance of the trail starts with using proper Best Management Practices (BMP’s) during the build. After the construction, it’s time to routinely monitor the trail and take care of any issues sooner than later.
- Assessment: Assess the conditions of the trail by walking or riding the trail yourself and determining what problems you are facing. Address critical problems immediately and return to smaller problems later.
- Maintenance: Maintenance requires monitoring soil movement, vegetation, tree clearances, loose rocks and exposed roots.
- Trim vegetation routinely to keep the trail corridor clear.
- Cut and remove downed trees that pose a hazard to users.
- Remove any rocks that become loose after the build as they may cause injury to trail users.
- Exposed roots can be a fun challenge for bikers but it could also mean an erosion issue is occurring. Address root issues especially ones where your foot can get caught underneath the root.
Dealing with issues on your trail before they get out of hand is critical to maintaining a sustainable trail and minimizing long-term costs. Trail maintenance can be a tedious task, so contact our team of trail maintenance professionals to help manage your trail.
Trail sustainability starts by taking the time to address and assess everything – from planning and design to maintenance. There are shortcuts to trail building, but time will tell you how costly that can be, so take each step slowly and thoroughly to save time and money in the long run.
Lastly, keep in mind the bigger picture (aka the wildlife and plants), after all we are ultimately trying to balance nature with human nature. For information on trails we have worked on, check out our portfolio. For any questions or concerns about sustainable trail design, contact us!
