From "Pathways to Trail Building" by Tennessee Department of Environment and Conservation
The goal of trail building is to create a long-term relationship between humans and nature.
The goal of trail building is to create a long-term relationship between humans and nature. This is only possible through a clear understanding of the needs of each trail related agency laced with a healthy dose of day-to-day reality. Planning and responsibility are the keys to success. Learning how to build a trail is an ongoing, never ending process with each section of trail to be constructed a new challenge. The trail designer/constructor learns over time the nuances of the forest, rocks and streams and how important it is to build a sustainable trail that is easy to maintain and becomes a natural part of the landscape. Sustainable trails minimize environmental impacts, are easy to travel and reduce future trail operation and maintenance costs.
Trail design is one of the most important factors to insure that the route offers optimum scenic, geologic, historic, cultural and biological sites to provide a variety of diverse habitats for the trail user to experience. Trail design is the critical connection to make the trail sustainable, to reduce impacts to the natural environment, and to minimize future trail maintenance.
The National Park Service (Rocky Mountain Region, January 1991) definition of a sustainable trail is:
1. Ridge lines: Ridgelines offer prime opportunities to avoid the high cost of trail construction with steep grades on side slopes. Ridgelines also can provide panoramic views of the surrounding countryside.
2. Bluffs and Cliffs: These steep sided gorge edges offer trail routes with few construction problems except for where large streams cut through the bluff edge. High cliffs, deep ravines and rock outcrops covered with lichens and mosses offer attractive vistas along the trail route. Main trail routes should stay away from the edge of the cliffs with an occasional short side trail to an overlook location. Overlooks should be at one–half mile to one-mile intervals if a good view is available without having to cut any trees.
3. Stream Bottoms: Streams offer both opportunities and challenges. The additional moisture in riparian environments creates conditions suitable for many plants and wildlife species not found in the surrounding upland areas. These high moisture conditions can make the trail tread muddy and will generally require the placement of stepping-stones or raising the trail tread with boardwalk structures. Trails in stream bottoms should avoid thick vegetation areas such as canebrakes, saw briar and grapevine thickets.
Areas of wet or poorly drained soils also should be avoided. Advantage should be taken of any natural “benches” or terraces running along the bottoms of a gorge that may be adjacent to a stream.
4. Points of Interest: A well-designed trail should include as many points of interest as practical and feasible along the length of the trail. Some points of interest may include:
If potential overuse of these sites is an issue, routing the main trail away from the feature and providing access with a spur trail will reduce the amount of impact to these points of interest.
This section deals with the equipment needed and procedures for selecting, marking and identifying the trail route in the field. Trail sustainability is the primary goal of trail layout with ease of construction as a secondary goal. If constructed properly, trail tread stability can be maintained indefinitely, even over steep slopes and rocky areas.
1. Materials and instruments:
a. Plastic surveyors tape - Different colors (orange, red, blue and white) are useful for trail marking purposes. Use the blue to mark the main trail, red to mark control points such as road/trail junctions or stream crossings and orange for points of interest such as overlooks, waterfalls or unique natural features. Carry a black permanent marker to write notes on the tape if needed. This type of tape can be found in some hardware stores and can be ordered from companies like Forestry Suppliers, Ben Meadows, etc. Check the picture on the front cover to note the white flag between the 2nd and 3rd trail workers.
A recommended method of marking the trail route with flagging tape is to wrap the tape around the tree twice and tie the knot on the side of the tree the trail will pass. Leave a tail (piece of flagging tape 12-18” long) to help identify the knot. Whatever method to mark the trail is chosen, be consistent, so there are no questions where the trail route is located and tread construction is to take place.
b. A compass is still a useful tool to guide the trail planner for topo map orientation and to find control points and determine which ridges or stream valleys to follow.
c. A clinometer with a percent scale is used to determine the percent grade ascending (positive) or descending (negative) as the trail route is marked.
d. A 25-foot tape measure is used to determine trail corridor width and to calculate tread width on graded trails.
2. Field Reconnaissance:
Maps and other equipment are only tools to assist in the on site visit to a potential trail location. Exploring the area through which the trail is to be routed is very important and needs to be done several times before selecting the preliminary route. Important items to concentrate on when exploring the area include the following:
a. Points of interest – Interesting features may be identified on the map and located by on-site inspection. Draw in the additional interesting features that are not on the map.
b. Stream Crossings - Stream and road crossing(s) need to be researched thoroughly due to the potential dangers and importance of these points on the trail route. Streams are subject to water fluctuations sometimes as much as 5-10 feet or more and a bridge may be necessary to cross a creek. Extensive scouting to find the best location for the bridge site is very important and the lowest part of the bridge should be 5-10 feet above the highest flood level. The managing agency must approve any bridge design that would be built on the trail.
c. Road Crossings - Careful location of is very important. Visibility on road crossings with heavy traffic should be a minimum of 500 feet in both directions. Check with the managing agencies or the state Department of Transportation when considering a road crossing.
d. Level areas - Since long straight trails are not aesthetically pleasing, design slight right and left curves into the trails to avoid a highway effect. Sight distance should be 50-100 feet ahead of the trail user.
e. Steep hillsides - Steep areas present situations where careful trail location and design is essential. When possible, avoid locating trail routes on steep slopes. However, where soils are deep and side slopes are not excessive (greater than 25%), few problems are likely to occur on well-designed and constructed trails.
3. Techniques of Trail Layout:
Conditions from level to steep will affect the way a trail route is determined. Side slopes of 0 - 5 % do not require side hill construction. Side slopes over 5% need side hill construction know as “trail grading” (see section 3.b.). General techniques for trail layout are as follows:
a. Level Terrain (non-graded trail sections):
b. Layout of trail on ascending or descending grade:
c. General guidelines for graded trail layout on side slopes.
Once the preliminary route has been marked, 1 or 2 additional trips should be made to finalize the route. Only when the route has final approval from the managing agency should trail construction begin.