Designing and Building Trails

People always ask me what’s involved in building trails. To begin with, it’s not as easy as it may seem. There is a process to building trails professionally. That process usually starts with a land owner or manager contacting our company about the idea of having a trail. They usually have a general idea of where they want the trail to start and key points of interest they would like to see along the way. It’s important to know the property boundaries of the project area as well as the general topography.

Another important factor is the funding for a project. Some projects are funded through recreational trail programs or through special use taxes in a community. Non-profit organizations are able to receive donations from individual donors to help a trail project come to fruition. The costs of building the trail can vary widely depending on the scope of work, but it isn’t unusual for most trails to run between $2-5 per foot. Exceptions would include downhill trails with lots of dirt work and ladder bridge features and trails through steep side slopes or where the trail is routed through heavy surface rock or bedrock. Some of the costs of construction can be reduced with partnerships with volunteer organizations which can provide labor for hand built trails or finishing behind machine built trails.

Trail Design

Once the property is determined and funding is acquired, the next step in the process is the design of the trail. This usually involves several site visits to determine any difficulties that need to be addressed during construction. This could include steepness of the terrain, how rocky it is, density of vegetation and type of vegetation. At this point, we will identify key points of interest and what type of user group will be using the trail. This will help determine the flow of the trail and the average grades the trail will maintain.

Next we start flagging the trail. We use a clinometer to help us accurately determine trail slope in percent grade. Most beginner trails are in a 0-3% grade, intermediate is 3-8%, and expert trails are greater than 8% average grade. The roughness of the trail surface also makes a huge difference in the difficulty of the trail.

Mountain bike trails usually require additional considerations. Trails can be built for directional use (i.e. uphill only or downhill only). Trails can be built as a flow trail or a natural feeling trail. A flow trail usually is machine built with most natural obstacles removed form the tread surface. It usually includes unsloped banked turns and switchbacks, rollers, step ups or downs, doubles, etc.. Natural trails will route trails over rock features and be more likely to include off-camber or root-covered surfaces that can not be avoided while staying on the trail.

Trail Construction

Trail construction is the next phase of the project. Professional trail builders use machines to help build trails in most building situations. This involves mini dozers and/or excavators. The size of the excavator is determined by the type of trail you’d like to build. Bigger machines are useful when moving a lot of dirt, like on a downhill trail with big table top jumps. Smaller machines allow you to build more cross country trails with more of a hand-built feel. Smaller machines can make a tread as narrow as 30 inches.

On machine built trails, we always finish with hand tools. This includes but not limited to chainsaws, loppers, axes, McClouds, rakes, etc. In rocky terrain we have used jackhammers, hammer drills, wedges, sledge hammers, chisels and more.

The flagging we used during the design phase is used as a general guideline for the construction if the trail. As we build the trail we allow, the trail to undulate along the flagged corridor to add interest and flow to the trail. We avoid straight lines and long sections of continuous grades.

As we need to we add grade reversals and dips to make sure any water that gets on the trail surface flow off as quickly as possible. Trails are normally out-sloped at 4-6% to allow the water that crosses the tread from above doesn’t turn and flow down the trail. Water is one of the most damaging forces of nature on trails. A poorly designed trail is very susceptible to erosion. Trails that follow the fall line (i.e straight down the hill) or trails that exceed 50% of the terrain cross-slope are likely to erode faster. This can be accelerated by differences in soil texture. Sandy soils have less cohesiveness than clay soils, so they are more likely to erode on steeper sections of trail. Some of these general rules can be broken if the trail includes natural or added rock along the tread surface.

Mountain bikers have also added wooden bridges or ladder bridges over uneven terrain or wetland areas. Wooden features are used to create a roller coaster like feel as well by including wall rides, banked turns, rollers, and jumps. Most trails cross streams or wetland areas at some point in the trail. In these areas we utilize bridges or create turnpike (i.e raised surface) trails. The possibilities of trail design and construction are only limited to the builders imagination.

Mapping and Trailheads

Once the construction is complete the trail needs to be mapped and the trail needs to be appropriately signed to allow users to safely navigate the trail or system of trails. Trailhead signs are useful in order to allow users to have a general understanding of the length and difficulty of the trails they are about to ride. Trail signage with difficulty level is useful for land mangers to help them manage risk by telling the users what type of experience they will have on a particular trail.

Designing and building trails is a multi-faceted and complex business and trade. It takes in consideration environmental and social factors in the design and construction of trails. Trails allow people to travel across landscapes on foot, bike, or vehicle than would be nearly impossible without there existence. They provide an outlet for our need for exploration, our need for physical activity, and a separation from a more industrialized world. Trails allow us to be more interconnected by providing corridors that allow us to easily transition from the human-built world and the nature that surrounds us.

Donald West is a Project Manager for Trail Ace Construction. Trail Ace Construction, a member of Professional Trailbuilders Association, was established in 1997 and is based out of White Bird, Idaho. You can find out more information about the company by calling Bonner Brumley at 385-228-5560 or find us at www.trail-ace.com.

For resources for learning how to build trails, check out “Lightly On The Land, The SCA Trail Building and Maintenance Manual” by The Student Conservation Association or “Trail Solutions, IMBA’s Guide to Building Sweet Singletrack.” You can also find more resources www.trailbuiders.org.