Feature Article - May/June 2003
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Trail Guide

Building multiuse trails and bridges

By Kyle Ryan


Design and construction

The successful trails Peter Webber of IMBA has been involved with typically are the ones with a "forward-looking" management staff and strong, well-organized volunteer groups. A supportive business community helps, too.

In general, though, there are 10 steps to planning and designing a sustainable trail, according to IMBA:

1. Get permission from the landowner and form a partnership. It goes without saying that you need to talk to whoever owns the land before constructing anything on it. Expect it to be a slow process and be willing to make concessions.

PHOTO COURTESY OF IMBA

Top 10 Trail-Building Mistakes

Defined by the International Mountain Biking Association

  1. Not getting landowner/land manager approval
  2. Creating excessively steep or graded trails
  3. Not maintaining a sustainable, accurate grade
  4. Going against the flow of a trail
  5. Creating trails with no outslope, which causes excessive erosion
  6. Having steep fall-line turns
  7. Using shoddy materials to build the trail
  8. Not spending enough time constructing a trail
  9. Using logs to line a trail, which can trap water and increase erosion
  10. Not repairing or closing damaged trails

2. Identify ownership boundaries. Locate your boundaries and get in touch with any landowners within those boundaries. Present them with a well-designed idea, which, IMBA says, can sometimes lead to access beyond what you originally intended.

3. Determine who will use the trail and what they will want to do. Walkers usually take short trips on trails. Equestrians will need a wide trail with high clearance and water stops. Disabled users will mostly need a wide trail with a hard-packed material and a gentle grade (5 percent). ATVs need an open, flowing trail and can handle rough areas. Mountain bikers will want anything from gentle, short trails to steep, difficult backcountry paths.

4. Familiarize yourself with the area. Study maps, aerial photographs, master plans, Geographic Information System (GIS) surveys, anything that's available. Identify the control points, that is, the places that determine where a trail will go.

5. Make loops. Trail systems with loops offer the most variety and can offer varying distances and degrees of difficulty, presenting trail users with a number of options.

6. Use a contour route. Planning gets a little more technical here. The contour route will connect the control points. Draw it using a topographical map, making notes of areas to avoid and areas to use. Avoid fall lines, which allow water to take a direct, concentrated route from the top of a hill to the bottom. (You want water to pass over the area in sheets, not streams, which cause erosion.) Keep the trail grade to 10 percent or less. Also figure out where you might need bridges.

7. Determine trail flow. IMBA identifies trail users by their means of travel, but their speed is important as well. For example, cyclists, runners and equestrians will travel faster than walkers.

A trail's tempo, or flow, comes in three varieties: open and flowing, tight and technical, and a hybrid of the two. Open and flowing trails are just as they sound: gentle. Wide with sweeping turns and long sight lines, they're good for beginning cyclists, equestrians and ATV users. Tight and technical trails have sharp turns and twists, which help minimize speed and reduce user conflict. Hybrid trails combine the two and are often good for urban areas.

8. Walk the trail corridor and mark it. Leave a trail of breadcrumbs to show where the trail will go by placing flags along its route. Be as comprehensive as possible.

9. Develop a construction plan. It takes a village to build trails and bridges. Trail users, land managers, volunteers/workers and landowners should all be involved in the planning.

10. Mark the exact trail location and get final clearance. Remark the trail after the construction plan has been finalized and double check that you have a green light to begin working.

The ideas all sound simple enough: You want to make a trail. So go in, clear out the area, make the trail and use it, right? Sort of. In these times of hyper-environmental awareness, there are a dizzying number of things to keep in mind, all of which boil down to one word: erosion.

When trail users, water and gravity combine, they can undermine the trail and negatively affect the surrounding environment. A number of organizations can help you design a sustainable trail.

Even though "mountain biking" is in its name, 98 percent of the trails IMBA's involved with are shared-use trails. The organization has the Subaru/IMBA Trail Care Crew, a free resource of two full-time professional teams that travel throughout the country to help promote trail use. Beyond that, there are the IMBA Trail Consultants, who help design multiuse trails. The RTC contributes its resources in rail-trail situations. The Internet, of course, has plenty of trail-design info as well.


Stacked Loop Trail Systems
Loops provide options. The majority of the system can be shared use, with a few areas designed for single use. Keep core loops near trailheads open and flowing to accommodate the widest variety of users. Outer loops can become progressively more technical and strenuous for people who want challenge.
  
Trail Flow
Open and Flowing
Tight and Technical
Poor Design (abrupt transitions from one type of design to another)
DIAGRAMS COURTESY OF IMBA