Overview, Synopsis, Who is WORBA, Why Blue Mound, Building Trail, Trail design, Proposed trails , Proposed map, Crews, Volunteering, Work log
Overview, Synopsis, Who is WORBA, Why Blue Mound, Building Trail, Trail design, Proposed trails , Proposed map, Crews, Volunteering, Work log
WORBA looks at designing natural surface trails that require minimal maintenance, and therefore needs to avoid major erosion problems. Preventing trails from rutting and eroding involves knowing what's causing the damage, and on Wisconsin trails, that means knowing water and it's habits. Water normally originates from rain or snowmelt run-off. The water soaks into the soil as best it can, and then the excess flows across the surface where gravity pulls. Now we put a trail in the path. If the trail is parallel to the pull of gravity, or is the path of least resistance, water will run down the trail. Fall line trails like this channel water, allowing it to pick up speed, which allows it to carry more silt, dirt, pebbles or rocks. Anywhere the water is running fast - even just during the snowmelt runoff season - the trail may have erosion problems. If instead of running the trail parallel to gravity, we put it perpendicular, or across the side-slope of a hill, the water crosses the trail. By making this contour trail slightly outsloped, we make sure the water has an unobstructed flow path - nothing channels it, so it passes over the trail without speed, and doesn't pick up soil and move it at all. Waterbars both channel water and require periodic cleaning, so we don't recommend their use as a water control device. If we need to run a trail uphill, we use methods other then fall line construction, such as a gradually rising cross-slope trail, with dips that force any water travelling on the trail off the side. If we need to travel uphill on a limited horizontal surface, we tack back and forth on the side slope, turning in switchbacks if the slope is steep.Water has a better chance at picking up soil where user impact has caused soil loosening - for hikers, this would be places where the trail is so steep they dig their boot lugs in, for bikes, this would be places where users had a speed change and skidded their wheels. By knowing the habits of the users and designing the trail so speed-change is gradual, skidding is prevented and impact is minimal.
Trail flow affects trail sustainability, user safety, and type of use of a trail. The flow of a trail describes its pattern: either tight & technical or open & flowing. A tight and technical section of trail is typified by smaller radius turns, trail features such as log crossings, rocky terrain, close-in trees, or other obstacles that the rider can test their skill on. Tight and technical trails are traveled at low speeds, and challenge the balance and bike handling skills of the user. Open and flowing trails, by contrast, only have gradual turns, straight-aways, few obstacles and clear lines of sight. Some riders travel as fast as they can, getting the challenge of speed and aerobic ability. Others, like novices, feel comfortable on these trails because of the line of sight is so great, and they get the same challenge at a lower speed. As they become more skilled or more fit, their speed increases on these trails, or they look towards the challenge of the tight and technical sections. These trail types offer different challenges for the recreationalist, and can be parts of the same trail. However, there should be long sections of each, with the transition between well thought out, lest a rider traveling at 15 mph have to lay on the brakes and skid to make a sudden 90 degree corner. The skidding may cause an erosion problem, the reason for the corner may be a safety problem, and the sudden transition may detract from the trail enjoyment. A better transition may involve the trail beginning to snake left and right, gradually making the weaving more pronounced, and passing between two large boulders to cause the rider to slow down to an appropriate speed before they get to the 90 degree corner. And most cyclists won't even notice they did it.
Off-road cycling trails can be and have been created in a variety of soil types. The best soil type for sustainability is rock, such as the petrified sandstone in Moab, Utah, known as Slickrock. On the Olympic Mountain Bike course in Atlanta, GA, large slabs of granite are parts of the trail. "Armoring" a section of trail with flat rocks wedged together and packed in to prevent movement remains a popular way of hardening a section often subjected to large water volumes (the apex of a ravine or a stream crossing). Next in line for sustainability is a soil with a high clay content. The clay acts as a binder for the soil and keeps the rest of the soil from moving. After trail users compact the soil, the trail is often called "hardpack" and is very resistant to erosion. This trail surface has low rolling resistance on tires and makes the trail visible when compared to the uncompacted areas around it. A little lower in the list of sustainability is a soil with a high sand content. While the sand has the benefits of draining fast - sandy soil is the first to dry after a rainstorm - it doesn't compact very well and the "loose" soil isn't easy to hike or bike in - so users tend to go around the soft section and begin to break down the sandy soil on the sides, causing trail widening. Sand mixed with clay holds better, but a trail can be made on sandy soil as long as the limits of fall line construction and user impacts are lessened to allow the soil to hold together. Gravel is a sustainable substance, but unless bonded to the soil, tends to wash away on any slope, and the possibility of a fall in gravel makes some riders skittish - road rash hurts!
Multiuse trails on public property are often built with skate-skiing in mind, and are 8 feet wide and grassy because of it. For trails designed with off-road bicycling in mind, a snow-shoeing and hiking partnership may be better. Off-road cycling will remove vegetation from the trail tread, and we often start the tread by removing the soil that is permeated with small plant roots. If we did this on an 8 foot wide trail, we'd likely have an erosion problem no matter how hard we tried. A smaller trail tread is not so much a problem. When thinking of a person walking through the woods, their feet may touch down anywhere beneath their shoulders, about 2 feet in width, or 3 feet if the person has snowshoes on. To make them more comfortable, the brush can be removed on either side to give elbow room. On an off-road bicycle, the same elbow room applies, but the only part touching the ground is the 2-inch wide tire. Granted, you want more tread width then 2 inches, but 2 feet is plenty for singletrack. WORBA consistently brushes back smaller vegetation 4 feet on either side of the centerline of the trail, but mostly so that it takes longer for the vegetation to need brushing again - low maintenance is the name of the game. The trail surface should be natural wherever possible. Bridging and boardwalks being the exception in wet areas, the natural soil is often the best for the conditions at the location of the trail - otherwise that soil would have washed away in a storm 1000 years ago. If the impact of use is going to change the conditions the soil is suited for (highly sandy soil doesn't take impact well, for example), an additive may be mixed into the soil (clay or bentinite for our example), the trail may be raised with a boardwalk, or the trail may be routed around the trouble spot.
Why do people ride off-road? Most pavement has fast cars on it, and many wish to avoid the traffic. The linear State Trails like Military Ridge offer an alternative, but these trails are wide, consistently surfaced, and only go where railroads could - shallow hills and gradual corners, and often right next to highways. People ride off road because they like the variety, the challenge, and the natural setting. Allowing for what's available in a given area, a single trail may have long hill climbs and roller-coaster descents, flat straight-aways, snaking path, tight corners, rocky, sandy, and hard-packed surface, a water crossing, a bridge, a fence with a stile-crossing, log piles, a great view, a bog crossing, a prairie full of giant blue-stem, a grove of birch trees, savannah oak, three types of pine tree, a patch of Indian paintbrush, a patch of milkweed, an old stone wall, canyons, ridges, caves, rusting old farm equipment, an alfalfa field, gullies, boulders, kettles, mounds, overhangs, cliff-side exposure, hummocks, dells, waterfalls, sinkholes, or seasonal creeks - pick at least ten of the above, or more. The trail should not be too easy, should take the users right up to the trees and boulders and prairie flowers that they can touch, and should be long enough to have a variety of skills needed. Above all, they should be fun.
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