10 MOST COMMON TRAILBUILDING MISTAKES

For as long as humans have been following trails, we've been making mistakes on trails. At least our missteps—whether they left us in the digestive tracts of saber-toothed beasts or just badly banged up—usually affect only ourselves. But when trailbuilders make mistakes, they affect everybody. Trail users, land managers, vegetation and wildlife all feel the sting of the well-meaning but inexperienced trailbuilder. In our travels, we often see the same mistakes made again and again, but the good news is they can all be avoided. Here, we bring you the top 10:
1. Not Getting Land Manager Approval
We know, we know: you just want to build trails. But believe us when we tell you that nothing—not a single darned thing—is more important before starting trailwork than the approval of the land owner or manager. In our experience, failure to secure permission is the single biggest cause of trail closures. When it comes to building trails, to ask for forgiveness is not better than to ask for permission. And anyway, why would you want your hard work to risk immediate destruction if your rogue trail is discovered and torn down or ripped up? Illegal trail building also does serious damage to the public reputation of mountain bikers and can make it even harder to get legal trails approved and constructed. 
2. Falling for the Fall Line
Put simply, fall-line trails are erosion nightmares. They turbo-charge natural and user-created erosion, and generally live short lives before becoming loose, wide, ecosystem-damaging disasters. To build trails that last, use both the "Half Rule:" Trail grade, or steepness, shouldn't exceed half the grade, or steepness, of the hillside; and the "10 Percent Rule:" Overall trail grade should be 10 percent or less. While that might not sound like much, it's much steeper than you think.
3. Guessing the Grade
Nobody, no matter how masterful their eye, can guess trail grades right every time. Trust us, we know. Use a clinometer to confirm the grade whenever you're laying out trail—it's worth a regiment of self-powered, Fantasia-style Pulaskis, because no amount of physical labor can fix a trail built on an unsustainable grade. If you don't have a clinometer, we highly recommend an investment in this indispensable tool.
4. Going Against the Flow
Not even race courses, which are sometimes designed with erratic flow to throw off a racer's rhythm, should make this trailbuilding faux pas. All trailbuilders should make smooth transitions their mantra. Bad flow, especially fast sections leading into sharp, blind turns, is a primary cause of user conflict. When you are building, think flow—it's the key to an enjoyable trail. And it doesn't need to mean a smooth, easy trail. A trail with flow is a smart trail: one with good transitions that doesn't regularly catch you off guard or rudely interrupt your rhythm.
5. Half-Bench is Half-Baked
The only time you should ever skimp on a fully bench-cut trail is, (1) when the sideslope is so steep—80 percent or greater—that the backslope exceeds six feet in height or, (2) when your trail design forces you to build close to the downhill side of a large tree. In both cases, a proper "crib wall" should be built to support your partial bench and, as in all trails, the tread should maintain a five- to seven-percent outslope. Not sure what any of this means? Pick up our widely-regarded book, Trail Solutions, to learn the basics of trail building.
6. The "West Virginia Climbing Turn"
Our friends in West Virginia affectionately gave this name to some of their steep, fall-line turns. While they've gotten away with it in a few locations because of the soil and user types, most fall-line turns will erode badly and quickly. If you want your climbing turns to endure, build them on sideslopes with no steeper than a seven- to 10-percent grade. In general, make sure your turns fit your trail flow, landscape and are built sustainably. Giant rollers aren't good transitions into and out of a tight, high-alpine switchback, whereas 8-foot-tall berms on the mellow, multi-use trail in your local park probably aren't appropriate.
7. Building Houses of Straw
Remember the little piggy who built his house with straw? He was eaten by a wolf. Using shoddy materials when building trail structures leaves you and others similarly vulnerable to all kinds of trouble that stem from weathering and insufficient construction. This opens the door to things like pain, guilt and even big, bad lawyers. For publically accessible, multi-user trails trails it's a often a better bet to build with rock and dirt and avoid wooden structures altogether.
8. Finishing a Line Before Its Time
We heartily support on-the-trail training, but some new trailbuilders are so eager to keep building more! new! better! trails that they don't devote enough time or care to each new trail section. Resist the temptation to move forward. Don't finish a line before its time, and always fix past mistakes.
9. Building a Pathway to Grandma's House
This is what we call some trailbuilders' obsession with lining trail with logs. A properly constructed trail shouldn't need them. In fact, lining a trail with logs can trap water and increase erosion.
10. Ignoring Old Wounds
As mountain bikers, we may think our scars are cool, but scars on the land left by closed trails are damaging wounds that need to heal. Always reclaim eroded areas with natural obstacles—like logs or rocks that divert the flow of water and soil—and reclaim all closed trails with transplanted native vegetation that conceals the old corridor (so people don't try to keep riding it). The old trail should be invisible to the untrained eye so as not to be tempting; a fence or a sign isn't going to cut it if a trail is visible beyond. Shine the spotlight on the great, new trails you've built, not the ugly scars that have been left behind.

Thank IMBA for the great article