Editing Trail (section)

===Drainage===
{{More citations needed section|date=February 2021}}
[[Image:Waterbar.jpg|left|thumb|upright|alt=Photograph showing a waterbar drainage ditch to the left, the trail to the right |A [[waterbar]] in New York's [[Catskill Mountains]]. The trail forks right; the drainage ditch is to the left.]]
Trail construction requires proper drainage. If drainage is inadequate, three issues may occur: water may accumulate on flat terrain to the point that the trail becomes unusable; moving water can erode trails on slopes; or inadequate drainage may create local mud spots. Mountain bike trails slope out or across the trail 3–5% downhill to encourage water to run off the side, rather than down the trail bed.<ref name=DBST>{{Cite web |title=Designing and Building Sustainable Trails |url=https://imbacanada.com/designing-and-building-sustainable-trails/ |url-status=live |access-date=7 February 2021 |website=imbaccanada.com |archive-date=14 January 2021 |archive-url=https://web.archive.org/web/20210114114705/https://imbacanada.com/designing-and-building-sustainable-trails/ }}</ref>

To remedy the first problem, water accumulation on flat terrain, raised walkways are often built. They include turnpikes, causeways, embankments, stepping stones, and bridges (or deckwalks).<ref>{{Cite web |url=http://www.sctrails.net/trails/LIBRARY/TrailTerms.htm |title=Glossary of Trail and Greenway Terms |date=2008 |publisher=South Carolina State Trails Program |url-status=dead |archive-url=https://web.archive.org/web/20140413061637/http://www.sctrails.net/trails/library/trailterms.htm |archive-date=13 April 2014 |access-date=5 January 2014}}</ref> The earthen approaches are often done by cutting poles from the woods, staking parallel poles in place on the ground, then filling between them with whatever material is available to create the raised walkway. The more elaborate option of the deckwalk is by necessity reserved for shorter stretches in very high-traffic areas. Water accumulation is particularly common in the [[Northern England|North Country]] of England.

The second problem, water erosion, is caused because trails, by their nature, tend to become [[drainage]] channels and eventually gullies when the drainage is poorly controlled. Where a trail is near the top of a hill or ridge, this is usually a minor issue, but when it is farther down, it can become a very major one.

In areas of heavy water flow along a trail, a ditch is often dug on the uphill side of the trail with drainage points across the trail. The cross-drainage is also accomplished by means of culverts cleared on a semi-annual basis, or by means of cross-channels, often created by placing logs or timbers across the trail in a downhill direction, called "thank-you-marms", "deadmen", or '''[[waterbars]]'''. Timbers or rocks are also used for this purpose to create erosion barriers. Rock paving in the bottom of these channels and in the trailside ditches is sometimes used to maintain stability. The creation of water bars, with or without ditching, at major points of water flow on or along the trail, and in conjunction with existing drainage channels below the trail, is a technique that can be applied. Another technique that has been adopted is the construction of '''coweeta dips''', or drain dips, points on the trail where it falls briefly (for a meter or so) and then rises again. These provide positive drainage points that are almost never clogged by debris.
[[File:Black Hill (Peak District).jpg|thumb|alt= Photograph of a stone path laid across boggy ground |[[Black Hill (Peak District)]], Cheshire, England, where a stone path was laid across boggy ground]]
The third type of problem can occur both on bottomlands and on ridgetops and a variety of other spots. A local spot or short stretch of the trail may be chronically wet. If the trail is not directly on rock, then a mud pit forms.  Trail users go to the side of the trail to avoid the mud pit, and the trail becomes widened. A "corduroy" is a technique used when an area cannot be drained. This ranges from random sticks to split logs being laid across the path. Some early turnpikes in the United States were [[corduroy road]]s, and these can still be found in third-world forested areas. With recreational trails, it is common for the sticks to be one to three inches thick and laid in place, close together. Sometimes, a short bridge is used.<ref name=DBST/>