December 3, 2012

Trail Science 104: Stream crossings

Natural looking stream crossing

“Stream and river crossings present a challenge to trail managers who need to balance difficulty levels, safety, convenience, cost, environmental consequences, and aesthetics. Each kind of water crossing has consequences for the recreation experience and the lands being accessed.” – Trail Construction and Maintenance Notebook

A shallow stream ford is a crossing that will last for a long time with minimal maintenance and will provide a relatively low challenge to users. These crossings are best constructed at wider and shallower sections of a stream. The stream floor at the crossing is leveled so a knee-deep crossing is consistent. If water is shallower, rocks can be placed at intervals for stepping stones in the stream. Advantages of a shallow stream ford are they are low cost and are more challenging for the hiker than a dry crossing.
Trail stream crossing
With culverts, another form of a stream crossing, the trail’s tread extends over the culvert without interruption. Metal or plastic culverts are simpler ways to keep water flowing underneath a trail than a rock culvert. The rock culvert takes much more expertise to construct.
English: Culvert. A culvert where a stream run...
Culvert (Photo credit: Wikipedia)
Bridges cover a broad range of designs, from the simple to more costly suspended spans. Forest service bridges all require handrails unless it can be shown that the risk of falling off the bridge is minimal or the trail itself presents a higher risk. Log footbridges are one form of an elevated crossing. Bridges can be expensive, especially when materials must be delivered or packed into a site.
Single log bridge construction with handrail
Next: Trail Science 105 – Other trail elements

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