The following is from the "Wooden Portable Skidder Bridge
Information Sheet". This four part color brochure
is available by contacting:
of Forests, Parks and Recreation
103 South Main St., 10 South
Waterbury, VT 05671-0601
Using Portable Skidder Bridges for Temporary Stream Crossings
on Logging Operations:
- Avoid or minimize number of stream crossings.
- Locate crossing site where stream channel
is narrow for shortest possible clear span
and where stream banks are stable
and well defined.
- Crossings should be located where the stream
channel is straight with an unobstructed
flow of water.
- Avoid sections of stream where the stream
channel has a steep gradient.
Avoid steep approaches! The skid trail
approaching the stream should be
reasonably level for a distance of 50 feet on
Keep heavy equipment out of stream!
Use a skidder, excavator or bulldozer to
place the bridge over the stream.
Place at an adequate height above water
level (2-3 feet) so as not to obstruct
Where stream banks are “soft”, set
a log abutment to place the skidder bridge on. This
will minimize potential stream bank
Install bridge between “bumper trees” or
logs” to direct skidded logs across the bridge.
Stabilize the approaches with brush.
This helps to keep sediment off
the bridge deck and out of the stream.
Install waterbars on approaches
to the crossing. Install
25-50 feet away on each side to divert
water from the skid
trail into the buffer strip.
This will filter out sediment
preventing it from entering the stream.
Stabilize areas of exposed
soil within 25 feet of
a stream crossing by seeding and mulching
Portable skidder bridges are designed and intended for
use as temporary structures for crossing streams during a logging operation.
Upon completion of logging, these bridges must be removed.
- Remove panels by lifting rather than dragging across the stream channel.
- Re-shape stream bank if disturbed.
- Install deep waterbars on both approaches to divert any runoff from
the skid trail into the buffer strip.
- Seed and mulch all areas of exposed mineral soil a minimum of 25
feet from the stream or to the first waterbar.
- Keep bridge surface free of soil and logging
debris that could enter the stream.
any debris that enters the stream at the crossing location.
beams dry, the bolts will need to be tightened. Inspect monthly the
regularly to check for damage and deterioration.
on blocks and take precautions to minimize exposure to moisture. This
will extend the life of the bridge. A bridge
should last for a minimum of three years with average
use and proper care.
- Reusable. A wooden portable bridge should last for 3-5 years depending
on amount of use.
- Easy to install and remove.
- Can be manufactured from locally available
timber at a minimal cost.
- Less stream bank and stream bed disturbance.
- Minimizes soil erosion
- Keeps streams clear of debris
compared to poled fords or brushed-in crossings.
- Allows for fish passage.
- Avoids altering stream channel or restricting
flow of water.
- Are easy to transport, install and remove for re-use at multiple
- Are relatively easy to fabricate.
- Require little maintenance.
In conclusion, portable skidder bridges allow loggers
to harvest timber while following “Acceptable Management
Practices for Maintaining Water Quality on Logging Jobs in Vermont (AMPs).” They
reduce environmental impacts and costs associated with temporary stream
crossings. The initial cost for these bridges is an investment that
will pay for itself. Clearly, these bridges can be a cost-effective
way to protect the environment while improving operational efficiency.
An Agency of Natural Resources (ANR) permit
is not required for installing portable skidder
bridges except under the following conditions:
- Located at a point on a stream where the drainage area is greater
than one square mile and the structure does not
maintain the existing streambed material and elevation.
- Located on a stream where the drainage area
is greater than one square mile and the structure
will not be removed at
the time of completion of the current timber
- Not consistent with the AMPs.
If any of these three conditions cannot be met, the stream crossing
will require prior approval by a Stream Alteration Engineer, Vermont
Department of Environmental Conservation (DEC). Please contact one of
these district offices for assistance:
Rutland: (802) 786-5906
Essex Junction: (802) 879-5631
Barre: (802) 476-2679
DEC Web Site: http://www.anr.state.vt.us/dec/waterq/rivers/htm/rv_contact.htm
The Department of Forests, Parks and Recreation
(FP&R) provides technical assistance for forest landowners and
loggers. Please contact one of these district
offices for AMP assistance:
Springfield District Office: (802) 885-8855
Rutland District Office: (802) 786-0060
Essex Junction District Office: (802) 879-6565
Barre District Office: (802) 476-0170
Saint Johnsbury District Office: (802) 751-0110
Headquarters office: (802) 241-3678.
FP&R Web Site: http://www.vtfpr.org/resource/for_forres_ampfor.cfm
This document is available upon request in large
print, Braille, and audio cassette. VT TDD 1-800-253-0191