FOPR 2 Forest Access and Transportation Flashcards
Define Forest Operation
Activities associated with timber harvesting. These include planning, supervision, record keeping.
What are the components of a forest Operation? (4)
- Planning phase: converting information and data into action.
- Development phase: constructing roads and other transport systems.
- Harvesting Phase: Falling, processing, skidding/yarding, hauling, road maintenance, Dumping.
- Forest Management Phase: planting, silviculture, etc post harvest.
What are some physical features of a road? (8)
- Sub Grade material
- Surface material
- Ditches
- Culverts
- Bridges
- Ballasts
- Saftey and access controls
- Special design features
What are some design features of a road? (9)
- Horizontal alignment
- Vertical alignment.
- Tangent.
- Horizontal Curves
- Vertical Curves
- Switchbacks.
- Cut’s and Fills.
- Drainage Location.
- Drainage specification.
Describe the levels of survey accuracy
Level 1 - done where there is a low likelihood of landslides, or where geometric road designs are not required.. Accuracy 1:100
Level 2 - done on stable terrain with a low likelihood of landslides but where geometric road designs are desired. Accuracy 1:300
Level 3 - done on areas of moderate to high likelihoods of landslides and geometric road designs required. Accuracy 1:1,000.
Level 4 - high order survey for placement of permanent bridges etc. Accuracy 1:5,000
What is the purpose of the recce process?
To collect relevant stand information, and to find the best road location through a series of control points (good and bad)
Why might the lowest cost road not be the best road?
The lowest cost road could also be in conflict with a management objective, such as disturbing sensitive soils to avoid an extensive side cut.
Through this initial Recce process, what features are being identified?
Road control points (stream xing, poc/pot, landings, switch locations, gravel sources)
Topographical features
Timber characteristics,
Stream assessments
Why are circular curves problematic for high speed paved roads? Why are circular curves considered acceptable for most forest service roads
Circular curves don’t allow for spiral transition from straight to a constant radius when entering and exiting a curve. this causes a vehicle to move left or right of the intended course of travel.
Forest roads are lower speeds, which reduce the previously described movements. also the earth roads gradually change to match traffic as they are travelled.
Why is Vertical curve design important
If the roads change grade too quickly, logging trucks can become airborne on a crest or bottom on the springs in a dip.
sudden changes in grade can also cause binding between tractor and trialer units.
How does water affect roads?
Weakens internal structure and causes erosion externally
3 Environmental impacts of roads (water related)
Surface erosion: occurs when mineral soil is dislodged and transported by water
Mass Wasting: large volume of soil in a single event
Sedimentation
What Structures or design features are used to manage water?
Crown: road surface drainage to prevent water penetration, surface erosion, or puddles.
Ditch: Intercepts surface water, grown water flow, subgrade drainage, and catches debris.
XD structures: culverts and bridges allow accumulated water to discharge out of a ditch, or maintains existing watercourses.
How are Crossing’s designed
Site is selected
flood conditions assessed
determine the size of crossing
assess fish passage requirements.
Bridge Approaches should have straight and level approaches to avoid the hazards of:
- Unplanned foreces applied to he bridge
- Vehicles having control problems
- Trailers not tracking straight onto the deck
- Gravel and water accumulating on the deck
Types of Culverts and their advantages
- Corrugated metal - easy install, easy to find, but are heavy and much be mechanically placed
- corrugated plastic- lighter than metal - easy to install and transport.
- Concrete - labor intensive but have low resistance to waterflow and are durable.
- wooden box culvert - offers a natural bottom, built with on site materials, easily repaired, but are labor intensive.
Components of a bridge
- Opening: must be tall enough to allow for debris clearance during flood.
- Sub Structure fills space between the foundation and superstructure. (log crib or rip rap)
- Superstructure: includes beams, deck, and rails.
- Deck : Wood vs concrete depends on unique site and use conditions
Road Planning and Implementation
Planning refers to the initial information and conditions. road standard used geology or slope stability, survey work appropriate.
Timing: best to build roads when soil moistures is at lowest. or at least stop construction during wet periods.
Mitigative Preparation: be able to respond to planned and unplanned conditions or events.
Road Construction phases
- R/W Clearing: trees are removed 20m width
- Stripping: unsuitable organic material is removed and disposed of.
- Sub grade construction: excavator or bulldozer places the cuts and fills of the road create the prism.
- Drilling and Blasting: any rock excavation on the subgrade will require drilling and blasting.
- Drainage Structures
- Ballasting and surfacing: if subgrade material doesn’t have suffiecnt strength, ballasting is required to strengthen cut/fill material.
- Stabalization: if erosion is created, special control measures must me made.
Road Maintenance Activities
Grading (shaping crown, pulls material back to surface)
Surface repairs (pot holes)
Re-surfacing
Inspections of surface conditiosn, xd’s settling, tension cracks, stability issues.
ditch/culvert maintenance
snap removal
veg control (brushing)
Road Deactivation
Reshaping the road to remove sections of high risk to damange (water or stability related)
Types of Deactivation
Seasonal Deactivation: if road will be used again within a year. xd and WB
Semi-Perminant Deactivation: if road will be inactive for several years. restores natural stream channels and xd’s down grades from stream xings.
Permenant deac: same as semi but adds removal of all structures and pull bak of fills with stability risk.
Road Standards
list of specifications for geometric design and construction of a road. Standards vary because of variations in required use.
The question “ What is the purpose of the road?” will serve to evaluate the benefits of different standards.
Spec Types
- Physical conditions (cut and fill slope angles, ballast and surface material
- Environmental (water mgmgt, slope stability, site loss)
- Use/traffic (road class/speed design)
