Forestry Road Engineering and Production Analysis Standards

Road Curve Geometry and Calculations

Note: D is not Delta (Δ).

(Culverts used in road construction should be at least 15 inches in diameter.)

Determining Degree of Curve (D)

When choosing D, round the result to the closest number divisible by 4.

• D = External (E) of a one-degree curve / Desired E
• D = Tangent (T) of a one-degree curve / Desired T
• D = 100 * Delta (Δ) / Desired Length (L)
• D = (Radius * Degree) / R

Curve Formulas

• Radius (R): R = 5729.65 / D
• Tangent (T): T = (T of 1 degree curve, using Δ) / D
• External (E): E = (External, using Δ) / D
• Length (L): L = (100 * Δ) / D
• Long Chord (LC): LC = 2R * sin(Δ / 2)

Stationing and Layout

• PC Station: PI - T

  *Nomenclature Example: 6+55.55 should be expressed as 655.55*

• PT Station: PC + L
• Deflection Angle: Deflection Angle = D / 4
• Tangent Distance (TD): TD = sin(2 * Deflection Angle) * R
• Tangent Offset (TO): TO = (1 - cos(2 * Deflection Angle)) * R

Long Chord Bearing Calculation

If the bearing is a foresight, the LC Bearing is the same as the PC Bearing.

If the bearing is a backsight, flip the PC bearing and subtract (Δ / 2) to the closest 90 degrees (which would be North and South for bearings).

Logistics and Delivery Tracking

Information to be collected for tracking loads and deliveries:

• Date of delivery
• Tract identification
• Person delivering load
• Product type
• Destination
• Time in and out
• Weight in and out
• Deductions

Analyzing Production Efficiency

Common Causes for Lost Production

Lost production can result from various factors:

• Market conditions
• Weather
• Mechanical failures
• Labor issues
• Moving operations
• Planning deficiencies
• Regulations
• Tract conditions
• Other unforeseen issues

Time Study Methodologies

Gross Time Studies

Uses Standard Man Hours (SMH), typically measured on a daily or weekly basis for production.

Work/Activity Sampling

Good for bidding new timber tracts. Activities are divided into discrete, measurable units. This method is more detailed than gross studies but cheaper than elemental studies. However, it cannot demonstrate direct cause and effect.

Elemental Time Studies

Requires precise measurement tools such as a stopwatch, camera, etc., to capture detailed work elements.

Preventing Timber Theft

• Load tracking systems
• Cruising the forest beforehand (inventory)
• License plate capture
• Physical presence/Security monitoring

Forest Road Design and Construction

Four Basic Road Cross Sections

• Cut-and-fill: Used on gentle slopes (less than 50%).
• Full-bench: Used on steep slopes (greater than 50%).
• Through-cut: Used to prevent excessive grade or on high-traffic roads.
• Through-fill: Used in flat terrain or wetlands.

Four Basic Road Shapes

Outsloped Roads

The cheapest option, requiring less excavation and no ditches. May require seasonal closures and can be dangerous if slippery. Use when the grade is gentle (less than 8%), traffic is low, and rutting can be controlled.

Insloped Roads

The road slopes inward toward the uphill side of the terrain into a ditch. Water usually drains out using a cross-drain culvert or broad-based ditch. Used when the road grade is steep or when ice, snow, or slippery conditions are expected.

Crowned Roads

The highest point is in the middle, allowing water to drain to ditches on both sides. Water is moved to the downhill ditch with cross-drain culverts. Used when a two-lane road is needed, a single-lane road is on very steep terrain, the road grade is flat, or in slippery/icy conditions. Requires regular maintenance of ditches.

No Shape Roads

Some forest roads, particularly on small private ownership lands, have no defined shape. These roads will hold water, rut, experience subgrade failure, and create environmental damage.