Cost Analysis and Drainage Options for Road Construction
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Total Costs/SMH = (Fixed Costs) + (Variable Costs * UT%) + (Labor Cost)
Fixed Costs = (Depreciation) + II&T
Depreciation = ((Purchase Price) - (Purchase Price*Salvage Value%)) / (Useful Life*SMH/year)
II&T = (II&T% * AVI) / (SMH/year)
M&R = (M&R% * Depreciation)/(Utilization %) F&L = (Fuel Consumption * Fuel Price)(1 + Lube %)
Labor Costs = Wage rate(1 + Overhead & Fringe%)
Productivity (tons/SMH) = tons/pmh * Utilization%
Harvesting cost ($/ton) = (Total Costs/SMH) / (Productivity)
Break Even Production Level (BEP) = (Fixed Costs/day) / (Selling Price/ton - Variable Costs/ton)
FC/day = (Total FC/year) / (Working Days/year)
VC/ton = (Total VC) / (Total Tons)
Culvert Diameter...
C = 1 for impervious, .7-.8 steep slopes moderate runoff, .5-.6 moderate slopes dense cover, .3-.4 gently rolling ag land, .2 for flat highly pervious soils
Cross-sectional area of pipe required in ft2 (A) = (Runoff Coefficient (C) * (Watershed Acres (M))0.75
D = SQRT(A/.005454) *always round UP to the nearest even numbers.*
Volume of Gravel ft3 = (Miles of Road) (5280 ft/mi) (Width of Road Feet)(Gravel Surface Inches / 12 in/foot)
Tons of Gravel = (Volume of Gravel ft3 * Gravel Weight lbs/ft3) / (2000 lbs/ton)
Cost = Tons of Gravel * $/ton
Drainage Options... Water Bars: Best for Closed Roads and Skid Trails
- Not designed to be driven over
- Minimal maintenance if constructed properly
- Easy to install with bulldozer
- Can't drive over or else will damage it
Broad-based Dips: Permanent Roads with Skid Trails
- Can be used with or without ditches
- Not effective when road grade > 10%
- Gravel often necessary on high volume roads
- Must maintain dip - easily lost due to traffic and sloppy grading
- Longer approaches and flatter slope for low-clearance vehicles and/or high travel speeds
Rolling Dips: Carry Water from Inside to Outside of Roads
- Gently sloping roads
- Light to moderate traffic
- Difficult to construct properly
- Should be designed with vehicle clearance and wheelbase
Water Turnouts/Diversion Ditches: Permanent Roads, Temporary Roads, and Skid Trails
- Used to divert water from road to skid trail
- Diversion ditch should always go downhill
- Locate water turnout away from streams and wetlands
- Should trap sediment at end of turnout
Cross Drain Culverts: Divert Water from Uphill Side of Road to Downhill Side
- Often used with insloped roads
- Better than rolling dips or broad-based dips when traffic volume is high
- Culverts require maintenance to prevent clogging