| Scenario | Footprint | Density | Slope | Method | Crew | Buffered Area (m²) | Duration (days) |
|---|---|---|---|---|---|---|---|
| Small pad prep | 5,000 m² + 2 m buffer | Medium | 8% | Brush cutter | 4 | 5,408 | ~1.4 |
| ROW clearing | 200 m × 10 m + 1 m buffer | Heavy | 12% | Excavator | 3 | 2,640 | ~0.6 |
| Dense overgrowth | 8,000 m² + 3 m buffer | Extreme | 25% | Mulcher | 2 | 9,486 | ~1.1 |
The calculator estimates area to clear, adjusts productivity using site factors, then converts production to time and cost.
- Buffered Area: Abuf = (L + 2b)(W + 2b) for dimensions, or Abuf = (√A + 2b)² for area mode.
- Factor Total: F = Fdensity × Fslope × Fheight × Fdisposal.
- Crew Productivity: Pcrew = Pbase × crew, Peff = Pcrew / F.
- Time: hours = Abuf / Peff, days = hours / hoursPerDay.
- Biomass Volume (rough): V ≈ Abuf × height × (cover/100) × 0.25.
- Cost: labour = manHours × rate, equipment = crewHours × units × rate, disposal = V × unitCost, total = direct × (1 + markup%).
- Choose Site Area or Length × Width.
- Add a buffer if you need access or safety clearance.
- Select density, slope, and height that match field conditions.
- Pick the primary method and optionally enter a custom productivity.
- Set crew size, working hours, and the cost rates you use.
- Click Calculate. Review results above the form.
- Use Download CSV/PDF to save the estimate.
- Survey hidden hazards (stumps, rocks, utilities) before clearing.
- Apply permits and environmental constraints to your plan.
- Use higher contingency for unknown ground and dense growth.
- Re-check disposal constraints, haul distance, and site access.
Clearance Scope and Buffering
Vegetation clearance planning starts with defining the footprint that will actually be worked. This calculator supports direct area input or length-by-width geometry, then expands the footprint with a buffer. Buffering is useful for access lanes, equipment swing, safety offsets, and edge trimming. As buffer grows, time and cost rise nonlinearly when dimensions are used.
Productivity Drivers and Adjustment Factors
Production is modeled as a base productivity per worker and method, multiplied by crew size, then reduced by site factors. Density, slope, average height, and debris handling increase the factor total and reduce effective output. Use a custom productivity value when you have verified crew history, measured trial strips, or contract benchmarks.
Labour and Equipment Cost Structure
Direct cost combines labour, equipment, and optional disposal pricing. Labour uses total man-hours (crew hours × crew size), while equipment uses crew hours × equipment units. Overhead and contingency are applied as markups to cover supervision, mobilization, unknown obstacles, and productivity risk. Keep rates consistent with your contract unit basis.
Debris and Disposal Planning Metrics
Debris volume is estimated for planning using buffered area, height, and ground cover. It helps size haul trucks, stockpile zones, chipper capacity, and disposal budgets. Haul-off generally slows production due to loading cycles, traffic management, and tipping time. Onsite chipping can be faster but may require additional spread or finish passes.
Interpreting Results for Bid and Schedule Control
Use the KPI tiles to validate feasibility: buffered area, effective productivity, crew hours, duration, and total cost. If the work difficulty is high, consider increasing crew size, switching methods, reducing buffer, or staging disposal. Recalculate for “best case” and “worst case” to set contingency and communication thresholds.
| Area (m²) | Buffer (m) | Density | Slope (%) | Method | Crew | Effective Prod. (m²/hr) | Duration (days) |
|---|---|---|---|---|---|---|---|
| 5,000 | 2 | Medium | 8 | Brush cutter | 4 | ~436 | ~1.4 |
| 8,000 | 3 | Extreme | 25 | Mulcher | 2 | ~860 | ~1.1 |
FAQs
1) What should I use for the buffer?
Use the smallest buffer that still supports access, safety, and trimming. Common planning buffers range from 0.5–3 m, but utilities, fencing, or protected zones may require more.
2) Why does slope reduce productivity?
Slopes slow walking, cutting, machine positioning, and debris handling. They also increase fatigue and safety constraints, which lowers effective work time and steady output.
3) When should I enter custom productivity?
Enter custom productivity when you have measured site trials, historic crew production, or contract standards. This improves accuracy more than any single factor selection.
4) How are crew hours different from man-hours?
Crew hours represent the clock time the crew works. Man-hours equal crew hours multiplied by crew size and are used for labour cost estimation.
5) Is the biomass volume exact?
No. It is a planning estimate using area, height, and cover. Validate with field observation, species type, moisture, and the chosen handling method.
6) How do I price disposal?
Use a unit cost per cubic meter for hauling, tipping fees, or processing. If you chip onsite and spread, disposal cost can be zero but equipment time may increase.
7) What if my estimate feels too optimistic?
Increase density or height, switch disposal to haul-off, and add contingency. Also reduce base productivity unless you have proven rates for similar conditions.