Calculated Project Summary
Activity Duration and Critical Path
| Activity | Quantity | Productivity | Base days | Adjusted days | Schedule group |
|---|
Programme View
| Activity | Start day | End day | Duration | Programme bar |
|---|
Duration Scenarios
| Scenario | Working days | Calendar days | Weeks | Completion date |
|---|
Detailed Calculation Record
Saved Estimate History
| Saved | Length | Weeks | Cost | Completion | Action |
|---|
Formula Used
| Horizontal run per side | (Top width − Bottom width) ÷ 2 |
|---|---|
| Sloping side length | √(Depth² + Horizontal run²) |
| Excavation area | ((Top width + Bottom width) ÷ 2) × Depth |
| Pitching surface area | Drain length × (Bottom width + 2 × Sloping side length) |
| Pitching volume | Pitching surface area × Pitching thickness |
| Base duration | Quantity ÷ Daily productivity |
| Adjusted duration | Base duration ÷ Effective productivity × Allowances |
| Estimated weeks | Calendar days ÷ 7 |
How to Use
- Enter the drain length and cross-section dimensions.
- Select a linear, area, or activity productivity method.
- Set crew numbers, work fronts, machinery, and daily output.
- Choose activities and define schedule allowances or overlaps.
- Add material properties, wastage, and optional cost rates.
- Calculate, review warnings, and export the detailed record.
Example Data
| Example | Length | Top width | Bottom width | Depth | Pitching rate | Crews |
|---|---|---|---|---|---|---|
| Current project | 570 m | 1000 mm | 300 mm | 300 mm | 42 m²/day | 1 |
| Accelerated works | 570 m | 1000 mm | 300 mm | 300 mm | 55 m²/day | 2 |
| Manual works | 300 m | 900 mm | 200 mm | 350 mm | 24 m²/day | 1 |
Frequently Asked Questions
Does the calculator assume a true V shape?
No. You can select trapezoidal, true V-shaped, or rectangular geometry.
What do the two 300 mm values represent?
The default form treats them as depth and bottom width.
Can excavation and stone pitching overlap?
Yes. Choose concurrent activities, multiple fronts, or a custom overlap.
How are weather delays included?
Enter expected weather-loss days and a schedule contingency percentage.
Can I use more than one crew?
Yes. Crew count and work fronts directly affect productive duration.
Does the result include material quantities?
Yes. Stone, bedding, mortar, water, cement, fabric, and truckloads are estimated.
What is the PERT duration?
It combines optimistic, likely, and pessimistic estimates into one planning duration.
Are cost results suitable for tendering?
They are planning estimates. Confirm local rates, specifications, and contractual requirements.
Can I export the calculation?
Yes. Copy, CSV, PDF, and print controls appear after calculation.