| Scenario | Length (m) | b (m) | d (m) | z (H:V) | Excavation (m³/day) | Lining (m³/day) | Workdays/week | Estimated calendar days |
|---|---|---|---|---|---|---|---|---|
| Village distributary | 500 | 2.0 | 1.2 | 1.0 | 180 | 40 | 6 | ~22 |
| Farm irrigation lateral | 250 | 1.2 | 0.9 | 1.5 | 120 | — | 6 | ~9 |
| Industrial supply canal | 1200 | 3.0 | 1.5 | 1.0 | 260 | 70 | 7 | ~28 |
- Select Detailed when you know canal dimensions and side slope.
- Enter length, bottom width, depth, and slope to compute quantities.
- Add productivity per crew, number of crews, work hours, and efficiency.
- Enable lining if applicable, then set thickness and overlap start %.
- Add mobilization, contingency, and delay factor for realistic plans.
- Press Calculate Duration and download the report if needed.
Scope and sequencing for canal works
This calculator converts measured quantities into a practical schedule by combining excavation, optional lining, and planned non‑productive time. Use it early to frame the programme, and again during execution to test recovery actions. Use the start date to communicate targets across teams. It is intended for earthworks and lining packages; add separate allowances for structures such as culverts, head regulators, crossings, and major dewatering.
Productivity inputs that control duration
Productivity is entered per crew for an 8‑hour day, then scaled by work hours and an efficiency factor. For example, 180 m³/day/crew becomes 229 m³/day/crew at 10 hours with 85% efficiency. If access and hauling are adequate, increasing crews typically reduces phase time nearly in proportion. When haul distance or disposal becomes limiting, keep crews realistic and capture uncertainty with the delay factor. Track actual output daily and update inputs for better forecasts each week.
Excavation quantity drivers from channel geometry
For trapezoidal channels the excavation area is driven by bottom width, depth, and side slope. A 2.0 m bottom width, 1.2 m depth, and 1H:1V slope yields 3.84 m² of section area. Over 500 m, that is about 1,920 m³ of excavation. Small geometric changes matter: steeper depth or flatter side slopes increase both volume and trimming effort, so confirm dimensions against the latest drawings.
Lining phase overlap and finish risk
When lining is enabled, the calculator estimates lining volume from wetted perimeter, thickness, and length. It also supports overlap by starting lining after a chosen percentage of excavation is complete, reflecting crews working behind the excavation front. For an 80 mm lining, volume rises quickly on long reaches, so lining productivity can become the critical path and determine the finish date.
Using scenarios to reduce schedule uncertainty
Add mobilization and contingency days for surveys, staking, access preparation, inspections, and minor stoppages. Then apply a delay factor to represent weather, approvals, and material delivery risk. Switching from 6 to 7 workdays per week reduces calendar days by about 14% for the same working duration. Export CSV for estimating and PDF for reporting.
FAQs
1) Which mode should I choose?
Choose Detailed when you know canal geometry. Choose Single production rate when you already have a total quantity or need a fast, high-level schedule check.
2) What does the efficiency factor represent?
It scales production to realistic output, accounting for breaks, travel, minor rework, congestion, and site constraints. Use observed site performance when possible.
3) How are calendar days calculated?
Calendar days are derived from working days using your workdays-per-week selection: calendar = working × (7 ÷ workdays/week). This reflects rest days without changing production assumptions.
4) Can lining start before excavation finishes?
Yes. Set a lining start percentage to model staggered crews. The calculator then compares excavation completion with lining completion to find the true finish.
5) Why add mobilization and contingency days?
Some tasks are time-based, not quantity-based, such as surveys, setting out, access preparation, inspections, and minor stoppages. Fixed days make the plan more realistic.
6) What if my result looks too optimistic?
Lower the efficiency factor or increase the delay percentage, then validate productivity and crews. Also consider haul distance, groundwater control, and spoil disposal capacity.