| Parameter | Example value | Notes |
|---|---|---|
| Total volume (bank) | 12,000 m³ | Measured from survey quantities. |
| Swell factor | 25% | Loose volume increases after excavation. |
| Truck capacity (loose) | 14 m³ | Heaped/struck as used on site. |
| Fill factor | 95% | Accounts for imperfect fills. |
| Distance one-way | 6.5 km | From load point to dump point. |
| Speeds loaded / empty | 28 / 36 km/h | Average effective speeds. |
| Load / dump / delay | 3.5 / 1.5 / 2.0 min | Fixed times per cycle. |
| Shift plan | 8 h, 2 shifts/day | Two-shift operation. |
| Availability / utilization | 90% / 85% | Realistic field efficiency. |
| Trucks available | 8 | Used to estimate completion time. |
- Loose volume: Vloose = Vbank × (1 + Swell%)
- Effective trip capacity: Ceff = Ctruck × Fill%
- Payload limit (optional): Cpayload = MaxPayload ÷ Density
- Final effective capacity: Cfinal = min(Ceff, Cpayload)
- Travel time: t = (Distance ÷ Speed) × 60 (minutes)
- Cycle time: tcycle = tloaded + tempty + tload + tdump + tdelay
- Trips required: N = ceil(Vloose ÷ Cfinal)
- Effective working minutes: M = (Hours × 60) × Availability% × Utilization%
- Trips per truck: Trips/shift = M ÷ tcycle; Trips/day = Trips/shift × Shifts/day
- Duration: Days = N ÷ (Trips/day × Trucks)
- Trucks for a target: Trucks = ceil(N ÷ (Trips/day × TargetDays))
- Choose a unit system and enter total bank volume.
- Add swell factor to convert bank volume to loose volume.
- Enter truck capacity and a realistic fill factor.
- Provide haul distance, speeds, and fixed times per cycle.
- Set shift hours, shifts per day, and efficiency percentages.
- Enter trucks available to estimate completion duration.
- Optionally set target days to estimate required trucks.
1) Start with defensible quantities
Use surveyed bank volumes for excavation and embankment balances. A 12,000 m³ bank quantity with 25% swell becomes 15,000 m³ loose, which directly drives trips. If your quantity basis changes, update it here first before tuning cycle inputs.
2) Convert capacity to what trucks really carry
Truck body capacity is rarely achieved every trip. Apply a fill factor (often 85–100%) to represent loading variability. When density and a payload limit are available, the calculator also caps volume by weight. This prevents optimistic trip counts for wet clays, rock, or high-density aggregates.
3) Build cycle time from measurable parts
Travel time is computed from one-way distance and average speeds for loaded and empty legs. Add fixed times for loading, dumping, and average queue/spot delays. For example, 6.5 km at 28 km/h loaded and 36 km/h empty gives about 27.9 minutes of travel; adding 7.0 minutes fixed time yields a ~34.9 minute cycle.
4) Apply realistic efficiencies
Availability covers maintenance and breakdowns, while utilization covers idle time, dispatch discipline, and stoppages. An 8-hour shift has 480 minutes; with 90% availability and 85% utilization, effective working time is about 367 minutes per truck. This adjustment typically explains the gap between theoretical and field production.
5) Use outputs for staffing and schedule decisions
The calculator reports trips required, fleet trips per day, duration, and optional trucks needed for a target completion window. Use “Trucks needed for target days” to test scenarios, then validate with site constraints like loading tool capacity, dump spread limits, and traffic controls. Update speeds and delays weekly using observed cycle studies.
1) What is the difference between bank and loose volume?
Bank volume is measured in-place before excavation. Loose volume is after excavation and swelling. Trips are based on loose volume because trucks carry loosened material.
2) How do I choose an appropriate swell factor?
Use geotechnical reports, material type tables, and your project history. If unsure, run low, medium, and high swell scenarios to see how trip counts and duration change.
3) Should I use struck or heaped truck capacity?
Use the capacity that matches your operating practice and safety rules. If loads are inconsistent, keep capacity conservative and adjust with the fill factor to reflect real loading.
4) Why are availability and utilization both needed?
Availability represents mechanical readiness. Utilization represents how much of the available time is actually productive. Using both provides a more realistic estimate of daily trips.
5) How can I estimate cycle time quickly on a new site?
Start with distance and average speeds, then add typical loading and dumping times. After the first day, time at least 10 cycles and replace assumptions with observed averages.
6) When should I enter density and payload limit?
Enter them when haul units are payload-restricted or material is heavy or wet. The calculator will cap volumetric capacity by weight so trips are not underestimated.
7) Why does the estimated duration look longer than expected?
Common causes are optimistic speeds, missing queue delays, low utilization, or limited loading tool capacity. Increase delay, reduce speeds, and verify loading rates to align the model with reality.