Truck waiting & downtime ✕ Truck waiting is time spent queuing outside the loading or tipping zone. Only one truck occupies each zone. The next truck enters after the first has completed its work and cleared the zone. The percentage is the average share of each complete truck cycle spent in these queues.
Example: 30% waiting means an average of 3 minutes queuing in a 10-minute total cycle. The remaining 7 minutes cover manoeuvres, loading, travel, tipping and clearing the zones.
The figure is averaged across the fleet; individual trucks may differ. It does not automatically tell you how many trucks to remove. Compare a smaller fleet on the graph to see how productivity and cost change.
Waiting is already included in daily output. Hire cost still includes the full paid shift. Do not deduct this waiting percentage again in Work efficiency.
Servicing and breakdowns are separate mechanical downtime, accounted for under Mechanical efficiency. Rest breaks and other job interruptions have their own allowances.
Digging & swing guidance ✕ A bucket cycle includes dig and fill, swing loaded, unload and return empty. More difficult digging or a larger swing usually means a longer cycle.
CAT’s Performance Handbook, Edition 50, section 5, pages 5-24–5-25 (PDF pages 67–68), describes harder digging, greater swing angles, digging depth, truck position and obstructions as factors that increase cycle time. Its condition categories combine these effects; the handbook does not give independent multipliers for these dropdowns.
The calculator’s Easy / Medium / Hard / Very hard choices simplify that guidance. The 60% digging / 40% swing split and numerical adjustment factors are our planning assumptions, not CAT-published factors. Both the loading estimate and Analysis use the midpoint of the adjusted shorter and longer cycles. Enter a complete cycle to use field measurements instead.
Read CAT cycle-time guidance ↗
How the calculations work ✕
Size labels are rounded classes. Production uses loose body volume and bucket capacity, converted to the selected volume basis using swell. Optional loose density enforces rated payload as well as body volume. Without density, only body volume is applied.
Bucket loading = whole bucket passes × the typical midpoint cycle shown in the loading estimate. An entered complete bucket cycle overrides that estimate. Effective loose truck load is the lower of heaped body volume and rated payload ÷ loose density when density is supplied. In-ground equivalent (swell factor included) = effective loose load ÷ (1 + swell/100); swell does not increase truck body capacity.
The four stages are Loading, Loaded haulage, Tipping and Empty haulage. Loading includes manoeuvring, bucket loading, clearance and predicted loading-queue waiting. Tipping includes manoeuvring, tipping, lowering, clearance and predicted tipping-queue waiting. Additional time after a stop at queue applies only in the predicted queued zone. Each zone admits one truck until it has completely cleared.
Whole-leg haulage times include acceleration, full-speed travel and slowdown. Average haulage speed = one-way distance ÷ total leg time. Road conditions, loaded reduction and route efficiency reduce the reachable speed once. Route presets are 90%, 80%, 70%, or Custom. Entered whole-leg times bypass speed estimation and route allowances. Zone manoeuvres, clearance and queue waiting are separate from travel.
Production is limited by available trucks and the capacities of both zones. Mixed fleets use a common estimated queue delay to keep both zone utilizations at or below 100%. Delay belongs to the limiting zone, or is divided equally if both tie. Four-stage trip times use completed-load-weighted averages and add to the average round trip. Loads per day include the work-efficiency allowances. This is a steady-state estimate; individual dispatch interactions and short-lived queues at the other zone are not simulated.
Daily output = hourly production × (shift − rest) × job efficiency × operator efficiency × mechanical availability. These are separate, non-overlapping allowances: job efficiency covers work interruptions from planning, permits, design, communication and audits; operator efficiency covers productive minutes during otherwise available work; mechanical availability covers production-interrupting service and breakdowns. Rest and calculated fleet waiting must not be deducted again. Mechanical availability = operating interval ÷ (operating interval + included service downtime + breakdown downtime). One common mechanical allowance is applied to the fleet; it does not model each machine failing independently. Cost = fleet hourly rate × full shift ÷ daily output. Total job cost = unit cost × input volume; this does not round billing to whole shifts.
Completion days are equivalent working days from steady-state output; initial dispatch, final delivery, last partial loads and compaction constraints are excluded. Very small jobs need a detailed schedule.
Cycle adjustment uses a provisional 60% digging / 40% swing split. Digging factors: 0.80, 1.00, 1.35, 1.70. Swing factors at 30°, 60°, 90°, 120°, 180°: 0.60, 0.80, 1.00, 1.20, 1.60. These are planning assumptions, not CAT-published factors. Entered complete cycles bypass them.
