Load, haul & blast Guide
Haul truck cycle time: the parts and how to measure them
Haul truck cycle time is queue, spot, load, haul, dump and return, plus delays. How to measure each part, with a worked trucks and tonnes per hour example.
Contents 7 sections
Haul truck cycle time is the time from one arrival at the loader to the next: queue, spot, load, haul loaded, queue and dump, and return empty, plus delays. Loads per truck per hour is operating minutes divided by cycle time, and tonnes per hour is that number times the payload. Queue time is the part that grows when a circuit has more trucks than its loader can fill.
Caterpillar splits the cycle into fixed time (loading, the truck exchange at the loader, and manoeuvring and dumping) and variable time (the loaded haul and the empty return), and notes that “wait time, delays and operator efficiency all impact cycle time” (Caterpillar Performance Handbook 50, p. 8-5, read 25 Sep 2026).
The parts of a haul truck cycle
Measure the cycle in the parts below. Each has a clear start and end, so two people timing the same truck get the same answer.
| Part | Starts | Ends | What drives it |
|---|---|---|---|
| Queue at loader | Truck arrives at the loading area | Truck starts reversing in to spot | More trucks than the loader can serve; loader stops |
| Spot (truck exchange) | Truck starts to spot | Truck stops under the bucket | Loading area layout, single or double-sided loading |
| Load | First bucket | Last bucket, truck pulls away | Bucket size, passes, fragmentation, operator |
| Haul loaded | Truck leaves the loader | Truck arrives at the dump or tip | Distance, grade, rolling resistance, speed limits |
| Queue at dump | Truck arrives at the dump or crusher | Truck starts to reverse | Crusher availability, dozer on the dump, tipping bays |
| Manoeuvre and dump | Truck starts to reverse | Body down, truck pulls away | Dump layout, material sticking in the body |
| Return empty | Truck leaves the dump | Truck arrives back at the loading area | Distance, grade, road condition |
| Delays in the cycle | Any stop between the points above | Truck moves again | Intersections, waiting for road crossings, water cars, blasting holds |
Caterpillar gives typical figures for two of these: truck exchange at the loader “typically 0.6-0.8 min.” and manoeuvre and dump “typically 1.0-1.2 min.” (Performance Handbook 50, p. 8-5). A 2024 study of an open-pit operation in Eritrea splits the queue in the same way, counting queuing, positioning and loading as the loading time and queuing, positioning and unloading as the unloading time (Mnzool et al. 2024, read 25 Sep 2026).
Stops outside the cycle belong in a different bucket. Shift changes, meal breaks, refuelling, pre-start checks and breakdowns reduce the operating minutes in an hour. Mixing them into cycle time makes the cycle look slow when the problem is lost hours, which is an availability and utilisation question.
How to measure cycle time
There are three sources of cycle data on most sites. Use the one you have, and check it against a second one for a shift or two.
| Part | Dispatch system | Telematics and onboard payload system | Manual time study |
|---|---|---|---|
| Queue at loader | Status changes (waiting, spotting) entered or inferred at the shovel | Speed near zero inside the loading area before the payload starts rising | Stopwatch from arrival to reversing |
| Spot | Spotting status | Reverse gear or low speed inside the loading area | Stopwatch |
| Load | Loading status, bucket count from the loader | Payload rising from empty to loaded; time of each bucket if the loader is instrumented | Stopwatch, count passes |
| Haul loaded | Loaded travel status | Loaded payload, speed above a threshold, position between the two areas | Radio calls or clock times at each end |
| Queue at dump, manoeuvre and dump | Dump status | Body-up event, payload falling to empty | Stopwatch at the dump |
| Return empty | Empty travel status | Empty payload, speed above a threshold | Clock times at each end |
| Delays | Delay codes entered by the operator or controller | Stops with speed at zero outside the load and dump areas | Observer notes the reason |
Onboard payload systems on large trucks record more than weight. Caterpillar describes its system as using “strut pressure sensors and an on-board micro-processor to determine payload weight, cycle segment times, delay times, actual clock time and date of each cycle” (Performance Handbook 50, section 8). Where the trucks carry that system, the cycle parts are already being logged: the work is getting the records out and lined up with the load count.
Plain GPS works too. A study for Iowa State University attached GPS trackers to trucks, an excavator and a dozer, and “cycle times were determined by defining the haul boundary, dump locations, and loading locations”, with “the cycle time … defined as the difference between the times of two loading points” (Iowa State University 2016, read 25 Sep 2026). Draw the loading area and the dump as zones, then read the time each truck enters and leaves each zone.
A manual time study is the check on both. One person at the loader and one at the dump, each with a watch set to the same time, can time 20 to 30 cycles in a morning. The Mnzool study recorded start and end clock times for each cycle on site.
Two things catch people out when they read the results:
- Cycle times are skewed. The Iowa study found the distributions “positively skewed” and “none of the distributions are normal”. A few long cycles pull the average up. Report the median and the average together, and look at the long cycles for their cause.
- Short stops add up. The same study found trucks stopping “for a short period (e.g., two minutes)” while “yielding to other equipment and waiting for direction”. Set a minimum stop length, say 30 seconds, and count every stop above it as a delay with a reason.
From cycle time to trucks per hour and tonnes per hour
Cycle time (min) = queue at loader + spot + load + haul loaded + queue at dump + manoeuvre and dump + return empty + delays
Loads per truck per hour = operating minutes per hour ÷ cycle time (min)
Tonnes per truck per hour = loads per truck per hour × payload (tonnes)
Tonnes per hour for the circuit = the lower of: (number of trucks × tonnes per truck per hour) and (loader’s maximum loads per hour × payload)
Caterpillar’s handbook works production with a 60-minute hour and then applies an efficiency factor, and its excavator example uses “a 50 min. work hour (83% job efficiency)” (Performance Handbook 50, p. 5-29). Use your own site’s operating minutes per hour once you have measured them. The worked example below uses 50.
What queuing at the loader does to cycle time
Take the queue out of the example and the cycle is 20.5 minutes. At that cycle, each truck could deliver 50 ÷ 20.5 = 2.44 loads an hour. The loader can serve 16.7. Dividing one by the other says the loader can keep about 6.8 trucks busy. Every truck above that waits.
| Trucks on the circuit | Cycle time (min) | Queue at loader (min) | Tonnes per truck per hour | Circuit tonnes per hour | Truck hours per 1,000 tonnes |
|---|---|---|---|---|---|
| 6 | 20.5 | 0.0 | 146 | 878 | 6.8 |
| 7 | 21.0 | 0.5 | 143 | 1,000 | 7.0 |
| 8 | 24.0 | 3.5 | 125 | 1,000 | 8.0 |
The figures are illustrative and follow from the worked example above.
Going from 8 trucks to 7 moves the same 1,000 tonnes an hour with one truck fewer: 12.5% fewer truck hours, with the diesel and wear that go with them. Going from 7 to 6 costs about 12% of output, because the excavator now stands waiting for trucks. The right number is the smallest fleet that keeps the loader busy. Match factor is the ratio that puts a number on this balance.
This simple table assumes trucks arrive evenly. In practice they bunch behind a slow truck on a ramp, after a crib break or after a delay at the dump, and a bunch arrives at the loader together. So a real circuit shows some queue time even when it is short of trucks, and a circuit with too many trucks shows more queue than the arithmetic predicts. Uneven payloads are another source of uneven cycles (see payload management).
Queue time at the dump works the same way. When a crusher stops or a dozer is slow to clear the tip, trucks wait at the dump, and the effect flows back round the circuit to the loader.
Checklist: reading your own cycle times
Cycle time feeds straight into cost per tonne. A truck hour costs the same whether the truck is hauling or queuing, so queue minutes add cost to every tonne moved.
Common questions
What is a normal haul truck cycle time?
There is no single normal figure. Cycle time depends on haul distance, grades, road condition, the loader and the number of trucks on the circuit. Compare a circuit with itself over time, part by part, and compare the loading and dump parts across circuits that share a loader or a dump.
Should queue time be counted in the cycle?
Yes. Queue time is part of every cycle the truck completes, so it sits inside cycle time and lowers trucks per hour. Record it as its own part so it can be seen. Out-of-cycle stops such as breaks, refuelling and breakdowns are kept separate, as lost operating minutes.
Why does adding a truck not always add tonnes?
Once trucks arrive faster than the loader can spot and load them, the loader sets the output. An extra truck then adds queue time to every truck’s cycle and moves no extra tonnes.
Sources
- Caterpillar, Caterpillar Performance Handbook, Edition 50 (SEBD0351-50), June 2022, pp. 5-29, 8-5 and 25-18. Read 25 Sep 2026.
- Mnzool, M. et al., Optimization of cycle time for loading and hauling trucks in open-pit mining, Mining of Mineral Deposits 18(1), 2024, pp. 18-26. Read 25 Sep 2026.
- Iowa State University, Institute for Transportation, Earthwork Haul-Truck Cycle-Time Monitoring: A Case Study, Final Report, March 2016. Read 25 Sep 2026.
