HI. Cycle Time Calculation Guide

These notes are included as a reference for the cycle time calculations.

1 Cycle Time
2 Loader Load Time
3 Truck Load Time
4 Truck Matching
5 Truck Queue Time & Loader Hang Time
6 TKPH Delay
7 Cycles Per Charge
8 Recharge Travel Energy Usage
9 Recharge Time and Recharge Travel Time per cycle

Cycle Time

Cycle time is defined as the time for a truck to complete one return trip between any two points on the haul.

TheoreticalTruckCycleTime = SpotAtLoader + TruckLoadTime + LoadedTravelTime + SpotAtDump + DumpTime + UnloadedTravelTime + RechargeTravelTime + RechargeTime + TKPHDelay
TruckCycleTime = TheoreticalTruckCycleTime + Queue

Loader Load Time

Loader Load Time is defined as the time taken to load one truck payload. This makes it equal to the total swing time plus any delays between loading, such as the truck spot time.

LoaderLoadRate = TruckPayload / LoaderLoadTime
LoaderLoadTime = FirstPassDelay + NumBuckets * BucketCycleTime

Truck Load Time

Truck Load Time is defined as the time taken to fill the truck, exclusive of truck spot time. It is assumed that the truck is backing up under a full bucket, which makes Truck Load Time exclude the first bucket swing.

TruckLoadRate = TruckPayload / TruckCycleTime 
TruckLoadTime = (NumBuckets – 1) * BucketCycleTime

Truck Matching

The Nominal Number of Trucks is calculated as the ratio of Final Loader Rate (after overrides) over Theoretical Truck Rate (excluding queue time).

This number is then rounded or replaced according to the Truck Matching Method and any truck number overrides.

Truck Queue Time & Loader Hang Time

If the digger is over trucked, then there will be queue time.

If the digger is under trucked, then there will be loader idle time / hang time.

TKPH Delay

TKPH delays are calculated from the axle weights and truck speeds according to the formulas available in Michelin and Bridgestone handbooks.

Note that Michelin provides a temperature coefficient for calculating TKPH at different temperatures. This coefficient can sometimes be negative if the average haul speed is below 5 kilometres per hour. Essentially this means that there are no TKPH delays.

Cycles Per Charge

For trucks with Power Source set to Battery, this is the number of cycles that can be completed on a single charge.
It is roughly calculated by just dividing the battery capacity by the net energy usage per cycle.
In the special case of Battery Capacity = 0, there are infinite cycles per charge.

When Battery Capacity is not the special value of 0, the cycles per charge are more precisely calculated as:
NOTE: NetUsage here is the net energy usage per cycle EXCLUDING the energy used while traveling to the recharge.
That value is calculated after this.

Recharge Travel Energy Usage

The net energy used while traveling to recharge (RechargeTravelTime) per cycle, is then calculated then as:

Recharge Time and Recharge Travel Time per cycle

Then the Recharge Time and Recharge Travel Time per cycle are calculated using Cycles Per Charge from above as just:

See also:

Calculation FAQ