Over and Under Trucking: What is Haulage?

Created by Jeremy Callaghan - Published April 19, 2016

 jeremy-callaghan @ivolvejeremyc

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Normally mining sites will get a graduate engineer to do a time study on haulage performance. This will require the young engineer to monitor a mining circuit (1 loading unit and a number of haul trucks) in a light vehicle on a nearby bench.


What is Over and Under Trucking?

This time study will simply analyse the excavator’s performance by relating it to the cycle time of the haul trucks. An ideal haul cycle will not involve any ‘bunching’ or overtrucking of the circuit or any ‘gaps’ or undertrucking of the circuit. Being overtrucked or undertrucked in a circuit has a great impact on the cost ($/bcm) for the shift. On one hand the excavator must keep the ‘waiting on truck’ aspect to a minimum but on the other side of the coin there is no use putting an extra truck if the units ‘bunch’ or queue up.
At the very basic level he/she will log the arrival, queue, load and leaving times for later analysis through a spreadsheet. Some sites have templates with different macro enabled buttons each time a state change occurs associated with each truck. This analysis will be carried out over several hours a circuit.

Carrying out this haulage analysis is time consuming and a manual process, with the iVolve system this is all automatically carried out and presented. On the other hand, manual time study will involve several hours per circuit; logging the arrival, queue, load and leaving times for later analysis through a spreadsheet. However the data generated by iVolve is captured in real time and displayed to operators, sent to supervisors and finally is stored in the database for historic analysis by the engineers.

Ivolve reports a load cycle start time using the previous cycle’s dump time.

What are the parameters iVolve software presents?

In order of occurrence in a cycle the parameters we use to track the productivity of a circuit are:

  • Travelling empty;
  • Queing empty;
  • Spotting empty;
  • Waiting on loader;
  • Loading;
  • Travelling loaded;
  • Spotting loaded;

Each of these parameters are logged instantly and autonomously for each unit in the circuit, so any possibility of the graduate engineer falling asleep is taken out.