What is haul fleet utilisation, and how does it differ from mechanical availability?
Two trucks can post the same mechanical availability number and tell completely different stories on the shift report. One is parked at the fuel bay waiting on a load because dispatch backed up at the crusher. The other is grinding out cycles all shift. MA doesn't catch that difference. Utilisation does.
What mechanical availability measures
Mechanical availability (MA) is a maintenance metric. It's the share of scheduled time a truck is mechanically fit to work, calculated as total hours minus downtime for repairs and scheduled maintenance, divided by total hours. A truck sitting idle at the pit exit with a full tank and a working engine still counts as available. MA tells your maintenance planner whether the fleet is holding up. It doesn't tell you whether the fleet is being worked.
Most sites also track physical availability (PA) and use of availability (UA) alongside MA, and the three get mixed up constantly in toolbox talks. PA is availability measured against all hours in the period rather than just scheduled ones. UA is the piece that starts to bridge into utilisation: it's the proportion of available hours the truck was operated, as opposed to sitting idle but ready.
Haul fleet utilisation goes a step further than UA. It measures how much of the truck's available capacity actually went into productive haulage. A truck can be switched on, operator in the seat, moving somewhere, and still be burning hours on standby in a queue, waiting for a shovel to finish loading another unit, or idling at the dump while a dozer clears the crest. None of that shows up as downtime on the maintenance log. All of it drags utilisation down.
Where the two metrics diverge on a real shift
Picture a fleet running at 92% mechanical availability for the week, a number that would make most maintenance superintendents happy. Pull the cycle data and the trucks are only hauling productively for 61% of their available hours. The gap is queue time at the shovel, standby waiting on blast clearance, and a stretch where one haul segment turned to mud after overnight rain and cut speeds in half.
That gap is why benchmarking on mechanical availability alone misreads fleet performance. A fleet with mediocre mechanical numbers but tight dispatch and good road condition can out-haul a fleet with excellent MA and chronic queuing. If you're comparing your pit's output to a competitor's, or benchmarking one shift against another, MA won't show you where the tonnes are going missing. Utilisation, cycle time, and haul road condition will.
This is also where it gets hard without access to the truck's own systems. Mechanical availability lives in the CMMS and maintenance logs, which belong to the operator. Utilisation in its fullest sense usually comes off telematics or dispatch software: fleet management system data, GPS pings, payload sensors, all tied to a specific OEM or dispatch vendor. If you're an analyst outside the fence trying to size up a competitor's haul fleet, or an operator who wants a second read on your own site without pulling data from a system someone else controls, none of that is available to you.
What you can get from outside, reliably, is a count of trucks moving on the haul network and a read on whether the roads themselves are in a state to support good cycle times. That's the slice of the utilisation picture imagery can answer on its own, daily, without a login to anyone's dispatch system. Mine Fleet Activity turns daily VHR imagery into exactly that: a truck count on the haul network and a haul road condition read, built for benchmarking utilisation and cycle time from outside the fence.
If your benchmark needs a daily truck count and a road condition read without touching anyone's telematics, that's the gap this is built to close.