Why quarry tracks corrugate and why vehicle choice is the cure
First published in the November 2025 issue of Quarry Management as Don't get into a Rut
By Russell Peterson, co-founder and chief executive officer of Munro Vehicles
It was talking to one of our customers that created a lightbulb moment for me: ‘When we used coil-sprung 4x4s in the mine, the roads did not suffer from corrugations, but now we are using leaf-sprung pickups, they corrugate so quickly between gradings.’
Unmetalled tracks in quarries and mines take a daily pounding. Heavy loads, repeated routes and steep gradients all play their part, but a quieter culprit often does the most harm: road-biased 4X4s and pickups running basic leaf-spring suspension. These vehicles are attractive on purchase price, yet their suspension design encourages bouncing and axle tramp. The same wheels hit the same patches of track in the same way, again and again, corrugating the road, making it unpleasant to drive on and rapidly accelerating wear, slowing down operations. What looks like a saving at the gate quickly becomes a bill for graders, fresh aggregate, damaged vehicles and lost time.
Leaf springs were devised for simplicity and cost. They can carry weight, but they are stiff and offer limited control of rebound. On rough ground, especially when lightly loaded, a leaf-sprung axle tends to hop. That hop is axle tramp: a rapid oscillation that breaks and reforms the tyre’s contact patch. Each oscillation hammers the surface at a similar spacing, which is why you see washboarding and scalloped ruts setting in along familiar routes. As the track deteriorates, drivers back off, then throttle on to ‘skip’ across the corrugations, which worsens the cycle. Ruts deepen, water collects, and the base weakens. Before long, a track that was serviceable on Monday demands attention by Friday.
There is another cost hidden in these ruts: fatigue and downtime. Drivers who are forced to endure constant vibration tire more quickly, and vehicles spend more time off the road with broken mounts, cracked brackets and prematurely worn bushings. Tyre damage rises as larger, sharper aggregates are worked to the surface. None of this is inevitable. It is, in large part, a consequence of using 4x4s designed primarily for tarmac with only occasional off-road excursions in mind.
Munro’s electric 4x4s were engineered from the ground up for off-road work. Rather than relying on cheap leaf packs, the company’s engineering team specified a robust spring and damper set-up that is tuned to control wheel movement over rough surfaces. Well-matched damping prevents the uncontrolled rebound that creates axle tramp, so tyres stay in contact with the ground and energy is not fed back into the track at the same repetitive spacing. The result is sure-footed traction, a comfortable ride for crews and, crucially, a dramatic reduction in rut formation and surface corrugation. When vehicles do not hop, tracks do not deform in the same way.
Comfort matters for productivity. A compliant, well-controlled suspension reduces whole-body vibration and driver fatigue, helping crews to stay alert and effective through long shifts. Control also equals safety: with consistent tyre contact, steering and braking feel and remain predictable on loose surfaces, even when conditions change with weather or traffic. Because Munro’s vehicles are equally at home on the road, teams can move between public roads and site tracks without compromise.
Durability is another hallmark. Munro vehicles are engineered to last and to be easily repairable in the field. Their layout is straightforward, components are accessible, and wear parts are selected with hard use in mind. In remote or time-critical operations, the ability to diagnose and fix issues on site can be the difference between a minor pause and a day’s lost output. Electric drivetrains add their own resilience: fewer moving parts, no diesel particulate filters to clog or AdBlue systems to top up, and strong low-speed control that reduces driveline shock. Regenerative braking can also ease the load on friction brakes on descents, cutting wear to pads and discs, as well as reducing fuel use.
All of this feeds into the metric that matters to quarry and mine operators: total cost of ownership. The initial capital expense is only one line item. Track maintenance, vehicle downtime, tyre and brake wear, fuel or energy costs, and the health and performance of crews all sit on the same ledger. A cheaper, road-biased 4x4 can look attractive on day one but cost far more over its operating life through accelerated track degradation and higher maintenance. By contrast, Munro’s purpose-built electric 4x4s protect the asset you drive on as well as the asset you drive. They help keep tracks in better condition for longer, reduce the frequency and intensity of remedial works, and keep crews moving efficiently.
There is a broader sustainability dividend too. Minimizing rutting reduces sediment run-off and preserves drainage, helping sites manage water more effectively after heavy rain. Electric propulsion removes tailpipe emissions, improving air quality around working areas and reducing the carbon footprint of day-to-day logistics. These gains arrive without asking operators to change how they work. The vehicles simply do their job, better.
Traditional 4x4s are generally designed for mainly on-road use with a little off-road capability added. Munro’s electric 4x4s invert that logic. They are designed primarily for off-road use, with the robustness, control and comfort that entails, and they remain entirely civilized on the road. For operators who are tired of paying twice, once for a cheaper suspension and again for the damage it inflicts, the choice is clear. Choose vehicles that work with your tracks, not against them, and let total cost of ownership guide the decision rather than initial price alone. Your crews, your balance sheet and your site infrastructure will all feel the difference.
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