How to Reduce Rolling Resistance on Mining Haul Roads: The Engineering Lever That Cuts Fuel, Tyres and Cycle Times
Haul roads account for more than 50% of total mining operating costs. The haul truck fleet is the single largest consumer of diesel on any surface mine. And the single most controllable variable affecting how much diesel those trucks consume is the rolling resistance of the road surface they drive on.
Rolling resistance is the force required to overcome the retarding effect between the tyres and the road. On a perfect, smooth, hard surface, rolling resistance is minimal and almost all the engine’s power goes to moving the truck forward. On a corrugated, potholed, loose or water-damaged surface, the tyres sink into the material, flex over obstacles, and absorb energy that never reaches the drivetrain. That absorbed energy is wasted as heat in the tyres and structural deformation of the road surface — and it is paid for in diesel.
Research from the University of Queensland and CRCMining established that rolling resistance is one of the main controllable parameters for haul truck fuel consumption. A Michelin study commissioned for haul road assessment concluded that stabilised and sealed road surfaces reduce hourly fuel consumption by 3–5% on average. International research demonstrates that reducing rolling resistance from 8% to 4% on a 7.3 km graded haul road decreases capital equipment costs by 29% and operating costs by 25%. These are not marginal gains. They are among the highest-ROI interventions available to any mining operation.
This article covers the engineering fundamentals of rolling resistance on mine haul roads, the factors that drive it up, how to measure it, and the practical road surface treatments that bring it down — delivering measurable savings in fuel consumption, tyre life, cycle time and maintenance cost.
The Physics: What Rolling Resistance Actually Is
Rolling resistance is expressed as a coefficient — the rolling resistance force divided by the normal force (vehicle weight) applied to the tyre. On a well-maintained sealed road, the rolling resistance coefficient is typically 1.5–2.0%. On a well-maintained unsealed haul road, it is 2.0–3.5%. On a poorly maintained, corrugated or loose haul road, it can exceed 5–8%. On a soft, rutted or water-damaged surface, it can reach 10–15% or higher.
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Every percentage point of rolling resistance represents a direct increase in the force the engine must produce to maintain speed. For a loaded Cat 793 (gross vehicle weight approximately 384 tonnes), each 1% of rolling resistance represents approximately 37.7 kN (3,840 kg) of additional resistive force. The engine must burn additional diesel to overcome that force on every metre of every haul cycle, every shift, every day of the year.
The relationship between rolling resistance and speed is equally important. A single percentage point increase in rolling resistance can reduce haul truck speed on ramps by up to 10% and on flat sections by up to 26%. Slower trucks mean longer cycle times, fewer loads per shift and reduced production. The fuel cost of rolling resistance is therefore compounded by the productivity cost — the mine produces less while consuming more diesel per tonne hauled.
Five Factors That Drive Rolling Resistance Up on Mine Haul Roads
- Surface roughness and corrugation. Corrugation — the periodic ridges and troughs that form under repeated traffic — forces the tyre to deform over each ridge and drop into each trough. This continuous flexing absorbs energy and dramatically increases rolling resistance. Corrugation is the most common defect on unsealed haul roads and is exacerbated by dry conditions, high traffic speed and poor wearing course material. A freshly graded road may have a rolling resistance coefficient of 2.5%; within days, corrugation can push that to 4–5% or higher.
- Loose surface material. A wearing course that has lost its fine fraction to dust generation becomes a layer of loose, unbound aggregate. Tyres sink into the loose material rather than rolling across a firm surface, increasing tyre penetration depth and rolling resistance. Published research confirms that tyre penetration is the primary contributor to rolling resistance on unsealed roads — and tyre penetration is largely a function of wearing course quality.
- Moisture damage. Excessive watering for dust suppression — or rainfall without adequate drainage — weakens the wearing course and base layers. When water infiltrates below the surface, the bearing capacity of the underlying pavement is reduced. Under loaded truck traffic, the softened layers deform permanently, creating ruts and potholes. Water-only dust suppression creates a destructive cycle: the water applied for dust control is the water that destroys the road structure, increasing rolling resistance and requiring more grading, which temporarily fixes the surface before the cycle repeats.
- Inadequate compaction. A wearing course that is not compacted to the required density provides less structural resistance to tyre loading. Poor compaction can result from incorrect moisture content during construction, insufficient roller passes, or the use of material that cannot achieve adequate density. The road may appear smooth initially but deforms rapidly under heavy traffic, with rolling resistance increasing as ruts and depressions develop.
- Inappropriate wearing course material. The wearing course must contain the correct ratio of fines (clay and site binder), sand and coarse aggregate to achieve a dense, cohesive surface that resists deformation and retains its profile. Material that is too coarse ravels and loosens. Material with too many fines becomes slippery when wet and corrugates when dry. Material specification and quality control are foundational to low rolling resistance, yet many mine haul roads are constructed from whatever material is available from the pit rather than what is optimal for road performance.
Measuring Rolling Resistance: From Estimate to Evidence
Most mine sites estimate rolling resistance rather than measuring it. The standard approach uses the Caterpillar Performance Handbook tables, which assign rolling resistance coefficients based on subjective descriptions of road condition (hard, smooth and maintained; firm but not maintained; rutted or soft). This approach provides a starting point but does not capture the site-specific variation across different road sections, seasons and maintenance states.
More rigorous measurement methods include the deflection-based approach, where a Benkelman beam or falling weight deflectometer measures the surface deflection under a known load (deflection is proportional to rolling resistance), and the fuel-based approach, where GPS-enabled fuel monitoring on haul trucks is used to compare fuel consumption on different road sections under equivalent load and grade conditions. The difference in fuel consumption between a known-good section and a suspect section can be attributed to rolling resistance variation.
Modern fleet management systems on Cat, Komatsu and Liebherr trucks record payload, speed, fuel consumption and GPS position on every haul cycle. When this data is mapped to specific road sections, it provides a continuous, real-time picture of rolling resistance across the entire haul road network. Sections with consistently higher fuel consumption per tonne-kilometre are the sections with the highest rolling resistance — and the highest-priority candidates for surface treatment.
Engineering Interventions That Reduce Rolling Resistance
Polymer Soil Stabilisation: Changing the Road Material Properties
GRT7000 polymer soil stabilisation changes the properties of the wearing course material itself. Incorporated during road construction or rehabilitation, the polymer binds particles into a cohesive, dense, waterproof matrix that resists tyre penetration, corrugation, potholing and moisture damage. The treated road surface maintains its compacted profile under heavy traffic for dramatically longer intervals between grading.
The rolling resistance reduction is achieved through three mechanisms. First, the stabilised surface is harder and denser, reducing tyre penetration depth (the primary contributor to rolling resistance on unsealed roads). Second, the waterproof polymer matrix prevents moisture ingress that weakens the base layers. Third, the bound fines cannot be dislodged as dust, so the wearing course retains its optimal particle size distribution and cohesion over time rather than progressively degrading.
For mining operations, the compounding benefit is significant. Lower rolling resistance reduces fuel consumption. The same lower rolling resistance increases haul truck speed, shortening cycle times and increasing production. The stabilised surface requires less grading, freeing the grader for other maintenance tasks. And the retained fines extend the interval between gravel resheeting, deferring a major capital expenditure.
Polymer Dust Suppression: Breaking the Water Damage Cycle
GRT: Haul-Loc polymer dust suppression reduces rolling resistance indirectly but powerfully: by eliminating the need for continuous water application that damages the road surface. Water-only dust suppression requires 6–12 truck passes per road section per shift. Each pass applies 1.5–4 litres per square metre of water to the surface. This water penetrates the wearing course, weakens the base layers, and initiates the wet-dry cycling that accelerates corrugation, potholing and structural failure — all of which increase rolling resistance.
Haul-Loc reduces watering frequency by 80–90%, dosed into the water truck supply via SMART Dosing Units at a ratio of 1:10,000. The polymer remains in the road surface after the water evaporates, binding dust particles and suppressing emissions for hours to days rather than minutes. The road receives 80–90% less water, which means 80–90% less moisture damage to the pavement structure. The road holds its shape longer, corrugation develops slower, grading intervals extend, and rolling resistance stays lower for longer between maintenance events.
The combination of GRT7000 (structural stabilisation) and Haul-Loc (ongoing suppression with minimal water damage) delivers the lowest achievable rolling resistance on an unsealed mining haul road. The wearing course is bound, dense and waterproof. The surface is maintained with minimal water application. The road holds its profile under heavy traffic. And the fleet runs on a surface that minimises fuel consumption, tyre wear and cycle time per tonne hauled.
Rolling resistance and fuel savings: illustrative calculations for a 20-truck fleet
| Parameter | Untreated Road (5% RR) | Well-Graded (3.5% RR) | Polymer-Stabilised (2.5% RR) | Saving (Untreated → Stabilised) |
| Rolling resistance coefficient | 5.0% | 3.5% | 2.5% | 2.5 percentage points |
| Fuel consumption impact (loaded, flat haul) | Baseline | ~3–5% reduction | ~8–12% reduction | 8–12% less fuel per truck |
| Fleet diesel (20 trucks × 700,000 L/yr) | 14,000,000 L | 13,300,000–13,580,000 L | 12,320,000–12,880,000 L | 1,120,000–1,680,000 L saved |
| Fleet fuel cost (@ $2.80/L) | $39,200,000 | $37,240,000–$38,024,000 | $34,496,000–$36,064,000 | $3,136,000–$4,704,000 saved/yr |
| Tyre life extension (25% documented) | Baseline (set life × 20 trucks) | 10–15% improvement | 25% improvement | $1,500,000–$2,250,000 saved/yr |
| Grading frequency | Daily–every 2 days | Every 3–5 days | Weekly–fortnightly | 75% less grader hours |
For a 20-truck fleet on a typical Australian open-pit operation, the combined fuel and tyre saving from reducing rolling resistance through road stabilisation is approximately $4.6–$7.0 million per year — before accounting for reduced grading costs, increased production from shorter cycle times, and improved haul truck mechanical availability from reduced vibration and component fatigue.
The Decarbonisation Dividend: Rolling Resistance and Scope 1 Emissions
Every litre of diesel not burned by a haul truck is approximately 2.68 kg of CO₂e not emitted. For the 20-truck fleet example above, reducing rolling resistance through road stabilisation eliminates 1,120,000–1,680,000 litres of diesel per year — equivalent to approximately 3,000–4,500 tonnes of CO₂e per year.
For mining operations reporting Scope 1 emissions under the National Greenhouse and Energy Reporting Act, the Safeguard Mechanism, or voluntary frameworks such as TCFD and the ICMM Climate Change Statement, this is a deployable, measurable, low-cost decarbonisation lever. Unlike fleet electrification (which requires multi-year capital programmes and technology maturation), road surface improvement delivers emissions reductions within months of implementation, using existing equipment, with immediate payback.
The combination of reduced haul truck diesel (from lower rolling resistance) and reduced water truck diesel (from fewer watering passes) represents one of the highest-impact, lowest-cost Scope 1 reduction opportunities available to any surface mining operation. GRT’s published analysis documents combined CO₂e reductions exceeding 15,000 tonnes per year on a single operation when both haul road stabilisation and polymer dust suppression are implemented together.
The Road Surface Is a Production Lever, Not a Maintenance Item
Rolling resistance is not a road maintenance problem. It is a production, fuel, tyre, emissions and cost problem that happens to be caused by the road surface. When mine management treats the haul road as a production asset rather than a maintenance liability, the ROI case for surface investment becomes compelling: $3–$7 million per year in fuel and tyre savings alone for a typical 20-truck fleet, with additional returns from reduced grading, increased production and measurable Scope 1 emissions reduction.
GRT7000 soil stabilisation and GRT: Haul-Loc polymer dust suppression, delivered through SMART Dosing Units, provide the integrated approach: a structurally sound wearing course that resists deformation, maintained with minimal water application that does not damage the pavement, and automated dosing that ensures consistent performance across shifts. The result is a road surface that stays at 2.0–2.5% rolling resistance rather than cycling between 2.5% (freshly graded) and 5–8% (degraded) — and a fleet that runs as efficiently as the road allows, every day.
Sources and References
UQ/CRCMining: Adair et al. — Rolling Resistance in Haul Truck Operations (ResearchGate, 2015)
Mining Doc: Soofastaei et al. (2018) — The Effect of Rolling Resistance on Haul Truck Fuel Consumption
GRT: GRT7000 — polymer soil stabilisation
GRT: GRT: Haul-Loc — polymer dust suppressant
GRT: SMART Dosing Units
