Engineering & Mining Journal

JUL 2019

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Page 46 of 67

HAUL ROAD MANAGEMENT JULY 2019 • E&MJ 45 To better understand the penalty associated with increased roll- ing resistance, let's consider two different scenarios (See Figure 2): hauling up a 10% ramp road laden (orange line) and a flat haul laden (red line). Looking at the percentage increase in cycle time associated with rolling resistance (y axis), when rolling resis- tance increases from 2% to 3%, the cycle time increases by 7% for the ramp haul and 20% for the flat haul. Similarly, a 2% to 3% increase in rolling resistance causes a 7% and 25% increase in fuel burn for the ramp and flat hauls, respectively. It becomes obvious where a significant investment is justified to improve road conditions, either through re-sheeting or re-construction. Many of the decisions related to haul road management re- late to rolling resistance, how we measure it and how we trans- late those measurements into a rolling resistance value, Thomp- son explained. "Unfortunately, it's a real problem to measure," Thompson said. "In an ideal world, everyone would use the In- ternational Roughness Index (IRI) and monitor the roads with drones equipped with high-resolution cameras, but most of us have to work with what we are given and that's not much." One of the approaches to measuring rolling resistance is the qualitative defect evaluation. As part of that process, the defects that contribute the most to rolling resistance are recorded and assessed against a benchmark. "This not only serves as a roll - ing-resistance benchmarking exercise, but it's a great training tool for supervisors and operators to understand the impact of those road defects on the entire operation," Thompson said. Another method for determining rolling resistance is quan- titative wearing course testing. Usually a 20-kg sample of the Mining haul roads are a critical component of surface mining infrastructure and the perfor- mance of these roads has a direct impact on operational efficiency, costs and safety. A sig- nificant proportion of a mine's cost is associ- ated with material haulage and well-designed and managed roads contribute directly to re- ductions in cycle times, fuel burn, tire costs and overall cost per ton hauled and critically underpin a safe transport system. The first comprehensive treatise on min- ing haul road design, construction, opera- tion and management, Mining Haul Roads – Theory and Practice, presents an authori- tative compendium of worldwide experience and state-of-the-art practices developed and applied over the last 25 years by the three authors (Roger J. Thompson, Rodrigo Peroni and Alex T. Visser), over three continents and many of the world's leading surface mining operations. Mining Haul Roads – Theory and Practice is a complete practical reference for mining operations, contractors and mine planners alike, as well as civil engineering practi - tioners and consulting engineers. It will also be invaluable in other fields of transportation infrastructure provision and for those seeking to learn and apply the state-of-the-art in min- ing haul roads. Mining Haul Roads – Theory and Practice Figure 3 — At some point, a haul road will reach the stage where, no matter how much maintenance work is performed on it, the rolling resistance will not improve. That's when the mine should consider a re-sheeting campaign.

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