Performance and Cost Evaluation of Split–Local Material Mixtures for Coal Hauling Road Pavements: A Case Study in Coal Mining Operation

Abstract

Hauling road performance plays a critical role in maintaining productivity, safety, and cost efficiency in mining operations, particularly under heavy traffic and adverse weather conditions. In coal mining areas, haul roads are frequently subjected to high axle loads, moisture-induced deterioration, and rapid loss of bearing capacity. This study investigates the effectiveness of haul road strength improvement using a mixture of split stone and locally available material known as okes through a field-based case study in a coal mining operation in Central Kalimantan, Indonesia. The hauling roads were designed to accommodate haul trucks with gross vehicle weights of up to 46 tons and an average traffic volume of 200 trips per day, supporting an annual production target of approximately 800,000 tons. Two pavement improvement methods were evaluated: a conventional Split+Basecourse mixture and an alternative Split+Okes mixture. Road performance was assessed using key indicators including California Bearing Ratio (CBR), slippery road duration after rainfall, surface deformation, and cost efficiency. The results show that both methods significantly improved road performance by reducing slippery conditions from four hours to one hour and increasing CBR values from below 10% to 72.94% and 64.50%, respectively. Although the conventional method achieved higher CBR values, the Split+Okes method delivered comparable operational performance with approximately 26% lower material cost. The findings demonstrate that the use of locally sourced materials provides a technically viable, cost-efficient, and sustainable solution for haul road improvement in mining operations.