The trolley assist systemTrolley assist system enables the supplySupply of electric power directly to the drive system of diesel-electric haul trucks, thereby increasing productivity, reducingReducing diesel consumption, and reducingReducing CO2 emissionsEmissions. CopperCopper Mountain MineMine in British Columbia, the first mineMine in North America to install the trolley assist systemTrolley assist system, has installed an overhead power supplySupply system along an inclined haul road segment stretching approximately 1 km and operates 28 diesel-electric haul trucks, 7 of which are equipped with pantographs to receive electricity. The purpose of this paper is to report the actual improvements at the mineMine by comparing operating results of trolley assisted and non-trolley assisted haul trucks. There was a 10% increase in the productivity of the haulage operationOperation as a contribution of 59% increase in the climbing speed on the segment with the trolly assist system. In addition, the operating costOperating Cost per tonne moved was reduced by 16% and CO2 emissionsEmissions per cycle were reduced by 42%.