Effect of Truck Payload Weight on Production

Most constructors intuitively understand that there is a relationship between payload weight and haul unit performance. At the same time, project managers constantly push the limits of rated truck payload as they seek increased productivity. This is because it is believed that increased productivity translates into reduced project cost. These ideas are quantitatively examined using payload data from seven Caterpillar 785B off-highway haul trucks working on an earth/rockfill dam in California. Caterpillar's Vital Information Management System was used to collect load data from 54,300 truck cycles representing approximately 14,419 operating hours and haulage of more than 7.25 million metric tons (8 million tons) of material. There was a diminished productivity increase when the load weight exceeded the truck's rated gravimetric capacity. Adding sideboards actually caused the average monthly production of the fleet to decrease. The plot of load times versus load weight appears to indicate a human factors relationship between load time and providing the shovel operator load weight information with indicator lights mounted on the trucks.