The OEM onboard data logging system logs payload, empty stopped time, empty travel time, empty travel distance, loading time, loaded stopped time, loaded travel time, loaded travel distance, total cycle distance, total cycle time, and fuel used for each cycle. The research team downloaded data from May 3 to July 2, 2010. The summary performance was based on all of this data. However, given the variability in haul distances, haul road profiles, and haul road conditions, only data from the June 28-July 2 experimental period were used for detailed analysis. This was because haul distances, profiles, and conditions were similar during that period. The haul profile was surveyed with Topcon Hyperlite GPS units for real-time kinematic (RTK) surveying. Even though the OEM system logged cycle times, manual time and motion studies of the trucks were conducted as well to validate data from the OEM system. The OEM data proved to be reliable and better than the manual data. Therefore, all analyses were based on OEM data.
First, statistical hypothesis testing at 95% confidence was used to determine if different operators and trucks had any impact on fuel consumption and total cycle time. Subsequently, statistical correlation analysis was used to evaluate the correlation between fuel consumption and payload, as well as between fuel/cycle per ton and the components of cycle time (i.e. empty stopped time, empty travel time, loading time, loaded stopped time, and loaded travel time). Regression analysis was then used to determine the relationship between fuel consumed/ton per cycle and components of cycle time.