Calculating utilization rates for rubber tired grapple skidders in the Southern United States
Utilization rate is an important factor in calculating machine rates for forest harvesting machines. Machine rates allow an evaluation of harvesting system costs and facilitate comparisons between different systems and machines. There are many factors that affect utilization rate. These include mechanical delays, non-mechanical delays, operational lost time, and personnel time. As a result utilization rate can be highly variable and difficult to accurately estimate without detailed information. This paper reports on an ongoing study to measure the utilization rates for forest harvesting machines in the southern US, specifically rubber tired grapple skidders. Electronic service recorders were mounted on four grapple skidders on a harvesting operation in east central Alabama. To date, 44 working days have been monitored for three of the skidders and 19 for the fourth machine. The average utilization rate ranged from 76.5 percent to 64.8 percent.