Master of Science (MS)


Renewable Natural Resources

Document Type



Skidders are one of the most common timber harvesting machines used on mechanized logging operations in the southern United States and can represent the greatest single capital investment for a logging contractor. Time studies of skidders have been conducted on nearly every type of mechanized logging operation and are a key part of the productivity studies conducted on logging operation. GPS technologies have enabled researchers to move away from the typical manual time data collection for productivity studies and start conducting unattended time studies on skidding equipment. For this study a Trimble GeoXT with external antenna was installed in a skidder conducting a second thin of plantation loblolly pine. The GPS was set to record line data on a 5 second and 1 second time interval to determine which type of line file was easiest to analyze. Time data from the skidder was compared to time data collected manually on the ground to test for accuracy of the data recorded by the GPS unit. Statistical analysis was used to compare travel empty, grapple time, travel loaded, un-grapple time and total cycle time between the two methods of time data collection. It was found that GPS times were not significantly different for travel empty and grapple time, but travel loaded and un-grapple time showed significant differences between the two techniques. GPS was shown to be a useful tool for collecting data on trail work, idle time and searching for logs unsuccessfully. Also, the 5 second time interval proved to be easier and quicker to analyze that the 1 second time interval. Ideally GPS in combination with some manual time data collection on the logging deck would give the most reliable and accurate time data for productivity studies on rubber-tired grapple skidders.



Document Availability at the Time of Submission

Release the entire work immediately for access worldwide.

Committee Chair

Cornelis de Hoop