A comprehensive study at an off-forest central processing yard has answered this question.
The research was carried out at a Pinus radiata processing yard. 214 work shifts were analysed. The equipment used was a scanning optimiser and two mechanised processors. The work day consisted of two shifts, with the first mainly being in daylight hours and the second mainly during night hours. The yard was well lit with floodlights. It received delimbed stems, or segments thereof, for processing. These were then passed through a mobile optimising plant, known as a Logmeister, consisting of a loader, a scanner, and log-bucking machines. The scanner generates a stem profile and an operator then enters changes in wood-quality codes. Using this information, the stems are then bucked using a processing head mounted onto an excavator. This study investigated the scanner operators and the log-bucking processors. The system operated five days per week with two shifts per day. The first shift for the scanner operator was 9.5 hours and ran from 04h00 to 13H30. The second shift started at 14h00 and usually ran until 22h00. The shift lengths for the processors were normally 8 to 12 hours.
The time of time of day had no overall productivity impact. The scanner volume productivity was influenced by the time of day, but this was found to be related to the average piece size being handled, the number of machines being used, or operator differences. The lack of substantial differences was thought to be as a result of good overhead lighting and the scanning system that had less reliance on human input.
The research was titled “Time of day impacts on machine productivity and value recovery in an off-forest central processing yard”. It appears in the New Zealand Journal of Forestry Science, Vol. 44(19), 2004. The authors were G Murphy, H Marshall and A Dick. For a more complete account of the research, please access http://www.nzjforestryscience.com/content/44/1/19