Jeffrey G. Benjamin

A multi-stem feller-buncher cycle-time model for partial harvest of small-diameter wood stands

Due to the increased partial harvest of small-diameter stems and the lack of feller-buncher time-consumption information in Maine, it was necessary to develop new cycle-time equations. Data were collected from seven different sites in Maine with six different operators to capture the variability in site and stand conditions as well as operator experience and proficiency. The results showed that over 55% of the trees harvested were cut in accumulations of two or more trees. Significant variables in the final model included sum of dbh and stem count per accumulation. An approach to simulate a list of accumulations with the required variables is described based on a tree list with dbh classes. Treating the combination of operator, machine, and site conditions as a random effect in a linear mixed-effects model resulted in an adjusted R 2 of 0.40 for fixed and random effects. The combination of operator, machine, and site conditions explained 32% of the variance caused by random effects. The results of this study can be incorporated into existing harvest cost prediction programs to improve estimates for this region.

Estimating Processing Times of Harvesters in Thinning Operations in Maine

Abstract Although harvester use in recent years has increased in Maine, in the past 25 years no productivity or cycle time information was made available for harvesters operating in Maines softwoo...

The effect of hardwood component on grapple skidder and stroke delimber idle time and productivity - An agent based model

We modeled the interaction between grapple skidder and stroke delimber.We developed an agent-based model using the NetLogo software.Hardwood component does not affect machine idle time under average conditions.Hardwood component has no effect on system productivity under average conditions.System productivity is most sensitive to bunch size and skidding distance. The forest industry is a capital intensive business and therefore high efficiency in management and forest operations is a must. Maine has millions of acres of forest stands with tree diameters smaller than 30cm. The harvest productivity in such stands is low compared to stands with larger diameter trees. A recent harvest productivity study in Maine identified operational constraints for whole tree harvest systems, but efforts to improve active operations would be expensive and time consuming. A common practice to reduce costs and time consumption is to develop simulation models and implement new ideas within them. We developed a production efficiency model that leverages an agent-based modeling approach. The model is based on the interaction of two common forest machines (grapple skidder and stroke delimber) and incorporates empirical cycle time estimates from research in Maine. Three scenarios have been developed to investigate baseline conditions, and two GPS and GIS aided communication improvements. The goal of this paper is to document a new agent based model and to investigate the effect of hardwood component on machine idle time and productivity. Results showed that system productivity was affected by skidding distance, bunch spacing, and removal intensity. An increase in hardwood component led to a decrease in stroke delimber idle time but did not affect grapple skidder idle time. Further, hardwood component did not affect system productivity, and none of the three single-skidder scenarios tested performed any better than another. We validated the model by conducting a sensitivity analysis to confirm previous research results. The modeled waiting times are well within the range of observed values and therefore suggest that this model is accurate and well calibrated. Our conclusions are that when operating under average harvesting conditions there is no loss in productivity due to a change in hardwood component and that a stroke delimber idle time of 40% or more is unavoidable unless the stroke delimber can work independently. Future applications of this model may target specific production forestry conditions.

Can technology help improve grapple skidder and stroke delimber interactions? A simulation approach

Grapple skidder and stroke delimber-based harvesting systems produce approximately 80% of the annual timber in Maine. Productivity studies on such systems are time consuming and often interfere with a logging contractor’s business. Computer simulations, such as agent-based modelling, represent one way to avoid interference with a logging business and to evaluate a variety of system configurations. We developed such a model to test four different operational scenarios to show whether it is possible to influence idle time, unit cost, and productivity of the system. The scenarios included a conventional skidding pattern, a modified skidding pattern assisted by an increase in operator communication and the use of Global Positioning System (GPS) and Geographic Information System (GIS), a change in delimbing behavior to decrease processing time, and the use of two grapple skidders to increase utilization of the delimber. The use of GPS- and GIS-aided operator communication did not drastically change percent idle time, productivity, or unit costs of the system. An analysis of annual cost savings showed that GPS- and GIS-aided communication between machine operators only marginally decreased the unit cost of production and in most cases resulted in an annual cost saving of less than

Challenges and Opportunities for the Northeastern Forest Bioindustry

100. Using a second grapple skidder, however, resulted in annual cost savings of upwards of

Applicability of international harvesting equipment productivity studies in maine, USA: A literature review

80,000 based on skidding distance, bunch spacing, and removal intensity. Our conclusion is that logging contractors and land managers should investigate whether or not the use of two grapple skidders can lower their unit cost of production.