Shawn A. Baker

Productivity and Product Quality Measures for Chippers and Grinders on Operational Southern US Timber Harvests

Abstract Growth in bioenergy interests in the southeastern United States has created a need for cost-effective woody biomass harvesting systems. We evaluated three operational systems for their potential production and cost: horizontal grinders fed with residue from roundwood harvests, horizontal grinders fed with residue from clean chipping harvests, and whole tree chippers fed with entire stems. We evaluated three contractors operating each of the three system types over the course of approximately one working week each. Utilization rates for chippers and grinders were 44% and 38% respectively. Hourly production ranged between 22 – 30 metric green tonnes (gt)/SMH and 64 – 70 gt/PMH and did not differ significantly between the three systems. Delivered costs per gt of material were also very similar for the three systems and ranged between

Cost and Productivity Impacts of Product Sorting on Conventional Ground-Based Timber Harvesting Operations

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Analysis of Log Hauling Vehicle Accidents in the State of Georgia, USA, 1988–2004

23.81.

Individual stem value recovery of modified and conventional tree-length systems in the southeastern United States

The impacts of additional log sorting on production and cost per ton for mechanized, tree-length southern pine harvesting systems were evaluated. The analysis included evaluation of extensive data sets of weekly production along with short-term field time studies to directly measure the impacts of sorting on production. For this study, a product separation, or sort, was defined as a separate pile generated by the loader operator. The data were used to create a model to evaluate log sorting impacts on production and costs. Tree-length harvesting systems encountered weekly production losses when sorting more than six products, while modified tree-length harvesting systems using roadside processors lost production after nine product sorts. Hourly production was significantly impacted by both operator technique and the type of product handled. Operators who processed wood in advance of truck arrivals and loaded trucks from processed piles loaded trucks in 60 percent less time than loader operators who processed stems while loading. Increasing the number of sorts often required more processing while loading since the room to store processed wood under stationary loaders is limited. Adding precut sorts significantly reduced production over that seen with an additional tree-length sort, due to the additional processing and loader movement with multiple stem pieces. With the current product price differentials typical to southern log markets, we did not find increased net revenue to the landowner from additional sorts. In fact, we found that at current prices additional sorts can reduce revenue by 6 to 15 percent.

Evaluation of integrated harvesting systems in pine stands of the southern United States

Abstract Mechanical failure rates associated with logging vehicle accidents in Georgia are dramatically lower today than they were in 1988–1991 before these trucks became subject to random roadside inspections. Mechanical failure dropped by half for logging tractor-trailers (from 10.9% to 4.8%) and by two-thirds for logging trucks (from 12.9% to 4.2%). Mechanical failure is now the seventh most cited contributing factor in logging tractor-trailer accidents instead of first as it was prior to 1991. Specific types of mechanical failures have also declined sharply. Three potential failure items that are visually checked during roadside inspections - brakes, slick tires, and lights - have seen the most dramatic declines. Brake failure has dropped by two-thirds and improper lights as a factor have almost disappeared. Driver impairment due to use of alcohol or drugs today occurs in less than 0.5 percent of accidents. Factors associated with logging vehicle accidents today in Georgia closely resemble those associated with all trucking accidents generally. Accidents per million tons of wood consumed, however, has increased steadily from 11 in 1991 to 19 per million tons in 2003.

In-wood grinding and screening of forest residues for biomass feedstock applications.

Abstract We compared value recovery of a modified tree-length (MTL) logging system that measures product diameter and length using a Waratah 626 harvester head to that of a tree-length (TL) system that estimates dimensions. A field test compared the actual value cut to the maximum potential value suggested by the log bucking optimization program Assessment of Value by Individual Stems (AVIS) for 25 felled trees on each of three sites for two loggers. One half of each site was harvested with a TL crew and the other half with a MTL crew. ANOVA on individual stems using site as a blocking factor showed significant differences between TL and MTL, with TL recovering 80.3% and MTL recovering 73.7% of total value after downgrades.