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Nowadays, economical, technical and ergonomic factors have a great importance on the design of the agricultural tractors. The paper illustrates the use and the management of heterogeneous product information (manual measurements and drafts, 2D drawings, technical documentation, photos), advanced CAD modeling tools and digital human models, for the redesign and the ergonomic optimization of an agricultural tractor’s driver cab. The project development has been organized using a top–down approach in a collaborative environment. At first, a manual measurement with gauges allowed to realize a technical draft of the whole agricultural tractor and of each component part of the driver cab. Then a main skeleton has been created in Catia V5 environment in order to specify all the datum elements necessary to model each sub-assembly of the tractor. Cabin, platform, engine, tires, seat, dashboard and controls have been organized separately and modeled considering the details related to the manual measurements and to the technical standards. Once obtained the 3D CAD model of the tractor, an opportune questionnaire was prepared and a test campaign was carried out with real operators in order to define the more critical control devices within the driver cab, as regards to usability and ergonomic issues. An “Ergonomics’ Evaluation Index” (EEI) was defined taking into account the posture angles of the operator and the Rapid Upper Limb Assessment analysis tool available in the “Ergonomics Design & Analysis” module of Catia V5 based on the use of a digital human model. The index was validated comparing the results of tests carried out using virtual manikins of different percentiles performing a specific driving task, with the results of tests carried out by real operators, of the same percentiles, performing the same driving task. Critical values of the EEI obtained during some driving tasks in virtual environment, suggested to modify the shape and the position of some control devices in order to optimize the ergonomics of the driver cab. The adoption of the top-down modeling based approach allowed each change on a singular component part to be automatically propagated on the whole assembly, making easy the changes on the virtual prototype.

Construction of forest roads can cause shortterm and long-term negative effects on forest ecosystems in different ways if they are not well planned and appropriately maintained. In this research, environmental damages caused by an excavator during road construction were examined in steep terrain covered by beech (Fagus orientalis L.) stands. The study was conducted along a 1.5 km road in western Blacksea Region of Turkey. All of the road construction operations were monitored during a construction period, and measurements of cross sections sizes and stand damages were measured during and after the construction activities. The road construction was evaluated according to the appropriate method and standards. The average widths of roadway, fill slope and construction zone were 4.82, 6.91, and 16.61 m, respectively. Along the 1,500 m road, forested area impacted was 24,915 m 2 while the number of trees cut was 1,495 and rate of the damaged trees below the fill slope was found to be 24.7 %. In the study, based on the appropriate method and standards, less forested area might have been impacted (23 %). As a result of regression analysis, it was found that the rate of damaged trees increased as the values of the proportion of rocks, the width of the road surface and the width of the cut-slope increased. To reduce the negative effects of forest road construction on the environment, new forest road construction by excavators should be performed using appropriate methods within mountainous terrains.