|Summary: The main problem studied in this paper was the accuracy of determination of forest area centres by the application of known methods and by means of a personal computer. Determination of medium dragging distances represents one of the facotrs neeed to determine, as accurately as possible, the working cost for building a network of drag roads. In other words the accessibility of forests should be based on a correct regional design and planned network of forest drag roads with optimal density. In fact, by reducing to a minimum level the costs of dragging and transport, drag road construction and their maintenance, it is possible to reach an optimal solution for the problem of road accessibility. This paper describes one of the possible ways of determining the medium distances from the central dragging point by the application of a personal computer. The aim of the study was, for the realized orographic, hidrographic, stand characteristics and other properties of a particular forest land, to process one existing compartment (Compartment 64 of the Managemental Unit »Južna Garjevica«). Digital models of terrain were worked out on the terrain were worked out. On the basis of existing forest-managment and topogaphic maps. By meansof this digital modelof maps. By meansof this digital model of terrain the forest area was shown in 3-D, namely 2-D, projection and included the projected network of the tractor skidding roads of different longitudinal inclination. Projected variants of the skidding road: 12.5 -15.0 - 17.5 and 20.0 take up 3.32 3.67 of the productive forest land area. The medium dragging distance, according to the Basis of Management, should be 350 m, while with this investigation we arrived at a value of 299.56 m as the most suitable, that is optimal variant of 17.5. The density of skidding roads ranged between|
94.98 up to 104.81 m/ha, and the optimal one was selected maesuring 100.91 m/ha. With the application of a personal computer it is possible to fullz simultate existing conditions in the field, reaching a high degree of accuracz, and in this way, during the data processing, existing situation in reality. The accuracy of work is unquestionable and consequently it can be concluded that further elaboration and usage of personal computers in the aformentioned field should be continued. Furthermore, it is expected that in the process of further practical application new simple, and even more accurate methods than these presented in this paper, will be realized.