Using environmental parameters for planning forest roads network

Nowadays designers are designing forest roads using digital models for mountainous areas in order to save time and cost. On the other hand, using traditional methods due to low precision and speed are decreasing day to day. On the other hand the combining different layers of information require time and high precision. Special features of this research is using of road experts opinions in the northern departments of Natural Resources and using all the information needed to design forest Road in north of the country.
This research aims to introduce an appropriate method with emphasizing on technical and environmental perspectives for forest road planning using GIS and AHP methods. Therefore, 8 maps layer include slope, aspect, altitude, stock, soils type, hydrographic, geology and pedology were determined for the study area. Factors affecting the design by using GIS Software and were also extracted the constraints in the form of a friction layer. Then was performed weighting each of the parameters using the Analytic Hierarchy Process (AHP) and was obtained coefficient of importance of each parameter using Expert Choice software and then was produced suitability map for road construction considering the coefficient of importance of parameters and its impact on information layers and overlapping them by GIS Software. Then the road was planned on the incorporated proposed map.
The results of this study indicated that the existing roads are not suitable in density and coverage perspectives. Only 16% of existing roads were passed with high stability areas.
Taking into account all environmental and technical issues we can state that, third designed road in comparison with existing roads and other designed roads, has superior so it could proposed in this study as the best variant. But it cannot be claimed with absolute certainty that designed roads are fit perfectly in practice for the region, because in this kind of projects in addition to precision that the designer must be done, input maps should also have high accuracy.