Planning road networks in landslide-prone areas: A case study from the northern forests of Iran

•Illustrating an important application of landslide susceptibility (LS) maps.•Evaluating road alternatives using a LS map, and a cost estimation model.•Demonstrating the influence of LS on planning and locating forest roads.•Identifying the alternative that meets environmental and economic goals.•Providing insights into trade-offs among policies with conflicting goals. Road development in mountainous forestlands can lead to naturally formed slopes being disturbed. Efficient planning methodologies can assist forest engineers in either preventing or reducing the environmental impacts of forest roads. In this study, we first prepared an inclusive landslide susceptibility map for our study area using a Bayesian model. We next designed 12 road network alternatives using PEGGER, an ArcView GIS extension. We extracted the values of these alternatives from the susceptibility map to evaluate their environmental feasibility. We also evaluated the alternatives from an economic perspective using a model for conducting cost estimates of the forest roads. Our results show that this approach is useful for identifying the alternative that meets environmental and economic goals. The policy implications of this study suggest that if the development of road networks in mountainous areas is an important forestry goal, mechanisms should be aimed primarily at controlling slope instability.