Modeling the optimal density of forest roads for different scenarios based on average individual forest volume and vehicular load combinations

Abstract

Forest logistics processes account for over 50% of production costs, emphasizing the need to optimize these stages. Road network planning should follow optimization principles, particularly through the use of Optimal Road Density models. However, these models rarely consider vehicle load capacity and Average Tree Volume. This study aimed to determine the optimal forest road density under different scenarios combining average Individual Tree Volume and Vehicle Load Configurations. The study was conducted in Ribas do Rio Pardo, Mato Grosso do Sul, Brazil. The optimal road density was determined by minimizing the sum of operational costs, forest harvesting costs, road construction and maintenance costs, and the loss of productive area. The analysis considered various scenarios of average tree volume (0.15, 0.20, and 0.25 m³.tree⁻¹) associated with different vehicle configurations (bitrem, tritrem, and hexatrem). Operational costs were estimated based on mechanized forest harvesting, while road costs were calculated as the sum of pavement construction and maintenance expenses. The costs related to the loss of productive area were derived from the value of the land occupied by roads and the estimated revenue from the effective use of the area. The variation in optimal road density across the evaluated scenarios ranged from 19.57 to 27.61 m·ha⁻¹, corresponding to the lowest average volume of 0.15 m³.tree⁻¹ (hexatrem) and the highest of 0.25 m³.tree⁻¹ (bitrem). For the 0.15 m³.tree⁻¹ volume scenario, the optimal densities were 25.57 and 23.68 m·ha⁻¹ for bitrem and tritrem, respectively. For the 0.20 m³.tree⁻¹ scenario, the values were 26.16, 24.46, and 20.45 m·ha⁻¹ for bitrem, tritrem, and hexatrem, respectively. Finally, for the 0.25 m³.tree⁻¹ scenario, the optimal densities were 26.91 and 22.06 m·ha⁻¹ for tritrem and hexatrem, respectively. We concluded that the Optimal Road Density varies according to the Individual Average Volume of trees and the Vehicle Load Capacity. Lower Individual Average Volumes combined with higher-capacity vehicles resulted in lower Optimal Road Density values.