Background and Objectives: Forest roads are critical infrastructure for forest management, conservation, and access. During periods when forest management activities and timber harvesting are suspended, the maintenance of existing roads may decline. However, a road's condition is not solely dependent on the cessation of harvesting; factors such as longitudinal slope, drainage, road geometry, soil properties, rainfall, road age, initial construction quality, and traffic also contribute to its deterioration. Therefore, this study aimed to descriptively compare quantitative and qualitative indicators of road condition across two longitudinal slope classes (>7% and <5%) on a secondary forest road within the Kelardasht Forestry Plan, located in the Hyrcanian forests. The primary objective was to evaluate the effect of slope magnitude on the degradation and deterioration of forest road pavement during a logging-ban period.
Materials and Methods: Eight road segments were investigated, each situated between two consecutive cross culverts. Four segments were in the less than 5% slope class, and four were in the greater than 7% slope class. Field data collected included the longitudinal slope of each segment and the condition of culverts, side ditches, road surface, and cut-and-fill slopes. Quantitative variables for each class were summarized using the arithmetic mean, while categorical variables were reported descriptively.
Results: In segments with a slope greater than 7%, a higher frequency of road surface degradation indicators, culvert blockage, side ditch malfunction, and cut slope instability was observed. The mean longitudinal slope was 7.75% in the greater than 7% class and 2% in the less than 5% class. The mean cross slope was 4.75% and 2.5%, respectively. Signs of erosion were observed below the culvert outlet in all segments of both classes. Culverts on slopes greater than 7%, along with cut slopes, had a more significant impact on erosion and side ditch blockage, consequently increasing runoff on the road surface, which led to the formation of potholes and the loss of surfacing material.
Conclusion: While signs of road degradation were observed in both slope classes, the frequency of certain degradation indicators was higher in segments with slopes greater than 7%. These results highlight the necessity of regular monitoring and maintenance of culverts, side ditches, road surfaces, and cut-and-fill slopes. Adequate and urgent budget allocation for the maintenance and repair of existing roads is essential. This study's novelty lies in its integrated recording of indicators for road surface, drainage, culverts, and cut-and-fill slopes across defined longitudinal slope classes. The resulting checklist can serve as a practical basis for subsequent monitoring and for identifying segments in need of repair and maintenance.
