The main purpose of this study was evaluating indicators of forest road pavement degradation and their relation with different longitudinal slope classes after one year. Therefore, 30 plots of 100 m² (10×10 m) area at a distance of 100 meters from each other were selected by a systematic method in the study forest road in the north of Iran. All effective factors on pavement degradation, like longitudinal and transverse slope, crown canopy on top of plots, azimuth and shape of road

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... were measured. Additionally, to evaluate the mechanical characteristics of soil, 4 kg soil samples of pavement surface materials were taken from each mentioned plot. Regarding the results of average sifting through various sieves, we can state that in higher slope classes it is reduced by employing a bigger size of sieves. The percentage passing through sieve number 40 because of increasing slope in 4–7% slope classes was increased. There is a significant difference in the coefficient of uniformity between control treatment and classes 4–7% and above 7%. The treatments did not have an appropriate coefficient of curvature either. Totally, regarding negligible changes that were observed in class 4–7% in comparison with the other classes, we can figure out that this class is more suitable for the road construction.