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Problem statement: In this study to evaluate the effects of hillside gradient on forest road cross section components in a loamy clay soil the amount of cut and fill slopes gradient and length, road bed and earthwork width were taken on tangent sections in a lat talar forest roads of Iran. Approach: The objective of this study were: (i) to evaluate the direct effects of hillside gradient on cross section components such as cut and fill slopes, road bed and earthwork width in a loamy clay soil, (ii) to use the model to predict the effect of hillside gradient on cross section components. Results: Results indicated that the regression analysis between hillside gradient and cut slope length had a significant linear relationship (p<0.0001), with equation of Y = 0.046+0.054 X (R² = 0.60). The equation for the calculation of earthwork width (Y) from hillside gradient was Y = 4.928+0.132 X (R² = 0.44). A significant linear relationship (p<0.0001), with equation of Y = 0.144- 2.638 (R2 = 0.64) was found between hillside gradient and fill slope length values. Conclusion: Through analysis of variance it was also found that the hillside gradient had a significant influence (p<0.0001) on the cross section components

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Effects of moisture, porosity and soil bulk density properties, grubbing time and terrain side slopes on pc 220 komatsu hydraulic excavator productivity were investigated in Miana forests road construction project which located in the northern forest of Iran. Soil moisture and porosity determined by samples were taken from undisturbed soil. The elements of daily works were measured with a digital stop watch and video camera in 14 observations (days). The road length and cross section profiles after each 20 m were selected to estimate earthworks volume. Results showed that the mean production rates for the pc 220 komatsu excavators were 60.13 m3 h(-1) and earthwork 14.76 m h(-1) when the mean depth of excavation or cutting was 4.27 m3 m(-1), respectively. There was no significant effects (p = 0.5288) from the slope classes' treatments on productivity, whereas grubbing time, soil moisture, bulk density and porosity had significantly affected on excavator earthworks volume (p < 0.0001). Clear difference was showed between the earthwork length by slope classes (p = 0.0060). Grubbing time (p = 0.2180), soil moisture (p = 0.1622), bulk density (p = 0.2490) and porosity (p = 0.2159) had no significant effect on the excavator earthworks length.

This study was conducted to investigate the interaction of soil properties and vegetation cover on soil loss from forest road prism. Rainfall simulations were carried out on road surface, fillslope and cutslope. Runoff and sediment samples were collected every 4 min and then total soil loss was measured. Samples from top soil were randomly collected for analysis and grouping soil into A, B and C. Results showed that on cutslope, the highest soil loss was detected for soil group B, where sediment concentration in runoff was 21.83 g L -1 and vegetation cover was 0 to 30%. On fillslope, the highest soil loss was detected for soil group C, where sediment concentration in runoff was 18.07 g L -1 and vegetation cover was 10 to 40%. On road surface, the highest soil loss was detected for soil group A, where sediment in runoff was 8.99 g L -1 and vegetation cover was 2 to 5%.