# A Review of Road Design for Wind Farms in China
## 4 Research on Profile Design  
[PERSON] [26] used Latitude 3D road design software based on a 3D ground model and real-time drag technology to dynamically and interactively complete the horizontal, vertical, and cross-section design of the road route on the computer. By using the Latitude 3D road auxiliary system for the second phase project of the Jinzishan Wind Farm, the work efficiency was greatly improved. [PERSON] [27] analyzed the harm of the wind power plant road caused by sand activities and expounded the route selection ideas and design points of the wind power plant road in the desert area combined with the actual project. In order to reduce the influence of sand buried on the road of the wind power plant, the longitudinal section design of the route should adopt the appropriate height embankment scheme. [PERSON] [28] and others established the templates required by roads in the project through the template design function of power civil in the design of alpine wind power sites with complex terrain conditions. They generated various roads according to the project terrain. In the cross-section template library, they generated the road model for verification according to the design needs, making the road modeling more efficient, avoiding dangerous sections, and helping to promote the application of the three-dimensional model of roads in the wind farm site. The cabin of large equipment of the wind turbine generator is the heaviest, so the maximum gradient of the road should be based on the climbing capacity of transport vehicles. According to the requirements of the transport manual of wind turbine generator manufacturers and in combination with the construction experience of wind farms in China for many years, the method for determining the maximum longitudinal gradient is summarized by [PERSON] [18], and it is concluded that the maximum longitudinal gradient of the road is 14%, which can meet the transport requirements of the wind turbine generator. Generally speaking, in areas with relatively good conditions, the average longitudinal slope of wind farm roads should not be greater than 5.5%. When the longitudinal slope of the road is continuously greater than 5%, a gentle slope section shall be set. The gradient of the gentle slope section shall not be greater than 3% and the length shall not be less than 50 m.  
Through the analysis of the wind farm fan equipment and the domestic fan transport models, aiming at the traction force on the driving shaft and the calculation of driving resistance, [PERSON] [29] and [PERSON] [30] presented the calculation formula of the traction force on the driving shaft and the driving resistance of the vehicle, as shown \begin{table}
\begin{tabular}{c} **No Widening** \\ **Minimum Radius** \\ \end{tabular} \\ \hline
750 kW & 15 & 60 & 15 & 45 \\
1500 kW & 25 & 110 & 20 & 85 \\
2500 kW & 35 & 135 & 30 & 110 \\ \hline \hline \end{tabular}
\end{table} 
Table 2: Minimum radius with a widening limit of 10 m [14]. in (14) to (19). In combination with the driving balance equation of the vehicle, the maximum climbing slope value of the engine room transport vehicle is calculated, and the calculation formulas for the maximum gradient angle and the maximum gradient of transport vehicles are shown in (13). Through the calculation of road transport of wind farms with three types of wind turbines commonly used in China at different altitudes, the maximum gradient of the typical models used are calculated, respectively, and the design value of the maximum longitudinal gradient of wind farm roads for designers' reference is obtained (Table 3). \[\left\{ \begin{array}{l c c c c c}a_{\text{Imax}}=\arcsin\frac{\lambda D_{\text{ Imax}}-f\sqrt{1-\lambda^{2}D_{\text{Imax}}^{2}+f^{2}}}{1+f^{2}}\\ i_{\text{max}}=\tan a_{\text{Imax}}\end{array} \right.