## 4 Discussion
Since both criteria should be fulfilled, the most restrictive should be considered to correctly design an RPC;
* For a given value of \(h\), the slope decreases with increasing the vehicle speed;  
\[L_{a,1}=L_{e,1}=R_{vmin1}\ i/100=40\ i/100\ (\text{sag curves}) \tag{3}\]1 Schemes of RPCs longitudinal profiles—geometric criterion. \begin{table}
\begin{tabular}{c c c c c c c} \hline \hline \(h\) (cm) & \(i\) (\%) & \(L_{a}\) (m) & \(L_{A}\) (m) & \(L_{f}\) (m) & \(L_{e}\) (m) & \(L_{t}\) (m) \\ \hline
5 & 4.08 & 2.45 & 1.23 & 4.82 & 2.45 & 8.90 \\
10 & 5.77 & 3.46 & 1.73 & 5.15 & 3.46 & 10.93 \\
15 & 7.07 & 7.07 & 4.24 & 5.41 & 7.07 & 12.49 \\ \hline \hline \end{tabular}
\end{table} 
Table 5: Geometric characteristics of RPCs designed with a traffic-calming purpose criterion. * For a given value of \(v\), the slope increases with increasing value of \(h\). According to the calculated \(R_{\mathit{vmin}}\), Figure 18 shows the longitudinal profile of an RPC having \(v\) equal to 30 km/h and \(h\) equal to 15 cm. The results from the implementation of the proposed comfort criterion have been compared to each relieved RPC: For each surveyed site, Table 7 lists the effective and theoretical geometry of the RPCs. \begin{table}
\begin{tabular}{c c c c c c c c c} \hline \(v\) (km/h) & \(\mathbf{R_{\mathit{vmin}}}\) (m) & \(h\) (cm) & \(i\) (\%) & \(L_{a}\) (m) & \(L_{A}\) (m) & \(L_{f}\) (m) & \(L_{e}\) (m) & \(L_{t}\) (m) \\ \hline \multirow{3}{*}{20} & \multirow{3}{*}{51.44} & 5 & 3.12 & 3.21 & 1.60 & 5.60 & 3.21 & 10.41 \\  & & 10 & 4.41 & 4.54 & 2.27 & 6.27 & 4.54 & 13.07 \\  & & 15 & 5.40 & 5.56 & 2.78 & 6.78 & 5.56 & 15.11 \\ \hline \multirow{3}{*}{30} & \multirow{3}{*}{115.75} & 5 & 2.08 & 4.81 & 2.41 & 6.41 & 4.81 & 13.62 \\  & & 10 & 2.94 & 6.80 & 3.40 & 7.40 & 6.80 & 17.61 \\  & & 15 & 3.60 & 8.33 & 4.17 & 8.17 & 8.33 & 20.67 \\ \hline \multirow{3}{*}{40} & \multirow{3}{*}{205.75} & 5 & 1.56 & 6.41 & 3.21 & 7.21 & 3.21 & 16.83 \\  & & 10 & 2.20 & 9.07 & 4.54 & 8.54 & 4.54 & 22.14 \\  & & 15 & 2.70 & 11.11 & 5.56 & 9.56 & 5.56 & 26.22 \\ \hline \multirow{3}{*}{50} & \multirow{3}{*}{321.50} & 5 & 1.25 & 8.02 & 4.01 & 8.01 & 8.02 & 20.04 \\  & & 10 & 1.76 & 11.34 & 5.67 & 9.67 & 11.34 & 26.68 \\ \cline{1-1}  & & 15 & 2.16 & 13.89 & 6.94 & 10.64 & 13.89 & 31.78 \\ \hline \end{tabular}
\end{table} 
Table 6: Geometric characteristics of RPCs according to the comfort criterion. Figure 17: Schemes of RPCs longitudinal profiles—comfort criterion. Figure 18: Longitudinal profile of RPC having \(v\) = 30 km/h and \(h\) = 15 cm. According to the data in Table 8, more than 90% of the surveyed RPCs do not comply with the limits of the ramp longitudinal slope. Such conditions imply that ride comfort is not guaranteed, and the RPCs do not comply with the Italian geometric rules about road design. The last criterion, about the verification of the stopping sight distance, is always verified. Given the driver's eye height is equal to 1.10 m, and the object height equal to 0.10 m, the RPC (in the study it is not more than 15 cm high) does not obstruct the driver's line of sight. Therefore, only site 2 and site 3 (i.e., less than 9% of the overall surveyed RPCs) comply with the Italian geometrical and functional criteria to design roads (and pedestrian crossings). Finally, the second approach consists of a pedestrian crossing on a midblock traffic-calming device that raises the entire wheelbase of a vehicle to reduce its traffic speed. Therefore, an RPC joins two objectives: To have a raised feature, and to slow the speed of approaching vehicles. Under such conditions, RPCs also perform the tasks assigned to traffic-calming devices (e.g., speed tables, speed humps, or speed humps). Figure 19 represents a black and yellow speed table according to [49]: It is trapezoidal in shape with sharp edges of the inclined ramp.