# Speed Reduction Capabilities of Two-Geometry Roundabouts
## 3 Results
### Roundabout Schemes with Fixed (y)
The modeled simple linear dependency of the distance between the tangent of the entry radius and the tangent of the exit radius along the major axis (L), the distance between the tangent of the entry radius and the tangent of the exit radius along the minor axis (L\({}^{\prime}\)), the deflection along the major axis (U), and the deflection along the minor axis (U\({}^{\prime}\)) and the major axis length (a) for roundabout schemes with fixed (y) is shown in Figures 9 and 10. It can be noted that compared to the roundabout schemes with variable (y), the parameters (L) and (L\({}^{\prime}\)) remained the same and that parameters (U) and (U\({}^{\prime}\)) were slightly larger. Their dependency on (a) remained the same. The calculated vehicle path radius (R) and measured personal vehicle fastest paths radii Ri and R\({}^{\prime}\)\({}_{\rm i}\) (i = 1-3) for the variable circulatory roadway width along the minor axis (y) are given in Appendix A, Table A3. The modeled simple linear dependency of the personal vehicles' fastest path radii (R\({}_{\rm i}\) and R\({}^{\prime}\)\({}_{\rm i}\), where i = 1-3) and the major axis length (a) is shown in Figures 11-13 for roundabout schemes with fixed (y). It can be noted that compared to the roundabout schemes with variable (y), these radii were smaller. Radii for (b/a = 0.75) showed the greatest discrepancy, caused by large path radii values at roundabou \begin{table}
\begin{tabular}{c c c c c c c c c c} \hline \hline \multirow{2}{*}{**a (m)**} & \multicolumn{2}{c}{**b/a = 0.75**} & \multicolumn{2}{c}{**b/a = 0.80**} & \multicolumn{2}{c}{**b/a = 0.85**} & \multicolumn{2}{c}{**b/a = 0.90**} & \multicolumn{2}{c}{**b/a = 1.00**} \\  & **L\({}^{\prime}\) (m)** & **U\({}^{\prime}\) (m)** & **L\({}^{\prime}\) (m)** & **U\({}^{\prime}\) (m)** & **L\({}^{\prime}\) (m)** & **U\({}^{\prime}\) (m)** & **L\({}^{\prime}\) (m)** & **U\({}^{\prime}\) (m)** & **L\({}^{\prime}\) (m)** & **U\({}^{\prime}\) (m)** \\ \hline
18 & 51.48 & 3.55 & 50.41 & 4.36 & 55.53 & 5.37 & 57.74 & 6.29 & 64.63 & 8.20 \\
19 & 51.92 & 4.27 & 52.98 & 5.19 & 56.66 & 6.20 & 63.51 & 7.32 & 69.66 & 9.30 \\
20 & 53.21 & 50.1 & 58.71 & 6.13 & 59.97 & 7.11 & 63.70 & 8.17 & 71.44 & 10.30 \\
21 & 54.93 & 5.92 & 58.66 & 6.88 & 62.14 & 7.97 & 63.86 & 8.99 & 75.60 & 11.37 \\
22 & 59.62 & 6.63 & 62.82 & 7.76 & 66.17 & 8.90 & 71.22 & 10.10 & 79.15 & 12.42 \\
23 & 59.92 & 7.07 & 64.85 & 8.58 & 68.39 & 9.77 & 73.38 & 11.01 & 83.36 & 13.55 \\
24 & 63.19 & 8.15 & 69.24 & 9.47 & 72.44 & 10.70 & 80.40 & 12.09 & 87.44 & 14.62 \\
25 & 65.05 & 8.91 & 69.34 & 10.22 & 76.86 & 11.64 & 81.57 & 13.02 & 91.66 & 15.79 \\ \hline \hline \end{tabular}
\end{table} 
Table 7: Distances between the tangent of the entry radius and the tangent of the exit radius along the minor axis (L\({}^{\prime}\)) and deflections along the minor axis (U\({}^{\prime}\)) for roundabout schemes with fixed (y). Figure 9: The linear dependency of the distance between the tangent of the entry radius and the tangent of the exit radius (L and L\({}^{\prime}\)) and the major axis length (a) for roundabout schemes with fixed (y). Figure 11: The linear dependency of the entry path radii (R\({}_{1}\) and R\({}^{\prime}\)\({}_{1}\)) and the major axis length (a) for roundabout schemes with fixed (y). Figure 12: The linear dependency of the circulating path radii (R\({}_{2}\) and R\({}^{\prime}\)\({}_{2}\)) and the major axis length (a) for roundabout schemes with fixed (y). Figure 10: The linear dependency of the deflection (U and U\({}^{\prime}\)) and the major axis length (a) for roundabout schemes with fixed (y). Analyses of the vehicle path deflection around the central island have shown that **Condition 3 (D > 7.00.m)** was not met by one analyzed two-geometry roundabout (Appendix A, Table A4): the one with a major axis (a) of 18 m and (b/a = 0.75) for both directions. This condition was met by all analyzed standard roundabout schemes with fixed (y).