## 3 Results
The results of the calculation of the entry degree of saturation with dependence on the \(\rm R_{o}\) of roundabouts and \(\rm\delta\) according to the analytical model (\(\rm x_{mj,A}\)) and regression model (\(\rm x_{mj,R}\)) showed that \(\rm x_{mj}\) values were inversely proportional to \(\rm R_{o}\). \(\rm x_{mj,R}\) values followed the observed trend of \(\rm b_{j}\) for all analyzed \(\rm\delta\) at each roundabout leg (Figures 9b, 10, 11 and 12b). For \(\rm R_{o}\leq 16.5\) m, an established trend showed a more rapid decrease in \(\rm b_{j}\) and, consequently, in \(\rm x_{mj,R}\). On the other hand, for \(\rm R_{o}\geq 19.0\) m, it can be stated that the differences in the right roadway edge design, regardless of \(\rm\delta\), do not affect \(\rm x_{mj,R}\). The values of \(\rm x_{mj,A}\) decreased at a lower and uniform rate as \(\rm R_{o}\) increased. \(\rm x_{mj,A}\) values were higher than \(\rm x_{mj,R}\) by, on average, 16%. The average difference between \(\rm x_{mj,A}\) and \(\rm x_{mj,R}\) varied between 0.088 and 0.100. These extreme differences were observed for \(\rm\delta=75^{\circ}\), at leg 1 and leg 2, respectively. At each leg, the average observed difference between the calculated \(\rm x_{mj,R}\) for \(\rm\delta=90^{\circ}\) and \(\rm x_{mj,R}\) for the  
Figure 11: Investigated parameters at leg 3 as a function of \(\rm R_{o}\) for different \(\rm\delta\), considering the application of design conditions 1 and 2: (**a**) geometric parameter \(\rm b_{3}\); (**b**) traffic parameter \(\rm x_{mj,3}\). Figure 12: Investigated parameters at leg 4 as a function of \(\rm R_{o}\) for different \(\rm\delta\), considering the application of design conditions 1 and 2: (**a**) geometric parameter \(\rm b_{4}\); (**b**) traffic parameter \(\rm x_{m4}\). other \(\delta\) values amounted to (1) 0.3% at leg 2 for \(\delta\) = 85\({}^{\circ}\), (2) 1.1% at leg 1, and 0.4% at leg 2 for \(\delta\) = 80\({}^{\circ}\), (3) 1.7% at leg 1, 0.5% at leg 2, and 0.2% at leg 3 for \(\delta\) = 75\({}^{\circ}\). Figure 13 shows the average difference between b\({}_{1}\), b\({}_{2}\), and b\({}_{3}\) for \(\delta\) = 90\({}^{\circ}\) and b\({}_{1}\), b\({}_{2}\), and b\({}_{3}\) for \(\delta\) = 85\({}^{\circ}\), 80\({}^{\circ}\), and 75\({}^{\circ}\), respectively. The change in these differences in b\({}_{1}\) values is linear. As expected, b\({}_{1}\) shortened as \(\delta\) decreased. The opposite is true for b\({}_{2}\) and b\({}_{3}\). The main reason for this is the design of the right roadway edge based on the design vehicle swept path analysis. Namely, on the roundabout exit at legs 2 and 3, the body of the design vehicle swept a wider surface than on the roundabout entry at leg 1, and this surface was ever wider as \(\delta\) decreased. Therefore, the designed exit radii R\({}_{2}\)\({}^{\prime}\) and R\({}_{3}\)\({}^{\prime}\) were significantly larger than the recommended ones and, consequently, the distances b\({}_{2}\) and b\({}_{3}\) were inversely proportional to \(\delta\). The results of the reversed calculation of traffic flow at each leg according to the regression model methodology showed that, at a given roundabout, the application of the regression model gives the same x\({}_{\rm mj}\) results as the analytical one for 6% to 15% higher traffic flows q\({}_{i}\). The difference in traffic flow values obtained through this calculation is shown as a percentage concerning the initial total value of 1800 veh/h (Figure 14). Figure 14: Results of the reversed calculation of traffic flow—the difference in traffic flow values shown as the percentage of the initial 1800 veh/h.