## 4 Study Results  
### Uniform Speed-Limit (USL) Results  
#### 4.1.1 Simulated Mobility Results  
Figure 3 shows the average network delay (second/vehicle) for the three design alternatives (i.e., TLTW, 2+1 that prohibits overtaking in the opposite direction, and 2+1 that allows overtaking in the opposite direction) using the USL strategy with speed limits of 50, 60, 70, 80, and 90 km/h for different traffic volumes and different percentages of HVs. It is obvious that the percentage of HVs does not have an effect at all on the average delay. There are slight delay differences for traffic volumes of around 1250 vehicles per hour, but all the differences are not statistically significant at the five percent level of significance. \begin{table}
\begin{tabular}{l c c} \hline \hline
**Parameter** & **1 st Direction** & **2 nd Direction** \\ \hline Average travel speed \(\pm\) standard & & \\ deviation (meter/second) & & \\ \hline Number of successful overtakes & & \\ \hline \hline \end{tabular} Values between parentheses represent the relative difference between the simulated and the observed values.  
\end{table} 
Table 4: _Cont._  
Figure 3: Average network delay (second/vehicle) for uniform speed-limit scenarios: (**a**) speed limit = 50 km/h, (**b**) speed limit = 60 km/h, (**c**) speed limit = 70 km/h, (**d**) speed limit = 80 km/h, and (**e**) speed limit = 90 km/h. In addition, both of the 2+1 designs are expected to significantly reduce the average delay compared to the conventional TLTW design for all traffic volumes and all tested speed limits. Those changes are all statistically significant at the five percent level of significance. Furthermore, the 2+1 design that allows overtaking in the opposite directions results in a higher reduction in the average delay compared to the 2+1 design that prohibits overtaking in the opposite direction. The differences in delay between the 2+1 designs are negligible for higher speed limits and higher traffic volumes, as shown in Figure 3.  
Similarly, Figure 4 shows the average travel speed (ATS) results for the USL strategy. It shows concise results that are similar to the average delay results, in that the %HVs has no effect and the ATS increases significantly for the two 2+1 designs compared to the conventional TLTW design, and there is a negligible difference in travel speed between the 2+1 designs for higher speed limits and higher traffic volumes. Table 5 shows the results of the USL strategy for different speed limits and different traffic volumes at 2.5% HVs. For both 2+1 designs, there are statistically significant improvements, at the 5% significance level, in both ATS (i.e., increase) and delay (i.e., decrease) for different traffic volumes and different speed limits compared to the TLTW design. The improvements in ATS were between 1.4% (at low traffic volume) and 12.5% (at volume  
Figure 4: Average travel speed (km/h) for uniform speed-limit scenarios: (**a**) speed limit = 50 km/h, (**b**) speed limit = 60 km/h, (**c**) speed limit = 70 km/h, (**d**) speed limit = 80 km/h, and (**e**) speed limit = 90 km/h. near capacity) and between 3.3% and 13.80% for the 2+1 design that prohibits overtaking in the opposite direction and the one that allows it, respectively. In addition, the reduction in average delay varies from 26% to 50% and from 47% to 74% for the 2+1 design that prohibits overtaking and the one that allows it, respectively.