## 4 Study Results
### Uniform Speed-Limit (USL) Results
#### 4.1.2 Simulated Safety Results  
Tables 6-10 show the conflict ratio (\(\rho\)) for the total simulated conflicts for time to collisions (TTC) of \(\leq\)2.5, \(\leq\)1.50, and \(\leq\)0.50 s and for speed limits of 50, 60, 70, 80, and 90 km/h, respectively, for the USL strategy. It is worth noting that, if \(\rho>1.0\), then the 2+1 design would increase the number of simulated conflicts and, hence, the number of crashes compared to the TLTW design, while a value of \(\rho<1.0\) indicates that the 2+1 design would reduce the number of simulated conflicts and, therefore, reduce the number of crashes compared to the TLTW design. And if \(\rho=1.0\), then the 2+1 design is not different from the TLTW design, and hence, there is no safety gain or loss. \begin{table}
\begin{tabular}{c c c c c c c c} \hline \hline \multirow{2}{*}{**V**} & \multirow{2}{*}{**\%HV**} & \multicolumn{4}{c}{**TLTW to 2+1 (No Pass)**} & \multicolumn{4}{c}{**TLTW to 2+1 (Allow Pass)**} \\ \cline{3-8}  & & & **TTC \(\leq\) 2.50** & **TTC \(\leq\) 1.50** & **TTC \(\leq\) 0.50** & **TTC \(\leq\) 2.50** & **TTC \(\leq\) 1.50** & **TTC \(\leq\) 0.50** \\ \hline  
52 (0.10) & **0.89 (0.11)** & 0.09 (0.02) & _1.73 (0.11)_ & _1.80 (0.20)_ & _1.52 (0.20)_ \\ \hline \hline \end{tabular}
\end{table} 
Table 6: Conflict ratio, with standard error between conventional TLTW before and after 2+1 design for network speed of 50 km/h for USL Strategy. \begin{table}
\begin{tabular}{c c c c c c c c} \hline \hline \multirow{2}{*}{**V**} & \multirow{2}{*}{**\%HV**} & \multicolumn{4}{c}{**TLTW to 2+1 (No Pass)**} & \multicolumn{4}{c}{**TLTW to 2+1 (Allow Pass)**} \\ \cline{3-8}  & & & **TTC \(\leq\) 2.50** & **TTC \(\leq\) 1.50** & **TTC \(\leq\) 0.50** & **TTC \(\leq\) 2.50** & **TTC \(\leq\) 1.50** & **TTC \(\leq\) 0.50** \\ \hline
250 & & 0.19 (0.07) & 0.02 (0.02) & 0.00 (0.00) & 2.76 (0.64) & 2.94 (0.69) & 3.23 (0.92) \\
500 & & 0.37 (0.05) & 0.04 (0.02) & 0.02 (0.01) & 2.93 (0.37) & 3.61 (0.48) & 3.99 (0.67) \\
750 & 2.5 &  
It is worth noting that the total conflicts in the current analysis were selected, as most of conflicts in the TLTW design are head-on conflicts (i.e., vehicles would collide with each other's front bumper to front bumper), while in the 2+1 design with prohibited overtaking in the opposite direction, all conflicts are rear-end (the front bumper of the rear vehicle could collide with the rear bumper of the lead vehicle), which are different types of conflicts. \begin{table}
\begin{tabular}{c c c c c c c} \hline \hline
**V** & **\%HV** & \multicolumn{3}{c}{**TLTW to 2+1 (No Pass)**} & \multicolumn{3}{c}{**TLTW to 2+1 (Allow Pass)**} \\ \cline{3-7}  & & **TTC \(\leq\) 2.50** & **TTC \(\leq\) 1.50** & **TTC \(\leq\) 0.50** & **TTC \(\leq\) 2.50** & **TTC \(\leq\) 1.50** & **TTC \(\leq\) 0.50** \\ \hline
250 & & 0.29 (0.07) & 0.00 (0.00) & 0.00 (0.00) & 3.33 (0.62) & 3.58 (0.60) & 4.19 (1.05) \\
500 & & 0.38 (0.07) & 0.05 (0.02) & 0.01 (0.01) & 2.55 (0.40) & 2.91 (0.48) & 3.32 (0.62) \\
750 & 10 & 0.77 (0.10) & 0.14 (0.03) & 0.06 (0.02) & 1.97 (0.24) & 2.13 (0.25) & 2.38 (0.31) \\
1000 & & 1.42 (0.11) & 0.26 (0.03) & 0.07 (0.01) & 2.01 (0.16) & 1.57 (0.13) & 1.61 (0.14) \\
1250 & & 2.03 (0.18) & 0.53 (0.08) & 0.07 (0.01) & 2.38 (0.21) & 1.47 (0.21) & **1.22 (0.21)** \\ \hline
250 & & 0.29 (0.12) & 0.00 (0.00) & 0.00 (0.00) & 4.05 (0.95) & 4.11 (0.4) & 4.22 (1.26) \\
500 & & 0.44 (0.08) & 0.06 (0.02) & 0.02 (0.02) & 3.18 (0.52) & 3.51 (0.59) & 4.07 (0.77) \\
750 & 15 & 0.75 (0.08) & 0.18 (0.03) & 0.04 (0.01) & 1.85 (0.17) & 1.89 (0.20) & 2.22 (0.24) \\
1000 & & 1.47 (0.14) & 0.29 (0.04) & 0.05 (0.02) & 2.06 (0.20) & 1.46 (0.19) & **1.38 (0.21)** \\
1250 & & 2.32 (0.16) & 0.72 (0.09) & 0.08 (0.02) & 2.67 (0.19) & 1.87 (0.21) & **1.34 (0.23)** \\ \hline \hline \end{tabular}
\end{table} 
Table 7: _Cont._