# Median U-Turn Intersection Critical Parameter Research and Operational Performance Evaluation
## 5 Model Effectiveness Validation
### Simulation Construction  
To examine the reliability of the proposed cellular automata model, we will employ commercial simulation software VISSIM (Version 4.0) to construct a traffic simulation model based on a realistic traffic scenario. As a leading simulation software, VISSIM can present a vehicle operation environment under different conditions, such as lane type, traffic composition, and traffic signal control [47; 48]. Because of the similar operating rules, the VISSIM model can serve as a comparison for the proposed cellular automata model. Subsequently, we compare the average vehicle delay simulated by the two models to demonstrate the consistency between the cellular automaton model and the microsimulation model in different scenarios. Therefore, the VISSIM model based on the current situation of the selected MUT intersection is built first. Then, based on the calculation results in Chapter 3, the modified VISSIM model for the selected MUT intersection is also constructed. The modified parameters of the MUT intersection are presented in Table 5.  
The VISSIM model for the current MUT intersection is built using the parameters obtained from the field. According to Table 5, the VISSIM model for the modified MUT intersection is also developed. It should be noted that the east and west sides of the modified MUT intersection model each require an exclusive separation distance. According to Equation (8), the appropriate separation distance, L, for the selected intersection is slightly greater than the calculated value. Therefore, the separation distance on the west side of the intersection is 92 m, and the separation distance on the east side of the intersection is 124 m.  
Similarly, the gap and width of the median U-turn should be considered to use an identical method. Therefore, based on Table 5, the gap and width of the median U-turn \begin{table}
\begin{tabular}{c c c c c c c} \hline \hline  & & **Day 1** & **Day 2** & **Day 3** & **Day 4** & **Day 5** \\ \cline{3-6}
**Direction** & & **Traffic Flow** & **Traffic Flow** & **Traffic Flow** & **Traffic Flow** & **Traffic Flow** \\  & & **(veh/h)** & **(veh/h)** & **(veh/h)** & **(veh/h)** & **(veh/h)** \\ \hline \multirow{3}{*}{East entrance} & Left turn & 176 & 167 & 157 & 169 & 164 \\  & Straight through & 733 & 766 & 735 & 746 & 772 \\  & Right turn & 147 & 123 & 139 & 143 & 151 \\ \hline \multirow{3}{*}{West entrance} & Left turn & 182 & 190 & 187 & 174 & 193 \\  & Straight through & 774 & 765 & 721 & 760 & 780 \\  & Right turn & 158 & 163 & 142 & 161 & 160 \\ \hline \multirow{3}{*}{South entrance} & Left turn & 105 & 119 & 106 & 103 & 112 \\  & Straight through & 159 & 147 & 135 & 137 & 149 \\  & Right turn & 32 & 46 & 41 & 39 & 47 \\ \hline \multirow{3}{*}{North entrance} & Left turn & 96 & 85 & 83 & 91 & 90 \\  & Straight through & 162 & 152 & 138 & 166 & 157 \\ \cline{1-1}  & Right turn & 43 & 55 & 39 & 47 & 51 \\ \hline \multicolumn{2}{c}{Total (veh/h)} & 2767 & 2778 & 2623 & 2736 & 2826 \\ \hline \hline \end{tabular}
\end{table} 
Table 4: Traffic data at the entrance of the selected MUT intersection during peak hours. are 8 m and 10 m, respectively. Additionally, the signal cycle of both VISSIM models is consistent with that of the selected intersection. All the parameters required for building the simulation models have been obtained. In this paper, the cellular automata models are simulated using MATLAB. We will provide two versions of the cellular automata model separately: one with the current parameters and the other with modified parameters. The total lengths of the major road on the east and west sides of the selected intersection are 150 cells and 100 cells, respectively. The total length of the minor road on the north and south sides of the selected intersection is 120 cells. One vehicle occupies one cell, and the length of each cell is 4 m. No central boundary line is placed at specific locations of certain cells on the major road to simulate median U-turn operations.