# Vehicle Delay Model Applied to Dynamic and Static Traffic Impact Analysis of Large Parking Lots
## 4 Analysis of Simulation Experiment  
### Establishment of Simulation Model  
Jingfeng parking lot in Nanjing mainly serves the parking demand of Jingfeng commercial plaza. There are three floors in the parking lot, namely B1, B2, and B3. Its total number of berths is 1800. The interaction between dynamic and static traffic is quite intense. There are two entrances and exits in the parking lot. The entrance and exit on the east side are connected to the branch with two lanes on the same side. It belongs to the entrance and exit of the atypical parking lot. The road connecting the west entrance and exit is three lanes on the same side, and the entrance and exit are 155 m away from the downstream T-shaped intersection. There are few conflict points at the intersection, and there is no traffic control, and the traffic capacity of the road is high. It can be concluded that the entrance and exit of the West parking lot are suitable for dynamic and static traffic impact analysis. Therefore, this paper selected the west entrance as the research object. (1) Obtain the basic data required for simulation scene modeling  
After pre-investigation, it was found that the peak time is 17:00-19:00. The video survey method and manual survey method were used to obtain the data such as the entrance, the geometric size of the road and the proportion of vehicles entering the parking lot in each lane, so as to provide data support for the simulation scene. The traffic flow entering the parking lot and the traffic flow of the branch road were counted at an interval of 15 min. The statistical results were shown in Table A1 in Appendix A. It can be seen that the proportion of vehicles arriving at the parking lot to the number of road vehicles fluctuates around 20%;  
Similarly, conduct a traffic volume survey on the connecting road of the west exit. The statistical results were shown in Table A2 in Appendix B. The results showed that the path ratio from the second lane to the parking lot was 1:1. In addition, only a few vehicles entered from the third lane, which was negligible compared with the number of vehicles entering from the other two lanes. (2) Construct the VISSIM simulation scene of the Jingfeng parking lot  
Input the road network scene, the attributes of the road section, entrances and exits, deceleration zone and other parameters in VISSIM simulation software. (3) Correct the parameters of the VISSIM simulation software  
This paper used the headway index [24] to correct the parameters of the car-following model, so that the simulation experiment was closer to the actual situation. The iterative process was shown in Figure 4. After 11 iterations, the objective function suddenly decreased and then tended to be flat, indicating that the value of the objective function at this time gradually approaches the optimal solution after updated calculation and met the convergence conditions. The final objective function value is 0.1467 s. The average headway obtained from the experiment was 5.2652 s. Since the measured headway was 5.4119 s, the relative error can be calculated as 2.71%. The error is within the control range, which means that the optimal solution was obtained. Figure 4: Iterative process and error value. Therefore, the three parameters of the car-following model in VISSIM were modified. The average parking distance was changed to 1.8654m. The additional part of the safety distance was changed to 1.5643. The multiple of safety distance was changed to 2.5795. (4) Set parameter information such as conflict area, stop signal, signal lamp and travel time detector. The built simulation environment is shown in Figure 5.  
(5) Run the simulation model and conduct batch simulation  
Input the traffic volume of different combinations according to the traffic volume of investigation and statistics. Enter the number of vehicles from 200 to 2100 vehicles/h in the road traffic volume, and increase the traffic flow with an interval of 100 vehicles/h. It was a total of 20 traffic flows.