## 5 Experimental Results and Analysis
### Over-the-Horizon PTV Perception Algorithm  
#### 5.4.1 Over-the-Horizon Perception Range Division  
In order to provide more timely road information and improve the traffic safety of travelers, it is necessary to provide timely information about road conditions and PTV driving on the road. The traffic speed of the vehicle is calculated by the vehicle information obtained from the ETC gantry, so as to determine the section where the vehicle is located. After determining the section where the vehicle is located, the PTV over-the-horizon \begin{table}
\begin{tabular}{c c c c c c c c c} \hline \hline
**License Plate** & **OS** & \(\mu_{\text{OS}}\) & **VT** & \(\mu_{\text{VT}}\) & **LD** & \(\mu_{\text{LD}}\) & **VF** & \(\mu_{\text{TF}}\) & **DTS** \\ \hline HuangHu***** & 82.12 km/h & 0.39 & 16 & 1 & 5.42 h & 0.11 & 1798 & 1 & 50.2 \\ HuangWan***** & 96.65 km/h & 0.63 & 14 & 1 & 4.65 h & 0.023 & 1798 & 1 & 60.29 \\ LvMin***** & 144.17 km/h & 0.99 & 1 & 0.056 & 5.1 h & 0.067 & 1761 & 1 & 63.84 \\ LanMin***** & 139.84 km/h & 1 & 1 & 0.056 & 6.9 h & 0.47 & 1761 & 1 & 73.01 \\ Huanglin***** & 3 & 137.75 km/h & 1 & 15 & 1 & 4.21 h & 0.0024 & 1673 & 1 & 78.65 \\ \hline \hline \end{tabular}
\end{table} 
Table 16: PTV example. \begin{table}
\begin{tabular}{c c} \hline \hline
**Model Index** & **Result** \\ \hline Accuracy & 98.03\% \\ Recall & 99.55\% \\ \hline \hline \end{tabular}
\end{table} 
Table 14: Algorithm result display. distance (safety distance) can be further detected. The selection of safe distance must meet the best safe time and space for warning the driver to avoid danger, so as to remind the driver to control their speed at the first opportunity and in a timely manner. Therefore, the early and late warning of PTVs beyond the sight distance is not conducive to the coordinated response of drivers, and the effectiveness of the safety warning is lost. The statistical analysis of all vehicle speeds in some sections is carried out by using a box diagram, and the summary of data results is shown in Table 17.  
Observing Table 17, it is found that the maximum speed of the vehicle reaches 136.21 km/h, while the minimum speed of the section is only 60.63 km/h; the speed difference between the two is 75.49 km/h. Because of this, we analyze the speed difference from 10 km/h to 80 km/h, and the time when they can meet at different vehicle distances. The results are shown in Table 18.  
Take the maximum speed difference as an example. When the speed difference is 80 km/h, and the distance between the two vehicles is 1 km, it only takes 45 s for the two vehicles to meet. If the warning time is too late, the driver will not be able to respond in time, and the 1 km warning distance is too short. If driving in a straight road section, the driver can observe the road conditions well and make cooperative responses. When the distance is 6 km, it takes 4.5 min for two cars to meet, which is enough time for travelers to make decisions in advance. Therefore, we select 2 km as the safety warning distance, and use 4 km and 6 km as the auxiliary safety warning distance to allow drivers to perceive the over-the-horizon road conditions in advance. However, different vehicle types have different traffic speeds on the same road, and this paper selects the vehicle traffic data of the section from gantry 340241 to 340243 on 1 May 2021, and analyzes the average traffic speed of different types of vehicles. The results are shown in Figure 13, which shows that there are certain differences in the average traffic speed of different vehicle types. Among them, the average traffic speed of Class I passenger cars is significantly greater than other types of vehicles, reaching about 110 km/h. The average speed of other types of passenger cars is about 90 km/h. The average speed of trucks and special operation vehicles is generally about 80 km/h. Therefore, through the fine division of vehicle types, the potential dangerous vehicles can be effectively evaluated.