## 4 Discussion
### Analysis of Time-Varying Characteristics of Glare in the Access Zone of West Oriented Tunnel
As can be seen from Figure 18, from 10:00 a.m. to 12:00 a.m., \(PGSV\) glare values of Longquanshan No. 1 Tunnel were 2.3515, 2.3831, and 2.6262, respectively, which exceeded the uncomfortable glare limits. The corresponding luminance difference between inside and outside the tunnel is 90%, 91%, and 92.2%, respectively. According to the \(PGSV\) glare value of the daylight model, the \(PGSV\) glare value after rain is greater than the \(PGSV\) glare value at the maximum luminance outside the tunnel (14:00 p.m.). It is not difficult to find that the glare effect after rainfall is very serious in the field of view of 20\({}^{\circ}\) luminance outside the tunnel. At 16:00, the \(PGSV\) glare value of the near section of Longquanshan No. 1 tunnel was 7.1017, far exceeding the unbearable glare limit. The corresponding difference of luminance contribution ratio outside the hole was as high as 94%. The \(PGSV\) for the road and surroundings after rainfall reached 3.0987 and 4.003, respectively, both exceeding the threshold of intolerable glare for drivers. It is not difficult to find that the glare effect after rain is very serious in the field of view outside the tunnel. At 16:00 p.m., the \(PGSV\) glare value in the access zone of Longquanshan No. 1 tunnel was 7.1017, far exceeding the unbearable glare limit. Compared with the glare value in normal weather, the glare value in the condition after rainfall is larger. Therefore, it was found that the glare phenomenon is more serious in the condition after rain than in the condition under normal sunshine. If this situation occurs in the morning (afternoon) on the road surface of the tunnel facing due east (due west), the uncomfortable glare will be more serious, affecting the safety and comfort of driving in the access zone of the tunnel. Reference [29] suggests that a reasonable light distribution at the tunnel entrance has an impact on the driver's perception of brightness and glare issues. During the day, the sunlight shines directly in the direction of the driver's entry into the tunnel. Moreover, there is a significant difference in illumination between sunlight and tunnel lighting, which can cause problems and seriously interfere with the driver's vision [30]. Disability glare is caused by improper luminance distribution, excessive luminance variation, or excessive contrast, resulting in a decrease in the ability to see important objects clearly. [PERSON] pointed out that disabling glare reduces the contrast of obstacles on the road, lowers safety levels, and leads to a significant increase in traffic accidents. Therefore, the author believes that in the access zone of the tunnel, the luminance difference inside and outside the tunnel should be minimized to reduce the human eye's dark adaptation time [4], so that the driver has good visual adaptability when entering the tunnel. Similarly, for the generation of glare at the scene, the following specific measures can be taken. First, in response to the landscape factors outside the tunnel, dark vegetation can be planted outside the tunnel [31], and anti-glare buildings can be constructed [32; 33] (such as persoda and tunnel sunshades) to reduce the luminance of the surroundings outside the tunnel, thereby reducing the difference in luminance between the inside and outside of the tunnel. These methods will  
Figure 18: \(PGSV\) for the west portal of the Longquanshan No. 1 Tunnel. reduce glare values. Second, in response to the road surface factors outside the tunnel, asphalt pavement or dark colored pavement should be laid on the road surface to reduce the contribution value of the road surface brightness near the tunnel entrance, slow down the luminance difference inside and outside the tunnel, and thus reduce the impact of uncomfortable glare on driving safety [34].