Study on the Glare Phenomenon and Time-Varying Characteristics of Luminance in the Access Zone of the East–West Oriented Tunnel

Abstract

In response to the special feature of the east–west oriented road tunnel entrance being easily exposed to direct sunlight, a study was conducted on the glare phenomenon at the access zone for this type of tunnel and on the time-varying characteristics of the L20(S) value outside the tunnel. First, the actual situation of luminance difference inside and outside the tunnel was considered. Field tests were carried out in a 20° field of view of the human eye within a stopping distance. Then, the environment paraments outside the tunnel were collected by combining the environment schematic method with the digital camera method. Finally, the differences and time-varying characteristics between the measured and recommended values of luminance outside the tunnel were analyzed. The PGSV daylight calculation model was used to analyze the glare effect in the 20° field of view of the human eye. The results indicate that the luminance L20(S) outside the tunnel towards the east (west) generally shows a trend of first increasing and then decreasing, and reaches its maximum value in the morning (afternoon). The difference in the contribution ratio of luminance inside and outside the tunnel for this type shows an overall trend of first increasing and then decreasing, and the maximum difference appears in the morning (afternoon), reaching about 97% and 96% respectively. The time-varying characteristics of glare in the access zone of an east (west) oriented road tunnel are roughly consistent with the variation trend of the luminance L20(S) outside the tunnel and exceed the intolerable glare limit. Due to direct sunlight, the luminance outside the tunnel is too high, resulting in an uncomfortable glare that the driver cannot tolerate, becoming more serious after rainfall, and which affects driving comfort and safety.