Research into the Design of Tunnel Photovoltaic Sunshades Based on Visual Efficacy Experiments

Aiming at the problem of “black hole effect” at tunnel entrances, this study proposes a widely applicable design method for photovoltaic sunshade, which not only verifies the theoretical effect of the design scheme through a combination of simulation and experiment, but also provides sufficient theoretical basis for the design selection of sunshades. This study is divided into the following key stages. First, analyzing the shortcomings of existing studies and clarifying the importance of driver reaction time as a safety indicator. Second, constructing an evaluation framework integrating economy, safety, and visual comfort to ensure the comprehensiveness and scientificity of the evaluation of design options. Then, proposing a series of pre-selected sunshade design options and simulating the illumination changes of each viewpoint in different scenarios by means of the visual efficacy experiments. Subsequently, two-factor ANOVA and simple effect analysis are used to study in depth the mechanism of the influence of the combination of sunshade length and light transmission rate on drivers’ reaction times, and to reveal the role of the key design parameters. Finally, the combined weight and technique for order of preference by similarity to ideal solution (TOPSIS) method is used for comprehensive evaluation and to determine the optimal design scheme. Taking Rongwu Expressway Yingerling Tunnel in China as an example, according to the research and analysis, the recommended design scheme of photovoltaic sunshade is as follows: the total length is 80 m, the combination of light transmittance is 0.8-0.6-0.4-0.2-0.1, and the length of each section is 16 m.