Parameter design of solar optical reflection lighting system array for shadowless lighting in threshold zone of short freeway tunnel

• Published in: Tunnelling and underground space technology Vol. 138; p. 105207
• Main Authors: Shi, Lingna Serena, Tu, Yun, Liu, Zhenyi, Wu, Jinsuo, Yu, Shanchuan
• Format: Journal Article
• Language: English
• Published: Elsevier Ltd 01.08.2023
• Subjects: Energy-saving; Shadowless lighting; Solar optical reflection; Threshold zone; Tunnel lighting; Energy-saving; Solar optical reflection; Shadowless lighting; Tunnel lighting; Threshold zone
• ISSN: 0886-7798; 1878-4364
• DOI: 10.1016/j.tust.2023.105207

•A shadowless lighting approach improves performance of solar optical reflection lighting system.•A fast and simple parameter design method is developed for shadowless lighting.•Effectiveness of shadowless lighting approach is verified by the application in real tunnel. A solar optical reflection (SOR) lighting system has been developed to illuminate the threshold zone of short freeway tunnel in the premise of zero energy consumption. To improve the limited illumination performance of SOR lighting system due to the obstruction of moving vehicles on reflected sunlight rays, this study develops a fast and simple parameter design method for shadowless lighting based on an array of multiple SOR lighting systems that makes reflected sunlight emit to the threshold zone from different angles. The effectiveness of shadowless lighting is verified by the application on a two-lane freeway of Shaanxi Province, China. Results show that the shadowless lighting can significantly improve the illuminance in threshold zone, and the improvement rate is higher for the area farther from the tunnel entrance inside the tunnel. In order to achieve shadowless lighting avoid both the vehicle and inter-system blocking on reflected sunlight, the systems should be installed roadside in a staggered array that: 1) their heights descend and lateral distances from the curb shrink in turn from near to far from the tunnel entrance, with as small vertical and horizontal deflection angles of the reflectors as possible, or 2) their heights remain identical with a reduction in the vertical deflection angles of the reflectors from near to far from the tunnel entrance.