Design of Solar Optical Fiber Lighting System for Enhanced Lighting in Highway Tunnel Threshold Zone: A Case Study of Huashuyan Tunnel in China

Table 1

Characteristics analysis of solar optical fiber lighting system.

Advantages	Energy saving and environmental protection	(1) Light source of clean energy with little energy consumption and artificial lighting power reduction during the day; (2) No heat effect of electric light source; (3) Good energy efficiency
	Safety and health	(1) Healthy and comfortable lighting environment of high quality by the control of the output of the ultraviolet ray and infrared ray; (2) Fine safety without the power hidden trouble and electromagnetic interference; (3) The fact that it could be used in the special places in cold and wet weather even in flammable and explosive environment
	Easy maintenance	The collected light was the sunlight all by light guiding device, and it could well meet the requirements only to make good maintenance of the light guiding device of the centralized layout.
	Flexible layout	The light output device could achieve a variety of forms of light emitting, such as dot, line, and surface, which would give the lighting design more freedom, diversity, and artistry.
Disadvantage	High cost	The solar tracking device and the quartz optical fiber lighting system with high light transmission efficiency were relatively expensive, so the high cost of the one-time investment and cost performance problem were the major reasons affecting the popularization of light guide lighting system.
	Large attenuation in long distance	Although quartz optical fiber had a high optical transmission efficiency less than 200 m, but its transmission efficiency would drop to 10% for more than 1000 m.