Visibility Enhancement and Power Saving by Pro-beam LED Tunnel Lighting Method

Abstract

The symmetrical lighting system, which is appropriate to recognize an object with silhouette vision, has been used for many years as tunnel interior lighting. The pro-beam lighting system however has an advantage to enhance visibility with reversed silhouette and has being investigated for more safe and comfortable driving in the tunnel for several years by the NEXCO group, especially to increase visibility for a preceding vehicle to prevent rear-end collisions. The pro-beam lighting with ceramic metal halide lamps was largely adapted for 70 tunnels of New Tokyo–Nagoya expressway in 2012, and further study has being made to achieve both good visibility and power efficiency with the use of LED pro-beam lighting. In this paper, the research concerning to pro-beam lighting are described such as visibility analysis of LED tunnel lighting, enhanced visibility by pro-beam, and evaluation of experimental installation by both field observations and the mathematical values of total revealing power. The evaluation of the LED pro-beam tunnel showed good visibility and power efficiency.