Design and Prototyping of Efficient LED Counter Beam Light with Free-Formed Surface for Meeting International Tunnel Lighting Standards

Abstract

An LED Counter Beam Light (CBL) with a free surface secondary lens is proposed to enhance the safety and efficiency of tunnels. The secondary lens was designed and produced to be mounted on a 50 W white-light LED array to generate the targeted counter beam pattern, in order to meet the standards for enhanced tunnel road lighting of the CIE (Commission Internationale de l’Eclairage)—CIE 88:2004—in a trial tunnel lighting scheme. Through the simulation of a road tunnel in Northern Taiwan using the LiteStar four-dimensional software, it was shown that the proposed LED light can serve as a qualifying CBL to generate an average road tunnel surface luminance (Lav) of 182.76 cd/m2, which is better than the 138 cd/m2 that commercial High-Pressure Sodium (HPS) tunnel lights can provide and the 181 cd/m2 minimum stipulated in the CIE 88:2004 regulations. The results also show that the proposed LED light accomplishes a contrast revealing coefficient qc of 1.03, which is above the minimum regulatory level of 0.6 for a qualified CBL, as well as a luminance uniformity Uo of 0.89 (regulatory minimum, 0.4), longitudinal luminance uniformity UL of 0.99 (regulatory minimum, 0.6), and glare factor TI (threshold increment) of 7.24% (regulatory minimum, 15%). In order to test the feasibility of the LED CBL for future commercialization, the proposed LED CBL was prototyped and measured; the results demonstrate that an average road surface luminance (Lav) of 184.5 cd/m2, intensity of the luminance uniformity Uo of 0.7, intensity of the longitudinal luminance uniformity UL of 0.94, glare factor of 7.04%, and contrast revealing coefficient qc of 1.38 can be achieved, which are all above the levels required by the CIE 88:2004 regulations.

Modeling Night and Daylighting Toll Road Tunnel Using Dialux to Compare the Performance of HPS and LED Lamp

“…The significance of the research lies in its potential to contribute to energy efficiency, safety, and sustainability in tunnel lighting for transportation infrastructure. This finding suggests potential improvements in energy efficiency within tunnel environments, contributing to sustainable lighting solutions for transportation infrastructure [27], [10].…”

“…Thus, the lighting must also be more resistant to dangerous substances in vehicle exhaust gases such as sulfuric acid, nitric acid, carbon monoxide, etc. Several types of lamps recommended for tunnel lighting are High-Pressure Sodium (HPS) lamps and Light Emitting Diode (LED) lamps [24], [27], [28], [29].…”

An asymmetric road lighting concept: Probeam

“…Furthermore, to realize Probeam lighting, it is necessary to design lenses in front of the (small sized) LED sources to generate the appropriate light distribution. 23,40,41 Although the Probeam concept seems to have some important advantages with respect to visibility and contrast, there are also some practical limitations. In Probeam luminaires, the light intensity is distributed over a narrow solid angle, as can be observed in Figure 6 (left).…”

The research for designing the LED tunnel light for highway tunnels

“…The Hsuehshan Tunnel model was built with DIALux software to simulate mixed lighting with two lenses, and the changes in average brightness, total uniformity, and longitudinal uniformity were calculated. Liao et al [ 17 ] proposed a counter beam light per the CIE 88–2004 standard to assist road lighting in tunnels and improve driving safety. Applying the LiteStar 4D simulation environment, the proper arrangement of the counter beam light and the conventional fluorescent light on the tunnel ceiling can be obtained, and also correspond with the CIE (International Commission on Illumination) specification.…”