Design of Counter Beam Tunnel Lights for CIE 88？:？2004 Regulation in Threshold Zone

To enhance driving safety, a counter beam light is proposed to meet CIE (International Commission on Illumination) specifications for tunnel lighting. The proposed new counter beam light (CBL) acts as a qualified counter beam light to help tunnel road lighting meet the CIE 88？:？2004 regulation standard in the threshold zone in both simulation and in practice. Through appropriate arrangements of the counter beam light and conventional fluorescent lights on the tunnel ceiling, we demonstrate that road tunnel lighting meeting CIE 88？:？2004 standards can be accomplished. Based on LiteStar four-dimensional simulation, the source file created through the measurement of the proposed CBL prototype achieved an average road surface brightness of 121？cd/m2, which is greater than the minimum regulation level of 105？cd/m2, a brightness uniformity of 0.88 (minimum regulation level of 0.4), longitudinal brightness uniformity of 0.98 (minimum regulation level of 0.6), a glare factor of 4.41% (maximum level of 15%), and a contrast revealing coefficient of 1.08, which is above the 0.6 minimum level in the threshold zone