Tunnel lighting systems serving pedestrian and vehicular traffic must simultaneously satisfy visual performance requirements and energy efficiency constraints. This study investigates the optimization of tunnel lighting design using a sustainable engineering approach based on Response Surface Methodology (RSM) and Specific Lighting Energy Consumption (SLEC). Software-assisted lighting simulations were performed for two tunnel geometries—straight and double-curved—and horizontal (Eh) and vertical (Ev) illuminance levels were evaluated at five representative locations. The resulting data were used to construct RSM-based predictive models and to assess energy performance through SLEC. The effects of mounting height, luminaire spacing, luminous flux, number of luminaires, and tunnel type were systematically analyzed. The results demonstrate that luminaire spacing is the dominant parameter influencing illuminance levels and energy consumption. An optimal configuration consisting of a 12 m luminaire spacing, 5 m mounting height, and 10,000–12,000 lm luminous flux achieved a favorable balance between lighting quality and energy efficiency. Additionally, straight tunnels exhibited higher illuminance uniformity at shorter spacings, whereas curved tunnels showed improved performance under wider spacing conditions. The proposed RSM–SLEC framework provides a robust, data-driven methodology for sustainable tunnel lighting design without compromising safety or visual comfort.
İmal et al. (Tue,) studied this question.