Research on Lighting Quality Optimization Method for Highway Tunnels Under Multiple Luminaire Failure Scenarios

During the long-term service of highway tunnel lighting systems, concurrent failures of multiple luminaires lead to severe deterioration of road surface illuminance distribution. Meanwhile, conventional periodic maintenance schemes suffer from significant time latency, failing to ensure driving safety during the maintenance latency period. To address this challenge, this study proposes a highway tunnel lighting quality optimization method based on luminous flux redistribution. First, based on the spatial geometric relationships of failed luminaires, multiple luminaire failure (MLF) scenarios are categorized into four typical topological structures: unilateral continuous failure (UCF), unilateral alternate failure (UAF), bilateral symmetric failure (BSF), and bilateral staggered failure (BStF). The degradation characteristics of average road surface illuminance and illuminance uniformity under each topology are quantitatively investigated. Second, with the optimization objectives of maximizing overall illuminance uniformity (U0) and centerline longitudinal illuminance uniformity (U1), a multi-dimensional optimization model is established. This model incorporates foundational constraints, including driving safety, physical dimming boundaries of luminaires, and road surface illuminance stability. Furthermore, to mitigate the transverse dark bands, lateral illuminance imbalance, and longitudinal fluctuations induced by MLF, four enhanced constraints are introduced: global minimum average illuminance, macroscopic regional symmetry, cross-sectional minimum illuminance, and longitudinal illuminance gradient limits. To efficiently solve this high-dimensional nonlinear optimization problem, a hybrid heuristic particle swarm optimization-differential evolution-simulated annealing (PSO-DE-SA) algorithm integrating PSO, DE, and SA mechanisms is developed. Finally, systematic experimental verifications are conducted across the four MLF topologies in a unidirectional three-lane tunnel scenario. The results demonstrate that for discrete failure scenarios supported by adjacent operational luminaires, the proposed method effectively mobilizes redundant luminous flux to achieve substantial restoration of lighting quality. Specifically, under UAF, the average road surface illuminance is restored to 153.46 lx, approaching the ideal non-failure state; under BStF, U1 increases by 25.02%; under BSF, U1 increases by 23.96%, effectively repairing transverse illuminance faults. However, under UCF involving three or more luminaires, the lighting system reaches its physical dimming compensation limit. Although the overall regional metrics can still satisfy the basic mandatory requirements, the illuminance in the specific lane with failed luminaires cannot be restored to the required standard safety level, leaving localized dark zones. This finding provides a quantitative criterion for determining the triggering threshold of preventive maintenance and luminaire replacement in tunnel operation and maintenance.