# Reliability Enhancement Driven by ANN for Lighting Control System in Highway Tunnels
###### Abstract  
Compared with open roadways, traffic safety in highway tunnels requires more attention to build smoothly transitioned and well-coupled light environments for drivers to alleviate visual discomfort so as to achieve a balanced sense of driving safety and comfort. In this study, in order to overcome the drawbacks of existing tunnel lighting control modes that disregard the color temperature of natural light characteristics and collaborative influence of color temperature and luminance of natural light on tunnel lighting quality, one artificial neural network (ANN) model is designed and trained to simulate one physical lighting control system that takes into consideration color temperature and luminance simultaneously. In this model, multiple parameters of discrete and continuous types of input layer and output layer are synergistically analyzed. The model was also trained with quantities of field data from one tunnel in service and includes one hidden layer with 10 neurons. The simulation results showed that this model obtains a high degree of fitness with inside luminance and 100% recognition rate with inside color temperature in the threshold zone, which conforms to the regulation strategy of actual lighting control systems with high confidence. The proposed model will greatly enhance the reliability and sustainability of the lighting system during its normal operation, which can also support other lighting scenarios due to its flexibility and scalability with multiple-input and multiple-output (MIMO) capabilities. light environment; tunnel lighting; reliability; ANN; traffic safety +
Footnote †: journal: Applied Sciences  
Studies show that under normal driving conditions, drivers rely on visual cognition to capture more than 80% of road traffic information during driving [3]. The visual condition is closely related to traffic safety, and the light environment conditions of the highway tunnel directly affect drivers' visual characteristics. The tunnel interior space is relatively narrow and well-sealed, and the low brightness level and slow spread of vehicle exhaust fumes limit drivers' visual recognition ability, which heavily impacts on the safety of tunnel driving. When drivers enter the transition area between the natural and artificial light environments, the great difference in light leads to a \"white hole\" or \"black hole\" effect on drivers' vision, thus a \"blind\" vision period is initiated. In turn, the resulting visual discomfort plays a part in some traffic accidents. Human eyes are good at adapting to changing levels of brightness but need some time to adjust, this duration depends on how long light adaption or dark adaption takes for a specific driver. Sudden variations in the amount of light when entering or exiting a tunnel must be avoided as much as possible. In the middle of the tunnel, lighting levels can be lower, but again, avoiding sudden variations is important. Towards the evening, or if the conditions are otherwise darker (for example, in heavy rain), lighting should adapt so that it is dimmer. Psychologically, driving inside a hollow, grey, and unnatural atmosphere may also cause feelings of anxiety. Light uniformity with no yellowish areas or dark corners can bring comfort to an uncomfortable ambient area, and in the case of an emergency, good lighting can also reduce panic and help guide people out. Statistics of accidents in Chinese tunnels carried out by [PERSON] et al. [4] indicate that rear-end collisions caused by failure to maintain a safe distance constituted almost 60% of accidents, and drivers are less effective in perceiving speed and distance when driving in road tunnels. Furthermore, these two factors of psychological and visual impairment are not independent but closely related, creating a negative synergy that possibly increases the risk for drivers in tunnels. This synergy clearly appears in some of the most common disturbing effects (distraction driving, frequent speed change, improper distance maintenance, etc.) in tunnels.