A “vehicle in, light brightens; vehicle out, light darkens” energy-saving control system of highway tunnel lighting

In order to meet the requirements of traffic safety and energy-saving in tunnel, a “vehicle in, light brightens; vehicle out, light darkens” energy-saving control system is proposed. The tunnel lighting control system is designed based on “Guidelines for Design of Lighting of Highway Tunnels (China)” (JTG/T D70/2-01-2014). Firstly, when the approach of a vehicle is detected by the vehicle detectors, the demand luminance of tunnel interior is calculated based on changes of tunnel exterior environmental luminance, traffic volume and vehicle speeds. Then the actual luminance is calculated based on road surveillance images, the incremental PID (Proportional-Integral-Derivative) method was adopted to ensure the actual luminance meet the requirements of tunnel lighting. Further, when there are no vehicles in tunnel, the LEDs will be adjusted to their minimum luminance for energy-saving. The operation results show the tunnel lighting control system contributes to reduce electric energy consumption.