The energy waste due to excessive lighting in a tunnel is addressed by designing a fuzzy packet identifier(PID) control algorithm for tunnel lighting based on optimizing the brightness reduction coefficient. First, using Matlab software, the brightness reduction coefficient proposed in Guidelines for Design of Lighting of Highway Tunnels 

 is optimized using the linear fitting method, obtaining the value based on realtime vehicle speed under large and small vehicle flow conditions. Second, the linear interpolation method calculates the optimal  value based on the realtime traffic flow, obtaining ondemand lighting brightness values under realtime traffic flow and vehicle speed in each tunnel section. Third, the ondemand lighting brightness deviation value and change rate are considered as input variables. An adaptive fuzzy PID controller is designed to control lamp light input variables, revealing an energy conservation control mode of tunnel lighting on demand. Finally, the simulation and field tests are conducted. The results show that under the condition of ondemand tunnel lighting, the internal tunnel lighting based on optimized brightness reduction coefficient  can reduce power consumption by approximately 21.2% compared with the traditional control mode setting, positively affecting energy conservation and emission reduction of the tunnel lighting system.