How can the signal tower come down when the light bulb is changed?

The signal tower climbed down after changing the light bulb. According to the relevant public information, the staff climbed to the top of the tower at an altitude of 600 meters, and then climbed down after the change. Generally, the top of the signal tower has the function of issuing early warning signals, and some of them are densely arranged with 5-meter-high LED light sources, which can display different weather conditions through remote information input according to the six colors specified in the weather forecast and early warning standards.