What are the working hours of Qingdao subway signal maintenance?

9 am-9 am the next day. The signal maintenance shifts of Qingdao Metro are closed by turns, with the morning shift at 9: 00- 19:00 and the evening shift at 19:00- 9:00 the next day. When there is no maintenance task at night, you can rest in the duty room and rest for two days in the last four days. Qingdao, also known as Island City, Qingdao and Jiaoao, is a prefecture-level city, a sub-provincial city, a city with separate plans and a megacity under the jurisdiction of Shandong Province, China. Located in the south of Shandong Peninsula.