The CRH Maintenance Bureau generally checks the status of the high speed trains every night after 10 p.m. It takes four hours to check a train. The CRH (China Railway High-speed) Maintenance Bureau, located in Jinan, Shandong province was officially put into operation on July 1, 2011. The bureau, known as the"4S shop" for high speed trains in China, is in charge of the reparation and maintenance of high-speed trains.