obsolete components such as relay interlockings replaced by modern microprocessor-based ones, but the general operation of the signaling system remained unchanged. As of 2020, the original design is expected to serve two additional decades. Rolling Stock In the summer of 2006 after poor cooling effect of the 16 subway DC trains on Line 1 in summer and the high temperature of the carriages had long been a problem, 96 ice cubes have been put into a one-meter-high waste container to alleviate the high temperature of the 16 subway DC trains on Line 1. In order to make up for the defects in the refrigeration power and design of the 16 DC trains, emergency measures must be taken whenever the temperature reaches or more. With the transformation between 2006 and 2008 from 6 carriages to 8 carriages the of the air-conditioning system was improvement, making the ice waste containers something of the past. The line was initially operated by trains built by the German Shanghai Metro Group which included Adtranz (now Bombardier) and Siemens together with AEG Westinghouse and Düwag. Former Rolling Stock References Shanghai Metro lines Railway lines opened in 1993 1993 establishments in China