At 5:30 a.m. on December 9, a Shanghai Metro Line 1 train equipped with new signaling system slowly arrived at People’s Square Station, marking the successful switch from old to new signaling system of the first phase of Shanghai Metro Line 1 (Shanghai South Railway Station-Shanghai Railway Station) and the official abandonment of the old signaling system which had been used for as long as 24 years. As the first metro signaling system renovation project that maintained the original signaling system in China, it’s the third signaling renovation line successfully delivered by CASCO after Beijing Metro Lines 1 and 2.  

Senior management of Shentong Metro and CASCO gathering on site to witness the switch from old to new signaling system of Metro Line 1

Officially put into service in 1993, the signaling system of Shanghai Metro Line 1 has been in service for 24 years, making it the oldest metro signaling system in Shanghai. With the expiration of equipment life cycle and increasing demand for operation reliability and stability, it was imperative to upgrade the signaling system. 

The renovation of existing lines is much more difficult than the construction of new lines. In order not to disturb the normal operation, there was only 3 hours at most for renovation construction every day. Apart from limited working time, the working site was also greatly restricted as the old system and the new system, which was tested at night, had to share many outdoor facilities. All of it posed extremely high demand for the stability and reliability of system technology, the professional level and project management experience and capacity of the execution team. CASCO, as the only signaling enterprise with signaling system renovation project experience in China, was appointed to provide new signaling system for Shanghai Metro Line 1 and take charge of the switch from old to new system. 

Initiated at the end of 2013, the project was the first rail transit signaling system renovation project that maintained existing system mode. As the original system was quite aged with lack of relevant materials, it was essential to reinvestigate and confirm onsite data, and young technical personnel of the project team needed to study these “ancient” technologies. It took nearly two years for preliminary design and preparation of the project, and another two years for onsite project implementation. The testing engineers could only work for two to three hours late in the night when the line was out of service to complete installation and testing task for the day, and restore the existing system early in the morning of the next day to ensure the normal operation of the line. In order to make full use of the limited time, the project team racked their brains and carried out repeated researches and analyses to continuously improve implementation plans, process steps and switch process. They even innovatively adopted homemade relay as the switch to reduce new and old system switch time and earn more effective testing time. 

Hundreds of switch cables in the seemingly simple switch relay cabinet

Senior management of the client paid great attention and provided great support to the project. Early in the morning on December 9 2017, system switch of Shanghai Metro Line 1 was successfully completed. The new signaling system which used computer interlocking instead of 6502 relay interlocking, was officially launched and operated, not only improving the reliability and stability of the system, but also reducing train operation interval. And CASCO made significant breakthroughs in the project by implementing signaling system renovation while maintaining existing system mode, which accumulated valuable experience for implementing similar renovations in the future. 

CASCO engineers on site

As of the moment, the old system is still used for Xinzhuang-Shanghai South Railway Station section of Shanghai Metro Line 1, which is to be replaced by the new system in the second half of 2018. After full switch to the new system, departure interval of Shanghai Metro Line 1 will be reduced from 2 minutes and 40 seconds to 2 minutes, which will greatly mitigate operation pressure during morning and evening peak hours and improve operation efficiency.