continuous extensions of operating time, the problems of aging equipment and increasing passenger demand will further increase the operating pressure of the two lines. In June 2021 it was announced that Shanghai Metro has started to update of the signal system of lines 3 and 4 and finish before December 31, 2024. These are the last lines in the system that are equipped with fixed block Alstom URBALISTM 200 system, not equipped with CBTC systems capable of headways as low as 90 seconds. CASCO successfully won the bid for the renewal and transformation of the signaling for lines 3 and 4 using its self-developed Qiji TACS system. Rolling Stock References Shanghai Metro lines Railway lines opened in 2000 2000 establishments in China 1500 V DC railway electrification