Trial operations begin on Tianjin Metro lines 4 and 6, China November 5, 2021 | Asia Pacific News Tianjin Metro has begun trial operations on Metro Line 4 southern section and on Metro Line 6 Phase II. The trial runs will end by the end of 2021. The southern section of Metro Line 4 will spa... This content is available to only subscribers. Username or E-mail Password Remember Me Forgot Password