Track-laying works of Tianjin Metro Line 4 southern section conclude, China June 23, 2021 | Asia Pacific News The track-laying works of the southern section of Line 4 of Tianjin Metro have been completed. This section spans 19 km and covers 14 stations. Trial operations are expected to begin by end-2021.... This content is available to only subscribers. Username or E-mail Password Remember Me Forgot Password