Commercial services begin on Suzhou Metro Line 4, China April 19, 2017 | Asia Pacific News Commercial service has commenced on Line 4 of Suzhou Metro. The line spans 41.1 km from Longdaobang to Tongli, covering 37 stations. It was built at an investment of USD5.2 billion. Line 4 comp... This content is available to only subscribers. Username or E-mail Password Remember Me Forgot Password