Tunnelling completed on Riyadh Metro Line 5; track laying begins on Line 4 June 9, 2016 | Middle East & Africa News Tunnelling work has been completed on Riyadh Metro Line 5 (Green Line). Herrenknecht supplied two, 19-metre wide tunnel boring machines (TBMs) for Line 5 and three additional TBMs for the remaining pr... This content is available to only subscribers. Username or E-mail Password Remember Me Forgot Password