A carriageable duct (1) being part of a sealed pipeline (2), consisting of pipes (3) mutually fixed in correspondence with a coupling condition (A), has at one end a first coupling means (4) and at the remaining end a first locking means (5). In correspondence with a sealing condition (T), the first coupling means (4) is tightly locked with a second locking means (6) and the first locking means (5) is tightly fixed to a second coupling means (7) respectively of an adjacent pipe (3) connected to each free end of the carriageable duct(1). The carriageable duct (1) has a central portion (8) which is reinforced, lowered, indeformable to trampling and it is connected at one end to a first portion (14), to which the first coupling means (4) is connected, and at the remaining end is connected to a second portion (18), with the first locking means (5) connected thereto.
