Abstract: The invention is concerned with in situ moulding of concrete pipelines and comprises apparatus having a moulding unit which is movably supported on preplaced support units by a cantilever beam. The moulding unit includes an inner mould former which corresponds to the internal cross sectional shape of the pipe to be formed and having an upper inner portion and a lower inner portion, and an outer mould former which extends over the top and upper side portions of the upper inner mould former in spaced relationship to define a mould cavity within which the top and upper side portions of the wall of the pipe is formed. The underside of the outer mould former is open so as to expose the mould cavity to the base of the trench within which the pipeline is being formed. A method for using the apparatus includes the steps of locating the trackway in a trench, moving the moulding unit along the trackway, and simultaneously pouring a concrete slurry into said mould cavity.