The operation is characterised by the complete renewal of the track in the section of the Northern Line between Alfarelos and Pampilhosa, construction of two diagonals south of the Apadeiro do Amial, intervention in level crossings, construction of 6 uneven passages, stabilisation of slopes, alteration of the layout of the Alfarelos station and adaptation of the technical building to the service of passengers. Integrates adaptations of the signalling and remote control systems of overhead contact line.