The two projects relate to the planned extension of Lisbon’s yellow and green undergrounds lines and to the construction of new sections of Porto’s metro system, most of which is above ground, including sections between the Casa da Música and São Bento and the expansion of the yellow line, including the construction of a maintenance depot at Vila D'Este, the government said in a statement after the weekly cabinet meeting.

In a later note, the Ministry of Environment, which oversees urban public transport, added that work on both projects is to start in the first half of 2019, for completion in 2023.

In Lisbon, the project is to cost €210.2 million (€83 million of it from the Operational Programme for Sustainability and Efficient Use of Resources or PO SEUR programme agreed with the EU) and involves the construction of a two-kilometre section between existing stations Rato on the yellow line and Cais do Sodré on the green line.

Two new stations are to be built at Estrela and Santos, while Cais do Sodré station is to be remodelled and work done on the viaducts at Campo Grande to link up the green and yellow lines, creating a circular line that the other two lines – red and blue – will intersect.

On 27 November, the Metropolitano de Lisboa, the company that manages the metro, announced that the Portuguese Environment Agency had issued a positive environmental impact statement (DIA) on the project. According to that assessment, the creation of the circular line may jeopardise several national monuments, such as the 18th-century Aqueduto das Águas Livres and Jardim da Estrela; it also notes that the construction of the circular line will make it necessary to shift the railway line between Santos and Cais do Sodré for 44 months.

In Porto, the project is to costs some €307 million (€107 million of which from PO SEUR) and implies building a new, 2.8-kilometre pink line between the Casa da Música and São Bento, with new underground stations Casa da Música, Galiza, Hospital de Santo António and São Bento. The yellow line is also to be extended between Santo Ovídeo and Vila D'Este, with a 3.2-kilometre new section with three new stations: Manuel Leão, Hospital Santos Silva and Vila D'Este.

The €307 million total cost for the Porto project includes €56.1 million in maintenance and the purchase of 18 new carriages.