The province of Bizkaia in northern Spain, and the Government of Basque Country have approved the agreement for the financing and construction of a new metro line in Bilbao.

The initial estimated budget for the construction of Line 4 is EUR 412 million, a figure that may be adjusted depending on the progress of the technical designs currently in preparation. The agreement establishes a joint financing model under which Bizkaia will cover 45% of the costs, representing around EUR 200 million up to 2032, while the Basque Government will fund the remaining 55%.

According to a project study published by the Basque Government in December 2025, the economic estimates for construction are as follows:

• Construction cost budget: EUR 318.2 million;

• Tender base budget: EUR 458.2 million;

• Administration reference budget (excluding VAT): EUR 412 million.

The construction works for the new 6.7 km line are expected to be completed within six years.

The new Bilbao metro line will contribute to territorial cohesion

“Line 4 is an example of the Bizkaia Council’s commitment to developing sustainable mobility that also supports territorial cohesion,” said Leixuri Arrizabalaga, spokesperson for the Provincial Government of Bizkaia.

Through this decision, Bizkaia reaffirms its support for the development of strategic mobility infrastructure in the territory. The implementation of Line 4 will strengthen the role of rail transport as a key element of public mobility and social and territorial cohesion in Bizkaia, responding to the mobility needs of residents in Enkarterri and southern Bilbao. It will also reinforce the role of public transport as a driver of territorial cohesion, improving connectivity between regions and their links with the capital.

The agreement also foresees the development of the section between Rekalde and Zorrotza, as well as the connection of the Enkarterri rail network in the Irauregi–Alonsotegi area. This latter component depends on several complex administrative stages involving different institutional competencies and therefore requires further development. Both administrations have committed to facilitating and accelerating all necessary institutional procedures for the implementation of this transfer.

The new Bilbao metro line is considered a priority project by both institutions, essential for mobility, connecting Matiko and Alonsotegi (Enkarterri), and including stations in Deusto (near the University), Doña Casilda Park, Plaza Elíptica, Zabalburu, Irala, Rekalde, Basurto and Zorrotza.

For its implementation, both institutions have agreed that Euskal Trenbide Sarea (ETS), the Basque Government’s railway infrastructure body, will carry out the design and construction works between Matiko and Rekalde (including the approach to Basurto). Furthermore, since Line 4 will use the railway infrastructure between Enkarterri (a metropolitan area in the western and south-western part of Bizkaia) and Bilbao, currently owned by Spain’s railway infrastructure manager Adif, both administrations have committed to carrying out all necessary procedures for the management of this infrastructure.

The new metro line is designed as an extension of Line 3 and will serve not only the Rekalde and Irala districts, but also other areas in southern Bilbao, as well as Enkarterri, where improved connections with the suburban rail network around the city are needed.