Bilbao Metro Line 4 has moved forward. The province of Bizkaia in northern Spain and the Basque Government approved the agreement. It covers financing and construction of the planned route. This is reported by the railway transport news portal Railway Supply.

Bilbao metro Line 4 budget estimated at EUR 412m
Bilbao metro Line 4 budget estimated at EUR 412m

According to the Basque Government, the initial estimated construction budget is EUR 412 million. Also, this amount could be adjusted as the technical designs now in preparation progress. Under the agreed financing structure, Bizkaia will provide 45% of the total cost. This corresponds to about EUR 200 million through 2032. At the same time, the Basque Government will finance the remaining 55%.

A December 2025 project study by the Basque Government lists these estimates for the works:
• Construction cost budget: EUR 318.2 million;
• Tender base budget: EUR 458.2 million;
• Administration reference budget, excluding VAT: EUR 412 million.

The new 6.7 km Bilbao metro line is expected to be completed within six years.

Bilbao metro Line 4 and territorial cohesion

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

With the agreement approved, Bizkaia reaffirms its backing for strategic mobility infrastructure in the territory. Line 4 will strengthen rail transport as a key element of public mobility. Also, it will support social and territorial cohesion in Bizkaia.

The project responds to the mobility needs of residents in Enkarterri and southern Bilbao. In addition, it will reinforce public transport’s role as a driver of territorial cohesion. It will improve connectivity between regions and their links with the capital.

Rekalde, Zorrotza and Enkarterri connection

The agreement includes the development of the Rekalde–Zorrotza section. It also covers the connection of the Enkarterri rail network in the Irauregi–Alonsotegi area.

Still, this element requires further development. It depends on several complex administrative procedures involving different institutional responsibilities. The two administrations have committed to facilitating and accelerating the required institutional steps. Those steps are needed to carry out this transfer.

Both institutions regard the new metro line as a priority project for mobility. Within that scope, the route is treated as an extension of Line 3. It is also treated as a connection between Bilbao and Enkarterri. It will link Matiko with Alonsotegi in Enkarterri. Its stations will include Deusto, near the University, Doña Casilda Park, Plaza Elíptica, Zabalburu, Irala, Rekalde, Basurto and Zorrotza.

ETS design and construction role

For delivery, the administrations have assigned the role to Euskal Trenbide Sarea (ETS). ETS is the Basque Government’s railway infrastructure body. It will be responsible for design and construction from Matiko to Rekalde. This includes the approach to Basurto.

In addition, Line 4 will use railway infrastructure between Enkarterri and Bilbao. Enkarterri is a metropolitan area in western and south-western Bizkaia. That infrastructure is currently owned by Spain’s railway infrastructure manager Adif. Both administrations have undertaken to complete the procedures needed for the management of that infrastructure.

The planned line is designed as an extension of Line 3. It will serve Rekalde, Irala and other districts in southern Bilbao. It will also serve Enkarterri. There, the project is intended to improve suburban rail network connections around the city.

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