Tunneling work has begun for the Madrid Metro Line 11 extension, a project backed by an investment of EUR 880 million.
A ceremony marking the launch of the tunnel boring machine (TBM) took place on 26 March at the future Comillas station. According to Isabel Díaz Ayuso, the President of Comunidad de Madrid, the project represents “the most significant infrastructure work in many years” and is expected to transform both the Madrid Metro system and the daily travel habits of millions of passengers.
The administrative procedures for the northern extension of Line 11 will strengthen the public transport network by linking Mar de Cristal with Valdebebas. The route will serve key destinations such as IFEMA Madrid, the future Ciudad de la Justicia de Madrid, and Terminal T4 of Adolfo Suárez Madrid-Barajas Airport.
The extension will span approximately 8 km, of which 6 km will be excavated by the TBM. The line will start at Mar de Cristal (Line 8) and continue via Ciudad de la Justicia, Hospital Enfermera Isabel Zendal, Airport T4 (interchange with Line 8), and Valdebebas Norte. Completion of the works is scheduled for 2031.
The TBM is a state-of-the-art tunnelling machine that will excavate the 5,593-metre section between Comillas and the new Conde de Casal interchange, at an average rate of 15 metres per day, or around 500 metres per month. This section will include five new stations: Comillas and Madrid Río, as well as interchange stations at Palos de la Frontera, Atocha and Conde de Casal.
More than 300 workers are involved in the project, operating in continuous shifts seven days a week to maximise progress. The TBM will only stop for maintenance and replacement of worn components, while simultaneously installing tunnel lining rings made up of seven prefabricated segments.
Construction of this section will require 32,000 tonnes of steel and 210,000 cubic metres of concrete, as well as the installation of more than 25,000 tunnel segments, which have been produced since September 2025 in a dedicated facility.
The regional government will allocate over EUR 739 million to this phase, which represents the first step of a broader expansion of Line 11. The full project will extend to 33 km, linking Cuatro Vientos with Valdebebas. Of the total investment, EUR 586 million will be dedicated to the construction of the tunnel and the five stations.
The project also includes measures to minimise environmental impact, such as the restoration of parks and green areas, as well as compensatory works in nearby urban green spaces.
Madrid Metro Line 11 extension is designed to significantly improve connectivity between the southern and eastern parts of the city.
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