On May 29, Magdalena Álvarez visited the construction site of the new "Cercanías" (commuter rail) station at Puerta del Sol, a project being carried out by FCC Construcción with a budget of 140 million euros.

The new "Cercanías" station—currently under construction—will link Atocha and Chamartín via a single 8,500-meter-long tunnel. This connection will allow the two "Cercanías" lines that currently terminate at Atocha (the C-3 from Aranjuez and the C-4 from Parla) to access the city center directly without requiring transfers, while also improving connections to the Metro network.

The Puerta del Sol station, located in the square of the same name, consists of two main sections: the platform cavern and the entrance hall, which also serves as an interchange with the Metro.

The entrance hall is being built from the surface down, using diaphragm walls and intermediate floor levels. The cavern—unique in the world due to its dimensions (207 meters long, over 20 meters wide, and 15 meters high)—has been designed as a split-level space featuring a lower platform area and an upper level to facilitate passenger flow. Work is currently being finalized on the passageways connecting the station to Metro lines 1, 2, and 3, all of which also pass through Sol.

Safety measures implemented during construction have been a primary focus. From shafts and galleries, ground treatment operations—including consolidation grouting, void filling, compensation, reinforcement, and soil improvement—have been carried out to ensure the complete protection of the buildings and structures situated above the cavern. These measures have protected an area of ​​1.5 hectares, involving a total grouting length of over 15 kilometers.

The impact of these surface and structural treatments is being monitored via 400 control points, with data collected several times a day. This data is analyzed daily to track progress and ensure safety. This instrumentation was complemented by preliminary computer modeling of the cavern's construction process—including reinforcement via grouting—and its potential impact on the surface. The excellent results have demonstrated the suitability of the construction method and the effectiveness of the protective treatments.