Basement floods in central Athens raise concerns over Metro Line 4 construction

Basements in a large public-sector building on Vasilissis Sofias Avenue flooded about a month ago, leading to an evacuation and a night-long inspection by National Technical University of Athens experts. The incident coincides with the arrival of the tunnel-boring machine for Metro Line 4 near Evangelismos station, prompting officials to consider a connection between the works and changes in the local groundwater table.

Similar concerns have followed a sidewalk collapse earlier this year and multiple cracks and basement floods. Specialists, including emeritus professor Panagiotis Karydis, explain that excavation depth, soil type and the timing of concrete lining installation can affect underground water flow and cause subsidence. Engineers from the Technical Chamber of Greece, the metro consortium, and resident groups are conducting round-the-clock inspections and drafting repair proposals, while heavy rain has worsened damage in several apartments. Residents have asked Elliniko Metro for pending geotechnical reports ahead of a court hearing scheduled for December 9 and have met with Parliament Speaker Nikitas Kaklamanis to demand faster remediation.