Athens Metro Expansion Raises Safety Concerns After Buildings Are Damaged

The findings were prepared by structural engineer Nikolaos Krasakis and Dimitrios Kaliampakos, a professor at the National Technical University of Athens.

Construction of a new subway line in the Greek capital has caused settlement and structural damage to apartment buildings in Kypseli, a densely populated central Athens neighborhood, according to an independent engineering report that raises questions about the management of one of Greece’s largest infrastructure projects.

The report, commissioned by the City of Athens and local residents, found that ground settlement associated with tunneling for Athens Metro’s new Line 4 reached as much as 55 millimeters in some locations—nearly four times a 15-millimeter safety threshold used for the project. Engineers also calculated building rotations, or tilting caused by uneven settlement, at levels as high as twice the designated alarm threshold.

The findings were prepared by structural engineer Nikolaos Krasakis and Dimitrios Kaliampakos, a professor at the National Technical University of Athens. Their assessment draws on documents supplied by Hellenic Metro, the state-owned company overseeing the project, as well as inspections of affected buildings. The engineers said damage has been identified in both structural and nonstructural elements. Reports for two apartment buildings explicitly record damage to load-bearing columns, while cracks in columns at eight buildings were flagged for further investigation.

Of 14 apartment buildings for which documentation was provided, only three remained classified as low risk after the tunnel-boring machine passed beneath the area. Initial post-construction assessments classified three as medium risk and five as high risk. Documentation was missing for three others. Subsequent assessments placed six buildings in the medium-risk category and one in the high-risk category.

The dispute also centers on the availability of information. The independent engineers said Hellenic Metro and project contractors had not provided several documents they requested, including complete technical assessments, construction logs and detailed data on pressure at the face of the tunnel-boring machine. Documents eventually delivered to Athens authorities covered 14 buildings, although residents of at least 25 buildings have reported damage.

The report argues that the available measurements demonstrate that the project’s original assumptions underestimated its impact on surrounding buildings.It recommends comprehensive structural-safety and repair studies for affected properties and says necessary remediation should be completed before tunneling resumes in the area.