In the coming days, the tunnel boring machine (TBM) “Athena” is expected to break through at the shaft located at the intersection of Vasilissis Konstantinou and Michalakopoulou streets, marking a critical milestone for Greece’s largest ongoing public infrastructure project. This moment, known in the engineering world as a breakthrough, signifies the tunneling machine breaking through the final wall of the shaft, an important step in the construction process.
Meanwhile, the second TBM, “Niki”, is advancing from the opposite direction. It began at Alsos Veikou and is tunneling a 7.5-kilometer route toward the same Evangelismos shaft. Having passed Galatsi and the Elikonos station, it has now reached just past Kypseli Square, completing 2,960 meters of tunneling—about 42% of its route. From there, it will continue beneath the Courthouses, Alexandras Avenue, Exarchia, Akadimias, and Kolonaki. Overall, roughly 65% of the Line 4 tunnel has been excavated.
Once Athena reaches the Evangelismos shaft, the 100-meter-long TBM will be disassembled, lifted to the surface, and stored according to manufacturer specifications for future use. This will be followed by the construction of the stations, the next major step in the realization of the new metro line.
The first phase of Line 4 will connect Alsos Veikou with Goudi, covering 12.8 kilometers with 15 new stations and a total budget of €1.8 billion. It will be Athens’ first metro line featuring fully automated trains and platform screen doors. The estimated daily ridership for the initial Alsos Veikou–Goudi section is 340,000 passengers.
The total project duration has been set at 2,920 calendar days (8 years) from the signing of the main works contract. Having started on June 22, 2021, construction is expected to be completed by June 20, 2029.