TERRATEC EPB TBM Nears Halfway Point on Bucharest Metro Line 6 South Section
TERRATEC reports continued progress on the South Section (1 Mai–Tokyo) of Bucharest’s Metro Line 6 (Magistrala 6), where its refurbished Ø6.39m Earth Pressure Balance (EPB) TBM has advanced beyond the future Gara Băneasa metro station and is now around the halfway mark of the 6.6-km twin-tunnel drive. The South Section is being delivered for network operator Metrorex by the Alsim Alarko–Makyol Joint Venture, which was awarded the contract in March 2022.
The South Section forms part of the wider Metro Line 6, which will run 14.2 km via twin tunnels and 12 new stations, connecting Gara de Nord in central Bucharest with Henri Coandă International Airport. Along the South Section, the alignment serves six stations — 1 Mai, Pajura, Expoziției, Băneasa, Washington and Tokyo. Since launching in April 2025, the machine has navigated a demanding sequence of ground conditions — sand, clay, silt and gravel layers with a shallow water table and unpredictable overburden as thin as 10 m in places. One of the drive’s most technically sensitive stretches took the TBM beneath Herăstrău Lake, where the alignment passed within 2.5 m of an adjacent tunnel and close to the foundations of a bridge dating to the 1930s. Tight control of face pressure allowed the machine to cross safely without disturbing either structure.
TERRATEC’s on-site field engineers have supported the machine throughout, including a mid-drive cutterhead inspection and tool change near the Tokyo station launch point, where the team switched from disc cutters to rippers to suit the changing ground. The refurbishment program carried out ahead of the project — drawing on the machine’s prior operating history — has proven central to its reliable performance across this constrained urban alignment.
Looking ahead, the JV is preparing for higher groundwater flow in the sections still to come, and has worked with the TBM manufacturer to introduce additional pressurised air at the cutterhead to manage water ingress. The final stretch of the drive will bring the machine within 3.5 m of the existing M4 tunnels as it connects beneath the existing 1 Mai station, an approach requiring significant ground improvement work.
Civil works on the South Section remain on track for completion in 2027, with the full M6 route to Bucharest’s international airport targeted to open in 2028 — delivering Romania’s first direct rail link between the city center and Henri Coandă International Airport.
As a leading manufacturer of Tunnel Boring Machines, Raise Boring Machines and Microtunnelling Systems, TERRATEC continues to support complex urban tunnelling projects across Asia, Europe and the Americas with tailored machines and dedicated field support.
