By rosebell
Herrenknecht EPBM Vitosha has reached the future Sitnyakovo station on Sofia Metro Line 3 Slatina extension, with approximately 900m of tunnelling remaining before completion of the mechanised drive.
According to Sofia Metro operator Metropolitan EAD, Vitosha has excavated approximately 3.75km, completing around 80% of its planned drive. The TBM will now continue from Sitnyakovo to a retrieval shaft at the G.S. Rakovski Military Academy, with tunnelling expected to be completed by the end of 2026.
The TBM works are being delivered by the DVU 21 joint venture, comprising Doğuş İnşaat ve Ticaret, Via Construct Group and Ultrastroy.
Vitosha Advances on Sofia Metro Line 3
The approximately 6km Slatina extension forms a branch of Sofia Metro Line 3, connecting the Oborishte and Slatina districts with Tsarigradsko Shose Boulevard near St Anna University Hospital.
Vitosha has a cutterhead diameter of approximately 9.4m and is advancing at an average rate of 10m to 15m per day. The machine is excavating a single twin-track tunnel with an external diameter of 9.05m.
The tunnel is being lined with precast concrete segments, with more than 22,000 segments required for the complete drive.
TBM Passes Five Future Stations
Construction of the Slatina extension began in late 2023, when Vitosha was launched from a shaft at Tsarigradsko Shose Boulevard in Sofia’s Mladost district.
Since launching, the TBM has passed through the future Trakia, Arena Sofia, SK CSKA, Slatina and Geo Milev stations before reaching Sitnyakovo. Station structures are constructed in advance, allowing the TBM to pass through the stations as excavation progresses.
Final 900m Through Dense Urban Area
One of the main challenges identified by Metropolitan EAD is tunnelling through Sofia’s densely developed urban environment, where the alignment intersects areas containing extensive water, sewerage and electrical infrastructure.
The final approximately 900m will take Vitosha from Sitnyakovo to the retrieval shaft at the G.S. Rakovski Military Academy. Following completion of excavation, the TBM will be dismantled and removed.
Vitosha was originally manufactured by Herrenknecht for an earlier section of Sofia Metro Line 3. The EPBM was previously used on the central Line 3 section before being refurbished and deployed on the Slatina extension.
