Sofia Metro 3 Line Project

The Metro 3 Line Project eases traffic on some of the most congested boulevards while linking the city's southwestern neighborhoods with its eastern districts. The entire line is 16 kilometers long and includes eight aboveground and 11 underground stations. Line 3 interchanges with lines 1 and 2. It passes below sensitive buildings like the Law Office Rusinova and Rasheva and crosses under the Perlovska River. The main tunnel consists of a single tube configuration excavated using an Earth Pressure Balance (EPB) Tunnel Boring Machine (TBM) with a boring diameter of 9.4 meters. 
 
TYLin was responsible for the detailed design of geometrical and structural segmental lining, as well as TBM definition and follow-up until commissioning, ground treatments, monitoring, TBM entrance and exit, EPB pressure, and temporary works. During construction, TYLin monitored the TBM performance and designed a solution for building an intermediate connection shaft to minimize the work inside the main tunnel, avoid interference with the TBM operations, and allow most construction operations to advance regardless of the TBM position.