Sofia Metro Extension Projects
Since 2005, the companies from GEOTECHMIN GROUP have successfully implemented a number of Sofia Metro Extension projects.
Our activities in metro construction started by building Vasil Levski Stadium Metro Station, a Start Shaft for tunnel boring machine (TBM) and an underground connection between Vasil Levski Stadium Metro Station and the existing tunnel under Dragan Tsankov Blvd. The project was implemented by Geotechmin OOD as a subcontractor of the Japanese company Taisei Corporation in the period 2005 – 2009.
Vasil Levski Stadium Metro Station is entirely underground and 16 m deep.
In the vicinity of the metro station, Geotechmin built a start shaft for vertical access of a tunnel boring machine (TBM). The shaft is 20 m deep and its width/length dimensions are 18/20 m. The structure is made of diaphragm walls and reinforced with 4 rows of metal frames
In the period 2010 – 2012, Geotechmin OOD was the general contractor and Geostroy AD was a subcontractor of the project for design and construction of James Bourchier Metro Station and an adjoining tunnel section. The project was funded by the European Regional Development Fund through the Operational Programme “Transport”.
James Bourchier Metro Station belongs to Line 2 of Sofia Metro and is located under Cherni Vrah Blvd. It is 208 m long and 18.7 m wide. The adjoining tunnel section is 215 m long and 15 m wide.
In terms of construction technology, this metro station is one of the most complicated Sofia Metro projects. This is because it was built at a depth of 27 – 22 meters in different sections, and because it was executed in compliance with the Employer’s requirement not to interrupt the traffic along the boulevard throughout the construction process.
A specific characteristic in the execution of James Bourchier Metro Station is the adoption of a pre-stressing technology. It was applied to reinforce the tunnel roof slab and partially the floor slabs in the tunnel and in the station. This method was used for the first time in metro construction in Bulgaria.
In 2013 – 2015, Geometro B.P. Consortium including Geostroy AD as leader and Geotechmin OOD and Metroproekt ООD as partners completed the construction of a metro section towards Mladost 4 Residential District. The section includes Business Park Sofia Metro Station and a 1-km adjoining metro tunnel.
The project was implemented on a design-build basis. The so-called “Milan method” was applied in the construction of the metro station and the tunnel, which are entirely underground. Special supporting structures were built in the sections where the tunnel goes under two existing underpasses and beneath the Banishka riverbed.
The project is funded under the Operational Programme “Transport 2007 – 2013” and co-financed by Sofia Municipality.