Thessaloniki Submerged Tunnel

— Project Description:

In the Outline Design of the project, two technical solutions were considered:

• Solution A, which included the construction of a twin tube road tunnel, with left bore length of 1,980m and right bore length of 2,337m.
• Solution B, which included the construction of a twin tube road tunnel, with left bore length of 2,568m and right bore length of 2,527m.

In both solutions A and B, TBM entrance and exit shafts were considered, as well as ramps to reach the entrance and exit shafts, with the use of Cut & Cover structures and open U-shaped technical works. Also, in order to provide access to the right branch tunnel from the Stratou Avenue, a 300m long conventionally driven tunnel was considered. The TBM twin road tunnel has an external excavation diameter (TBM diameter) varying between 13.7m and 14.5m, depending on the highway section, the ventilation type, the cross-passages, the TBM tail span and other elements, which were considered.
In the Preliminary Design of the project the following technical works were designed:

• 1,779.9m-long, single-tube, double-deck tunnel, with an external excavation diameter of 15.9m;
• Cut & Cover access structures (including the TBM entrance shaft) in the west landward part of the project, with a total length of 950m;
• Cut & Cover access structures (including the TBM exit shaft) in the east landward part of the project, with a total length of 800m;
• Access ramps, consisting of open U-shaped technical works, with a total length of 1,000m;
• Special cross-passages between the upper and the lower deck of the tunnel were provided in order to facilitate the evacuation of each one of the tunnel decks in the case of fire.

— Description of Services: