Within the designed alignment of E-80 motorway in South East Serbia: Section Dimitrovgrad By-Pass the roadway alignment for the motorway and respective structures has been adopted. In the area of the abovementioned section it is foreseen to build the roadway in twin-tube tunnel Progon with total length of 1100 m.

The terrain is composed of clayey-gravely layers which are present in alternating sequence with sections of clay. The transitions from one into another lithological member are mostly gradual and unclear, seldom sharp, and consequently it is very difficult to single out the boundary between them.

In the course of analysis pertaining to geotechnical construction conditions, the geotechnical zoning of rock masses was carried out, i.e. the constraints were set for terrain parts along the designed tunnel alignment inside which there are similar conditions regarding the tunnel construction. Respecting the previously given criteria, according to geotechnical conditions, in the tunnel tube all singled-out quasi-homogenous zones can be classified into four significantly different categories of rock masses with specific conditions for tunnel excavation and support system.

Taking into account geotechnical conditions found on the location, size and shape of future tunnel, as well as advanced trends in the tunneling, as optimal technical and cost-effective solution, the tunnel construction as per SCL has been adopted. Under specific conditions, SCL thanks to its flexibility, can fulfill the requirements regarding the costs and construction deadlines, validity of the technical solution, and security of manpower and equipment.