Bridge constructions with frame static scheme are proven solution for railway viaducts, which guarantees durability, trouble – free maintenance, appropriate behaviour ensuring the assumption and transmission of vertical and horizontal efforts, redistribution of deformations occurring during the exploitation. The lack of bearings and expansion joints, makes them extremely reliable and adaptable to both the loads and the deformations that occur during the exploitation. An example of such a construction, with a seamless period of operation for more than 30 years, is the bridge in railway area of Station – Poduyane. It is a 3 spans frame structure, with a total length of 105m, with 18 track lines at the Railway Yard Area. In the current article, 2 railway viaducts will be presented – part of the Modernization of the Railway line Sofia – Plovdiv, railway section Elin Pelin – Ihtiman. Specific issues of the design process have been considered, with particular attention to the element stiffness proportion ratio, details of the joints, the effects of temperature, the shrinkage and creeping of the concrete, isolating the abutments from the soil effects / pressure.