Redistribution of internal forces in existing bridge structures occurs very often in practice, especially when they are functionally modernized (e.g. by widening the deck), as well as as a result of changes in the static system of the structure. As a result of changes, internal forces are redistributed, and insufficiently accurate consideration of this can lead to serious, negative consequences. The article analyzes a real bridge structure located in Opole. The bridge structure was modeled in the numerical program SOFiSTiK. Work on the model was divided into several stages. The first one was a comparison of internal forces for the state before 2015, obtained from loads according to the standard from the time of construction of the structure and Eurocode. The second stage was a change in the static scheme (widening the usable width of the roadway) and a comparison of internal forces and as above. The third part included the elimination of hinges. Based on the conducted analyses, three cases were compared and conclusions were drawn, which show that even a small interference in the bridge structural system can have a significant impact on changing the system of forces.