Diagnosis of the track superstructure is a significant element among the factors contributing to improvement of technical condition of railway infrastructure in Poland. Monitoring of the changes taking place on the running surface of the rails is very relevant taking into account the level of rail transport safety. The paper presents some factors influencing the process of degradation of the rail running surface as compared to selected defects considered and defined in the Catalogue of Rail Defects of the Polish Railway Lines. Some of the technical-operational parameters used in the analysis of the reasons for wear of railway rails are: the type of transport, traffic intensity and maximum allowable axle load. Based on the track geometry data, the places endangered by particular types of damage are specified. The results of the analysis may be used in further studies on the degradation of railway infrastructure in Poland.