Rockfalls, as a type of geological hazard, are especially important along the roads and railways. In terms of proactive management approach, it is necessary to standardize a method which allows comparison between slopes and logical separation of those that represent a priority for remediation. For its implementation, selection of the relevant parameters and the manl'ler of their rating is required. In this doctoral dissertation they are based on several versions of existing Rockfall Hazard Rating System. However, the main aim of the research is focused on system modification to the slopes along railways in carbonate rocks of Croatia. The system is based on an exponential scoring of engineering geological (EG) and climatic characteristics that affect the rockfall potential, and geometric features of slopes that affect the possibility that the material reaches the railway. Data about all these features is collected within a simple observation during EG prospecting. A total of 366 segments of slopes have been analysed. They are spatially located in the Karst Dinarides of Croatia, generally including the area from Rijeka, through the Gorski Kotar area and Lika, to Split. According to the selection parameters and their ratings, 16 scoring models are defined. For each of them, the slope classification is conducted, based on the combination of classes of the total scores of all parameters and classes of the relation between the scores for causes and consequences. The final result represents one of the four defined slope classes according to rockfall threat. The most appropriate scoring model was chosen based on the results of the verification carried out with three sets of parameters. They include information of the preliminary rating, slope stability defined by the Regional Maintenance Administration and traces of rockfall. For the selected model statistical analysis of linear and logistic regression are performed. They enabled the determination of statistically significant parameters for assessing the rockfall threat, as well as the optimization of the scoring model. The main elements for the development of rockfall threat system are elaborated. Those represent the first step in the comprehensive rockfall hazard and risk management.