The decision on building railway systems in the past decades was a consequence of irrational decision-making process in many cities, which resulted in numerous complaints in the following years aimed to the systems and their better utilization due to the unfulfilled goals set in the construction. The Republic of Croatia has plans to include railways into urban and suburban public transport in major cities; therefore, it is necessary, as the decision has been made, to examine the railways, and to ensure as probable as possible to make the railway systems become an adequate realistic solution to the problem. The compatibility of the railways as a chosen solution depends on several internal and external factors, where the problem is a result of their number, relations between them, and the fact that their relevance and impact is not the same in each city. The analysis of causality and its effects, in addition to the deduction reasoning, can be conducted by a holistic approach, as representing every included factor and criterion in a hierarchy or network, with every possible outcome. Considering the mentioned, the method of analytic network process (ANP) is an efficient framework for solving this complex problem. Based on the determined factors influencing the level of usage in the planned systems and the relationships between the factors, the ANP model was developed in this paper to assess the importance of each criterion, with testing conducted by group decisions among the members of the expert group. In this manner, the relevance of every considered criterion was determined, with the following ones as dominant: vehicle frequency, ticket pricing and the employment stage. Considering the potential for modelling travel behaviour, i.e. attracting passengers, reliability and service integration become dominant, if the criteria demanding significant financial investments were not considered. The determined criterion relevance enables evaluating projects, and the plan for integrating railways into the urban and suburban traffic in the City of Rijeka is represented in the paper as a case study. In this purpose, the relevance of the objective criteria was determined based on measuring standards, and subjective criteria based on a survey. By gathering the obtained criterion values and their relevance, a 67-percent fulfilment of the successful integration criteria was determined, with the possibility to significantly raise the probability of project success if the offered service was acceptable to the users in terms of pricing, frequency and integration with the existing bus network (about 11 %).