The paper describes the project of European initiative EUREKA “Ecological mountain railway as an element of the sustainable development of a tourist region in Poland” joining the spas of Piwniczna with Szczawnica. After presentation of the project scope and the partners, the municipalities which serves and links planned narrow-gauge railway have been characterized. Reflection of an idea for the railway in the existing strategic and planning documents has been identified. Functions of the railway and its situational and altitude alignment of its route are specified. The vehicles of the railway and the rules and examples for creating of schedules are generally characterized. The rules for construction of prognostic passenger flows by rail are described and selected results are quoted. The conclusions from the analysis of the environmental impact of the railway and the result of financial and economic analysis are presented. List of the expected main effects of the project and its potential impact on the development of transport technology is given. An idea of enlargement the territorial scope of the narrow-gauge railway project with proposal for its internationalization is presented. This includes extension of the route from the Szczawnica spa to the Krościenko spa and the branch route from the Obidza pass to the Stara Lubovna town in Slovakia. For this purpose an initiative will be taken to apply a research project of the European Union.