Nowadays, when discussing the improvements in the quality of life, all the necessary information and all the needed resources are available to people. A recurring problem that is often talked about in theory, but which is seldom seriously dealt with in practice, is the implementation of sustainable development in economic activities such as tourism and transport. Conceivably, as of now, the best solution seems to be - the railway. Rail traffic is fast, efficient, environmentally non-invasive as well as comfortable and safe, while allowing for transport of a large number of passengers within a small volume of space. Connecting railway lines within the territory of the Republic of Croatia, but also beyond its borders, is necessary for the creation of modern railway infrastructure which would favor sustainable development. The railway is particularly important for the area of Krapina-Zagorje County, which is an example of one of the most successful tourist destinations in mainland Croatia, with its untapped overall potential. Therefore, it is necessary to invest in the development of the County by encouraging sustainable tourism and transportation, which would improve the tourist facilities, ensure the most efficient transportation grid and increase the income from economic activities, in addition to the overall GDP. Balancing transport supply and demand with tourism is economically achievable, socially acceptable, technologically feasible and necessary for the future, in order for sustainable development to be implemented in Croatia.