The article is aiming to analyse the concept of urban-rural interface. This concept is distinctively interpreted by various sciences such as physics, chemistry, biology, informatics and geography. The study is meaning to come up with an approach where polycentric development and the regional transport system play a part in adjusting and strengthening the complex ties between the urban space and the rural space. The case study focuses on the City of Bucharest metropolitan area. The study presents the area's specific features, emphasizing those elements that favor the optimal functioning of the mutual ties between metropolis and the adjoining space. Dysfunctions can be corrected by implementing a regional transport system, with a role in enhancing the cities' polarization role, and also in optimizing inter-settlement ties.