Road Traffic Data (RTD) Visualization is an important subject in the development of an Intelligent Transport System (ITS). With the abundance of data formats available today, standardization often goes in favor of commercial products. In parallel, there is considerable and painful work of open source development, which resulted in the provision of high quality products capable of handling a variety of formats at the same time while providing comparable capabilities for spatial data analysis and presentation. Here an open source-based solution for RTD visualization is presented, that offers full scalability in data collection, processing and visualization. A case study of road traffic data solution has been chosen for concept and architecture validation, providing an excellent development framework. Road traffic data has been presented in a form of geospatial database layer, built atop of previously established layers of city transport network. Further research will be focused on development of advanced functionalities for geospatial data analysis and means of data presentation that suit most the requirements set by the ITS end-users.