In the past few years a growing number of cities have started monitoring the position of public transportation vehicles using GPS devices. Most of these trajectory data are released in raw format and usually have issues, such as measurement errors. Providing insights from these valuable (and noisy) data is a major challenge in larger cities. In this paper we present a system, called Vistradas, for visual analytics of urban trajectory data. Vistradas allows users to analyze use cases related to trajectories of public buses such as: analysis of bus uniformity, verification of bus route, and the impact of events in bus traffic. Our proposed Vistradas system helps user to get insights into various aspects of public transportation.