In this paper, we propose a framework for solving the novel problem of role discovery in a public transportation network (PTN). We model a PTN as a weighted node-attributed network whose nodes are public transport stations (stops) grouped with respect to their geospatial position, node attributes store information about social infrastructure around the stations (stops), and weighted links integrate information about the travelling distance and the number of hops in the transportation routs between the stations (stops). Our framework discovers meaningful node roles in terms of both topological and infrastructural features of a PTN and is capable of extracting useful insights about the overall PTN’s efficiency. We apply the framework to the newly collected open data of St Petersburg, Russia, and point out some transportation and infrastructural weaknesses that should be taken into consideration by the city administration to improve the PTN in the future.