The generation of travel time data is disclosed in which coordinates are received for a starting location (1901). A maximum travel time is received (1903) and processed graph data is read that includes nodes representing pre-filtered map features and edges representing travel times between nodes. A temporary graph is built (1907) of selected nodes that can be reached via selected edges within the maximum travel time. Candidate destinations are received (1908) and the travel time to these candidate destinations is tested (1909) with reference to the temporary graph.