A computer-implemented route planning method comprises determining source and destination nodes in a graph data structure based on a route planning query, executing an initial graph search on the graph data structure using graph costs based on real-time traffic data, wherein the initial graph search starts at the source node and settles nodes until it stops, and computing one or more routes to the destination node from one or more of said settled nodes using precomputed data based on traffic prediction data, thereby to determine a route from the source node to the destination node via one of said settled nodes.