A system for determining a route is provided. The system includes a method for determining estimation function values corresponding to a plurality of vertices on a first graph, where the first graph corresponds to a first route network. The method further includes searching for a first route from a first starting point to the destination on a second graph based on the estimation function values. The system further includes a storage unit and a processor coupled to the storage unit for receiving graph data, where the processor is configured to determine estimation function values corresponding to a plurality of vertices on the first graph corresponding to a first route network, and is further configured to search for a route from a first starting point to the destination on a second graph based on the estimation function values. The device may further include an input unit, a clock unit, a traffic message receiver, and/or a position determining unit.