Method for outputting a direction instruction by a navigation device which comprises map data representing a majority of intersections, the method comprising the following steps: Preparing an optimised set of rules for assigning road segments to turn directions by selecting several intersections of the majority of intersections, assigning to each of the selected intersections a target direction indication related to a combination of an entry segment and an exit segment of the intersection, whereby the target direction indications are assigned to the selected intersections by a human observer or by several human observers, and performing an optimisation procedure which comprises an evolutionary algorithm considering several initial rules sets, the target direction indications and those map data which represent the selected intersections, whereby the initial rules sets are configured in such a way that with them a direction instruction for an intersection is generable considering an entry segment and an exit segment of the intersection, and those map data which represent the intersection, whereby the method comprises the following steps in addition: determining a route, selecting an intersection which is passed by the route from the majority ty of intersections, determining an entry segment and an exit segment of the intersection by means of the route, generating a direction indication for the intersection by using the optimised rules set, whereby the entry segment, the exit segment, and those of the map data which represent the intersection are considered, generating a direction instruction for the intersection based on the direction indication, and outputting the direction instruction to a user of the navigation device. Preparing an optimised set of rules for assigning road segments to turn directions by selecting several intersections of the majority of intersections, assigning to each of the selected intersections a target direction indication related to a combination of an entry segment and an exit segment of the intersection, whereby the target direction indications are assigned to the selected intersections by a human observer or by several human observers, and performing an optimisation procedure which comprises an evolutionary algorithm considering several initial rules sets, the target direction indications and those map data which represent the selected intersections, whereby the initial rules sets are configured in such a way that with them a direction instruction for an intersection is generable considering an entry segment and an exit segment of the intersection, and those map data which represent the intersection, whereby the method comprises the following steps in addition: determining a route, selecting an intersection which is passed by the route from the majority ty of intersections, determining an entry segment and an exit segment of the intersection by means of the route, generating a direction indication for the intersection by using the optimised rules set, whereby the entry segment, the exit segment, and those of the map data which represent the intersection are considered, generating a direction instruction for the intersection based on the direction indication, and outputting the direction instruction to a user of the navigation device. determining a route, selecting an intersection which is passed by the route from the majority ty of intersections, determining an entry segment and an exit segment of the intersection by means of the route, generating a direction indication for the intersection by using the optimised rules set, whereby the entry segment, the exit segment, and those of the map data which represent the intersection are considered, generating a direction instruction for the intersection based on the direction indication, and outputting the direction instruction to a user of the navigation device.