Patent ID: 8645065

Claim:
A navigation device which displays traffic lines representing traffic congestion levels along roads in a map image, the navigation device comprising: a traffic information obtaining unit configured to obtain traffic information regarding roads; a road condition determination unit configured to determine whether the roads which have been displayed in a screen include a plurality of roads which belong to a predetermined road type and which are positioned within a predetermined distance of one another or are connected to one another; a traffic congestion determination unit configured to determine, when the road condition determination unit determines that the plurality of roads which are positioned within a predetermined distance of one another or which are connected to one another are included in the roads which have been displayed in the screen, whether at least one road of the plurality of roads has heavy traffic in accordance with the traffic information obtained by the traffic information obtaining unit; and a simple-road-graphic-screen display controller configured to perform control for displaying a simple road graphic screen when the traffic congestion determination unit determines that at least one road of the plurality of roads has heavy traffic, the simple road graphic screen being a graphic screen comprising one window that is configured to display, as simple road graphics, the plurality of roads that the road condition determination unit determines to be positioned within a predetermined distance from one another or connected to one another; wherein the simple-road-graphic-screen display controller is configured to perform control such that a group of a selected road of the plurality of roads and a traffic line corresponding to the selected road are displayed in an emphasized manner in the window of simple road graphic screen relative to other groups of road and their corresponding traffic lines.