Patent ID: 8108135

Claim:
A traffic congestion degree determination device in a vehicle, the device comprising: a map data input device configured to provide map data which includes speed limit information indicating a speed limit with respect to each of at least one of a plurality of road sections; an external communication unit configured to acquire, from an external traffic information providing center, traffic information which identifies a congested road section from among the road sections and a degree of traffic congestion relative to the congested road section, wherein the traffic information further includes average speed information indicating an average vehicle speed relative to the congested road section; and a control circuit configured to determine whether average speed information indicating an average speed with respect to the congested road section is contained in the traffic information acquired from the external traffic information providing center, the control circuit being further configured to include a first determination unit configured to determine a degree of traffic congestion with respect to the congested road section based on the degree of traffic congestion identified by the traffic information acquired from the external traffic information providing center when the average speed information is determined not to be included in the acquired traffic information, a second determination unit configured to determine the degree of traffic congestion with respect to the congested road section based on the average speed information when the average speed information is determined to be included in the traffic information acquired from the external traffic information providing center and the speed limit information is not acquired within the vehicle from the map data provided by the map data input device, and a third determination unit configured to determine the degree of traffic congestion with respect to the congested road section based on the average speed information and the speed limit information when the average speed information is determined to be included in the traffic information acquired from the external traffic information providing center and the speed limit information is acquired within the vehicle from the map data provided by the map data input device.