METHOD OF ESTIMATION OF TRAFFIC INFORMATION, DEVICE OF ESTIMATION OF TRAFFIC INFORMATION AND CAR NAVIGATION DEVICE

There is provided a method and a device for accurately estimating traffic information of a link having no traffic information even if different types of roads are mixed. The device finds a parameter characterizing a damping curve of a quantity of change of relative speed based on stored traffic information for links on a city center side on a minimum-time cost route connecting the city center and suburbs, finds a quantity of change of relative speed of the link having no observed traffic information and estimates its traffic information based on the damping curve. The device also calculates a ratio of quantities of change of relative speed of two links whose road types change as a speed change similarity ratio and estimates traffic information of the link of a second road type from known traffic information of the link of a first road type by using that ratio.