Patent ID: 8145414

Claim:
A traffic information estimating method of a traffic information estimating device having at least a CPU (Central Processing Unit) for executing arithmetic processing of data; a road network information storage section for storing connection data of links composing a road network and types of roads; a link traffic information storage section for storing observed traffic information of part of links composing the road network and for storing estimated traffic information of the links other than the part of the links: the CPU executes steps of: calculating a quantity of change of relative speed that is a quantity of change of link speed from a reference speed as data indicating a degree of congestion of the link based on traffic information stored in the link traffic information storage section; calculating a damping parameter that characterizes a damping curve along which the calculated quantity of change of relative speed damps in accordance with a distance from a city center along a route from the city center to a suburb or from the suburb to the city center of the road network; calculating a ratio of quantities of change of relative speed of two forward and following links whose road types change along the route of the road network bound for the suburb from the city center or from the suburb to the city center as a speed change similarity ratio; estimating traffic information of a target link for which the observed traffic information is not stored in the link traffic information storage section by using the traffic information stored in the link traffic information storage section for the link on the city center side on the route of the road network bound from the city center to the suburb or from the suburb to the city center, the damping parameter calculated for the target link in the damping parameter calculating step and the speed change similarity ratio calculated for the target link in the speed change similarity ratio calculating step, and storing the estimated traffic information into the link traffic information storage section as the traffic information of the target link.