To prevent incorrect road surface information from being distributed to a vehicle.
With respect to each of low friction road surface sections, a distribution determination device 23 calculates ratio of a shadowed area on the road surface between the time when the low friction road surface section is determined and the time when the information distribution is requested. On the basis of the calculated rate, whether environment of the road surface is changed or not is determined from the time when the low friction road surface section is determined to the time when the information distribution request is received. A collection/distribution system 25 is controlled so that the information on the low friction road surface section, where the environment does not change from the time when the low friction road surface section is determined to the time when the information distribution request is received, is transmitted to the vehicle. The incorrect road surface information is prevented from being distributed to the vehicle 1 because the information on the low friction road surface section, where the environment of the road surface changes from the time when the low friction road surface section is determined to the time when the information distribution request is received, is not transmitted to a vehicle 1.
Iwa Saki Kokuni
Kawamata Sumio
Masakazu Ito
Shunichi Takahashi
Toshio Takamatsu