Patent ID: 8918279

Claim:
A route search device, comprising: a communication module configured to communicate with roadside radio beacons and a traffic center, the roadside radio beacons providing basic congestion information and the traffic center providing center traffic information, the basic traffic information being congestion information for specific links that correspond to roads on which the roadside radio beacons are installed, and the center traffic information being congestion information for links that correspond to roads on which the roadside radio beacons are not installed; a memory storing a route search program; and a CPU that, by executing the stored route search program: acquires the basic congestion information from the communication module, receives an input setting a destination; searches for a first travel route from a departure point to the set destination using the acquired basic congestion information; determines, based on the first travel route, whether the center traffic information is necessary to be acquired by: (i) determining whether congestion information for any of the links included in the first travel route was not included in the basic congestion information; (ii) when congestion information for each link included in the first travel route was included in the basic congestion information, determining that the center traffic information is not necessary; (iii) when congestion information for any of the links included in the first travel route was not included in the basic congestion information, assuming that the congestion state of each link for which congestion information was not included in the basic congestion information is congested, and searching for a second travel route from the departure point to the set destination; (iv) determining whether the first route matches the second route; (v) when the first route matches the second route, determining that the center traffic information is not necessary; and (vi) when the first route does not match the second route, determining that the center traffic information is necessary; when it is determined that the center traffic information is not necessary, communicates the first travel route to a user; and only when it is determined that the center traffic information is necessary to be acquired: acquires the center traffic information from the communication module; and searches for a third travel route from the departure point to the set destination using the acquired center traffic information; and communicates the third travel route to a user.