The described technology is generally directed towards policy based navigation control. Map inputs including, e.g., information about blocked routes or other map information, can be collected from mobile devices. Policies can be applied to the map inputs in order to generate navigation advisories that synthesize information from multiple map inputs. For example, a size and shape of a route blockage zone can be determined from multiple discrete map inputs. In some embodiments, the techniques disclosed herein can be applied in connection with shared overlay maps to support automated, real-time, cross-platform sharing of map information, including navigation advisories, among digital navigational map users, including but not limited to unmanned ground vehicles.