A method for updating a geographic database is disclosed. Data collecting equipment is installed in each of a plurality of vehicles each of which also has a navigation system. The data collection equipment is used to collect data while the vehicles are being driven along roads by their respective users. In addition, a method for assigning a confidence level to geographic data is disclosed. The confidence level is assigned to the geographic data as an attribute. In addition, a method for determining a position of a vehicle by sensing roadside structures is disclosed. Data indicating positions of roadside structures are contained in a geographic database. By matching positions of sensed roadside structures to data in the geographic database that indicates the positions of the structures, the position of the vehicle while traveling can be determined.