Abstract: A system and method are provided for forming a map database with attributed data which represents roadways attributed as no-outlet or circular segments. The method includes identifying a segment from a first node to a second node, where the second node is connected to an isolated portion of a road network. The method further includes storing a data attribute into the map database that represents the segment as a road that connects the road network at the first node to the isolated portion of the road network at the second node. The data attribute may represent the segment as a no-outlet segment or a circular segment. A no-outlet segment represents a roadway or portion of a roadway that terminates or returns back to the roadway or portion thereof. A circular segment represents a roadway or portion of a roadway that intersects with a geographic feature, such as a road, and where the roadway or portion thereof leads back to the same geographic feature.

Abstract: System and method are provided for route calculation for use with a navigation system and used with a map database with attributed no-outlet and circular segments. A route calculation program adapted to find at least one solution route, between a first location and a second location on a road network, identifies a segment with a first node and a second node in the road network. From an attribute stored in the map database, the program determines whether the first node is connected to the road network and the second node is connected to an isolated portion of the road network. Using the attribute, the route calculation program determines whether to explore the isolated portion of the road network. In some instances, the program refrains from exploring the segment leading into the isolated portion of the road network and the isolated portion of the road network itself.