1. A computer-readable medium comprising a map database, the map database comprising: representations of road segments, wherein at least some of the road segments are represented by two separate types of data, wherein the two separate types of data include a first type of data that indicates a location of a line that coincides generally with a physical centerline of the represented road segment, wherein the data that indicates the location of the line includes a location of at least two nodes, and a second type of data that indicates a shape of the represented road segment, wherein the data that indicates the shape represents a substantially continuous curve that is independent of node location.