Tunnel Entrance Elevation Specifying Device, Method for Specifying Tunnel Entrance Elevation, Computer Program for Specifying Tunnel Entrance Elevation, and Storage Medium that Stores Computer Program

摘要

Systems for automatically specifying a tunnel entrance and methods that accomplish same. One method includes a target entrance selecting step for selecting, from a map data storing portion, a target entrance for specifying an entrance elevation of a tunnel, a target road link assigning step for assigning, from the map data storing portion, a road link, which includes the target entrance, as a target road link, a corrected point extracting step for extracting a certain point as a corrected point, the certain point being located along the target road link and away from the target entrance outwardly of the tunnel by a predetermined distance, a corrected point elevation specifying step for specifying an elevation of the corrected point as a corrected point elevation, and a first target entrance elevation specifying step for specifying the corrected point elevation as a first elevation of the target entrance.