People use descriptions referring to places through their daily life. These descriptions correspond to the region of the real world. We call such descriptions geo-referenced descriptions. We have studied a method of converting such descriptions like addresses and place names into their corresponding geographic coordinates, that is, tuples of longitude and latitude. The process of converting descriptions into coordinates is called geocoding. In this paper, we focus on natural route descriptions as a new type of target to geocode. We first propose Formal Route Statement (FRS) to represent and process natural route descriptions by means of a computer, and then explain a core schema of sidewalk network databases on the basis of a characteristic of natural route descriptions. Also, we present our prototype system to geocode natural route descriptions using sidewalk network databases based on our proposed framework.