Restructuring or converting network data is an essential function of the geographic information system (gis) when adapted to transportation. Implementing effective data restructuring models in the gisallows users to collect and maintain data in the format with which they are most familiar while allowing others to use it in a format they require. Milepoint referenced data in road inventory files provide valuable network information for transportation research. Individual records in these files represent variable-length sections of roads. A new record is created each time a highway attribute changes. Consequently, a segment of road between two intersections may be represented by one or more records in a road inventory file. Further, all attributes in these records are associated with both directions oftravel along a section of road. Many transportation analysis modelsrequire networks to be represented by a node-link data structure inwhich nodes symbolize an intersection of two or more roads. Additionally, if a road is two directional, it is represented by two links, each of which has its own set of attributes. To utilize road inventory data in these analysis models, network information has to be converted from milepoint to an intersection/link format. This process involves aggregating and disaggregating attribute data to represent longer and shorter road segments, and also disaggregating data into bidirectional information. Data conversion efforts are needed to produce intersection/link network representations from milepoint data. Amicrocomputer model for data conversion is developed and application issues and model sensitivities are addressed. This paper appears in transportation research record no. 1261, Geographic information systems 1990.
Samenvatting