The Common Structureof Gee-Based Data for Roadway Information Systems

M any transportation agencies are currently involved in computerizing large quantities of gee-based data that have been traditionally relegated to filing systems. The advantages of such computerization include quicker access, more easily understood presentations that result in better interpretations, improved updating capabilities, and a more centralized and controllable source of information. The overwhelming disadvantage of such computerization is the cost encountered during the initial acquisition and coding of relevant gee-based data. The bulk of these costs arise from the task of attaching x and y coordinates to traditional data. The sheer magnitude of these costs is the probable reason that many transportation agencies have waited so long to begin computerization. Given the costs involved in computerization, it is imperative that comprehensive, efficient, and versatile data structures be used, else the agency will periodically need to incur considerable expense to overcome deficiencies in the data structure design. The objective of this article is to present an overall framework for designing comprehensive data structures that are suitable for roadway information systems. This framework is based on the findings of an ongoing research project at the Pennsylvania State University. Results from this project will be used to illustrate important points concerning the overall structure of roadway gee-based data systems. The article begins with a general overview of roadway data base needs. Next, the importance of identifying such specific roadway facilities as signs, intersections, bridges, and so on is stressed. This section is followed by a discussion of important structural definitions and the process by which roadway facility attributes are stored. Concerns relating to data input and retrieval are then outlined and illustrated. The article concludes with a summary of findings and a discussion of the importance of properly specified data structures for roadway information systems. Overview of Roadway Data Base Structural Needs