Automated Identification and Extraction of Horizontal Curve Information from Geographic Information System Roadway Maps

Transportation Research Record: Journal of the Transportation Research Board, No. 2291, Transportation Research Board of the National Academies, Washington, D.C., 2012, pp. 80–92. DOI: 10.3141/2291-10 Z. Li, Room 1249A Engineering Hall; M. V. Chitturi and A. R. Bill, Room B243 Engineering Hall; and D. A. Noyce, Room 1204 Engineering Hall, Traffic Operations and Safety Laboratory, Department of Civil and Environment Engineering, 1415 Engineering Drive, University of Wisconsin–Madison, Madison, WI 53706. Corresponding author: Z. Li, [email protected]. Moreover, other researchers have revealed that crash rates increase as the degree of curvature increases and that a curvature of 15° or greater has a high probability of being hazardous (4, 5). Nationwide, a research framework has been formed by research projects that have been conducted to better understand the relationship between the characteristics of horizontal curves and crashes and to explore effective countermeasures to prevent crashes from occurring on horizontal curves (6–8). Identifying where horizontal curves are located and what the geometric characteristics of the curves are is an essential and important task in solving the curve safety issue. In the United States, many states have a horizontal curve database for their state routes and Interstate highways; however, most of them do not have such a database for county and local roads, and it is costly and time-consuming to collect this curve information through the traditional approaches. In this context, a high priority should be given to the development of an approach that can identify location and geometric information for state and county or local highways in an accurate, cost-effective, and time-efficient manner. To date, satellite imagery, Global Positioning System (GPS) survey data, laser-scanning data, and AutoCAD digital maps are four sources that are widely used by researchers to obtain horizontal curve data. Successful applications based on these four sources are well documented in the literature (9–18). Geographic information system (GIS) roadway maps are becoming more accessible and widely used by most government agencies and research institutions and provide an alternative source for horizontal curve data extraction. Compared with the traditional data sources, GIS roadway maps have the following potential advantages: