GPS-GIS-based procedure for tracking vehicle path on horizontal alignments

This article presents a global positioning system-geographic information system (GPS-GIS)-based procedure for the deduction of the horizontal alignment of a road based on the path of a control vehicle. Using differential GPS surveying, field data were collected at a 0.1-second interval, under different speed conditions on a 25-km section of a two-lane rural highway in eastern Ontario. The raw GPS data were post-processed to filter out the possible errors and then imported into a GIS environment for analysis and interpretation of the results. An extension for ArcView was written to determine the geometric features of the highway horizontal alignment, including the tangents, spirals, and circular curves. Values were obtained for the radius and length of nine circular curves, length of spirals, and the lateral position of the vehicle path along the straight and curved segments. These values were compared with the same features of the actual highway alignment. The results showed that the developed procedure and ArcView extension could produce the horizontal alignment of a road quickly, accurately, and for a relatively low cost. In addition to the extraction of the horizontal alignment of a road, the procedure can be used to track the actual vehicle path under normal driving conditions and compare it with the horizontal alignment of a road in an investigation concerning driver behavior.