Analyse et reconstruction d'un alignement routier a partir de traces GPS.

摘要

The knowledge of the characteristics of road alignments is very important for roads network managers. These characteristics have been obtained by surveying for a long time, but these methods are long, tedious and expensive. In fact, the network in the province of Quebec counts more than 20000 km of two-lane rural roads.; Now, the development of the GPS is such that it is possible to expect the rise of faster and cheaper methods to obtain the characterisitics of roads alignments. The goal of this paper is then to follow up the research led by Vouland (2005) and corrected by Jacquart (2005) and Durlut (2006) in order to provide an algorithm able to recreate the characteristics of horizontal and vertical alignments from GPS coordinates surveyed in the field.; First, a theoretical approach is developed. Each point is allocated to a straight line or a curve and the characteristics of these elements are calculated. Multiples circles and parabolas represent a difficulty because the tangents between the curves are not known. A method is therefore proposed in order to obtain their characteristics as well. Hence, as all the elements of the alignments are known, new coordinates can be computed. A VBA program is then developed to put into practice the theory and data created from known elements are tested. The advantage of these theoretical alignments is that the results the algorithm must provide are already available. Thereby, the algorihtm can be calibrated and validated.; Then, a practical approach is developed, based on the theoretical approach. Some changes are however added. The GPS data are collected via a vehicule equiped with a GPS receiver which surveyed coordinates about every 20 meters along the central axis of roads. These data include therefore some errors linked to the GPS technology. For this reason a sensibility value is added, outliers are detected, circular and parabolic paths are estimated via least squares regressions and the data consistency is checked. A program is also developped and tested with GPS data provided by the Ministere des Transports du Quebec, that enables the validation of the algorithm.; The features of road alignments are useful to establish a database with all the network roads, This database will be used to pursue studies on level of service, signalisation installation or passing problems for instance.