Development of Satellite Based Positioning and Navigation Facilities for Precise ITS Applications

Recent advance in network reference based real-time kinematic GPS (NRTK GPS) positioning makes it possible to track moving objects up to centimeter accuracy. This capacity will undoubtedly help implement many new applications for future ITS services, for instance, precise navigation, autonomous driving, lane based traffic or fleet management, lane based road use charging, and law enforcement. To support these activities, a testbed network of GPS reference stations has been established jointly by the authors institute and Leica Geosystems (UK) in the past three years. This testbed NRTK facility covers an area of about 20,000 km² in the central region of the United Kingdom. Real-time raw GPS measurements are streamed to a data server situated in the University of Nottingham via broadband connections. Real-time corrections that are used to compensate spatially correlated errors and biases between the reference station network and user terminals are generated by the data server and sent to those authorized user terminal receivers wirelessly for delivering real-time position solutions of centimeter accuracy. Trials have been carried out recently on a variety of different classes of UK roads to test the delay and completeness of the NRTK corrections, wireless connection and coverage, positioning accuracy, etc, aiming at the evaluation of the feasibility of NRTK GPS positioning for rapid roadway geometry data acquisition and the exploitation of this latest technology for ITS related applications and services. This paper presents the recent work and findings of the authors and the preliminary conclusions are drawn from field trials.