A New Paradigm for using GNSS for Road Tolling

Bern Grush and Preet Khalsa

Abstract:	Transportation demand management, transportation funding, and the greenhouse gas (GHG) contribution from vehicles are combining to force many transport authorities worldwide to consider wide area tolling programs that charge based on time of use, distance traveled and place of travel (Time-Distance-Place, or TDP pricing). Programs that use GPS for reliable tolling have succeeded in open sky, but not in built up cities. Over a six-year period starting in 2002, we have developed a solution to the urban canyon problem that is specific to road tolling, parking and pay-as-you-drive insurance. This involves proprietary filtering of ranging signals and a body of optimized and tolling-specialized GIS algorithms that guarantee “same-trip, same-charge”. Following a short review of early GNSS tolling methods adopted from automotive navigation, microwave tolling and mobile asset management, we consider several critical differences between the application of GNSS to navigation and its application to tolling, including: error tolerance, the efficacy of map-matching, the admissibility of human-in-the-loop and the criticality of real-time (zero lag). We will argue that these differences call for a new look at the use of navigation techniques in tolling applications. We argue for a novel, liability-critical approach to the solution for GNSS-based road tolling rather than simply waiting for improvements in real-time navigation capability in harsh environments. Our approach, by turns, mitigates positioning error, distance errors and finally charging errors in order to produce reliable, accurate and repeatable charging measurements. We outline a new architecture, some high-level processing steps, and illustrate some recent results. We describe a case study involving multiple-vehicles, multiple-routes, over many tens of repetitions in a very challenging urban canyon in Seoul Korea. We assert this same system architecture is able to handle related applications such as parking, insurance, congestion mapping, etc., allowing a broader package of transportation demand tools for our congested surface networks. We conclude that GPS, deployed this way, is now ready to provide road-use metering in any signal environment and that “financial-grade” data from such a system will be of sufficient evidentiary quality to be used in court to prove that time, distance and location were correctly metered.
Published in:	Proceedings of the 2009 International Technical Meeting of The Institute of Navigation January 26 - 28, 2009 Disney's Paradise Pier Hotel Anaheim, CA
Pages:	617 - 622
Cite this article:	Grush, Bern, Khalsa, Preet, "A New Paradigm for using GNSS for Road Tolling," Proceedings of the 2009 International Technical Meeting of The Institute of Navigation, Anaheim, CA, January 2009, pp. 617-622.
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