This article describes two approaches to Electronic Toll and Traffic Management (ETTM) interoperability, and comments on prospects for Vehicle-Roadside Communication (VRC) standards. Current ETTM equipment has little or no interoperability, because of major differences in the design and operation of available tag and reader products. Existing products usually involve backscatter reflection or active transceivers as basic modes of communication between roadside equipment (readers/antennas) and in-vehicle equipment (tags or transponders). The two basic approaches to providing some interoperability between incompatible VRC systems are: (1) reader level interoperability, which focuses on reading equipment able to communicate with tags of different communications modes, protocols, data formats, and codings; and (2) tag level interoperability, which allows devices to recognise and communicate with many types of readers. Both types of interoperability could give toll operators and agencies the ability to extend ETTM services to more customers. The two possible approaches to reader level interoperability are: (1) the parallel reader approach; and (2) the multi-mode reader approach. Although the agreed formal standardisation of VRC may be distant, a de facto VRC standard might develop relatively quickly.
Abstract