Efforts to advance national interoperability for tolling systems are gaining momentum, with one protocol promoted by a key operator group emerging as a candidate to form the basis for full AVI interoperability, Tim McGuckin writes. Fuelled by a growing awareness and acceptance of standards-based solutions, the US toll community is quickening towards the goal of interoperability between toll systems across the US. Over 20 years since the advent of electronic toll collection (ETC), key elements are falling in