London has a long history of successful schemes for bus priority at traffic signals. Recently, Transport for London (TfL) has procured a modern automatic vehicle location (AVL) system for bus fleet management, passenger information and bus priority. The new system is known as iBUS and is based on global positioning system (GPS) and supporting technologies for bus location. The system eliminates the need for on-street hardware for detecting buses and provides more flexibility and opportunity for using bus detectors. However, bus location based on this system is less accurate than location based on fixed infrastructure (e.g. beacons) and could result in reduced benefits from bus priority. This paper first summarises how bus priority at traffic signals works within iBUS, and then explores the effects of GPS locational errors on bus priority benefits. This is followed by a discussion of opportunities available in the context of iBUS to build an even more efficient and beneficial bus priority system by taking advantage of its cost-effective multiple detection capabilities. The paper is based on various studies carried out by the Transportation Research Group (TRG) at the University of Southampton for TfL. © 2008 The Institution of Engineering and Technology.