The Department of the Environment, Transport and the Regions (DETR) has embarked on a programme of research into road user charging. The first phase of the programme took place at the research track facility of the Transport Research Laboratory (TRL) between November 1996 and June 1997. Technology trials were undertaken with two electronic fee collection (EFC) systems supplied by Bosch Telecom Gmbh and GEC-Marconi Communications. The trials investigated the 'front end' of tolling systems, namely the tolling transaction, violator detection and vehicle classification components. This paper describes the trials design and the preparation of an infrastructure at the test track suitable for trials of both motorway and urban road charging systems. A dedicated trials support system was configured and comprised a trials computer system, a video monitoring system, a vehicle location system and an environmental monitoring station. Trials scripts were developed for a range of trials scenarios and used as the basis for testing the EFC systems with a range of vehicle manoeuvres, including manoeuvres not possible on a live motorway. The trial programme provided the opportunity to investigate the technologies and the potential of EFC systems for application on the UK motorway network. In parallel with the test track trials programme, a separate and wide-ranging programme researched specific tolling-related issues which were reported to the DETR to provide additional information on the tolling technologies and to support policy development. The next phase of the UK charging programme is also discussed following the Government's White Paper on the future of transport.