This paper presents a study of user responses to the implementation of a high-profile e-government system, the Central London Congestion Charge. The approach is multi-disciplinary, combining human-computer interaction (HCI) and socio-technical systems (STS) approaches to produce an analysis of usability in the payment interactions. Based on interviews with charge payers, we show that usability is an issue in the payment of the charge; the major usability problems are not at the payment interfaces but in the wider interaction. This is compounded by the short time-scale enforced with penalties, and this leads some charge payers to a perception of an adversarial system. SMS is a possible payment route, but currently social and policy reasons work against it. In some social contexts, the simplicity of SMS is appropriate, whereas in others, the familiarity and richer functionality of the Internet and phone are more usable.
