Congestion charging is generally regarded as an effective tool to manage the ongoing growth in road use and to abate congestion. However, public support is typically very low and therefore very few charging schemes have been implemented. The concept of tradable peak credits (TPC), which is based on the cap-and-trade principle, has characteristics that are believed to lead to more public support. First, a TPC system is revenue-neutral since the money circulates within the user group. Also, the expected effectiveness, and thereby support, may be higher because, in a TPC system, the operator has more control over the inflow of cars due to the firm cap. Lastly, the allocation of free credits provides the opportunity to address equity issues. This paper aims to quantify the levels of support for TPC among the public and to explore what the influence of scheme design, personal characteristics and attitudes is on these levels of support. To that end, a stated choice experiment has been conducted in which respondents were asked whether they would vote for the implementation of different TPC schemes. The discrete choice model shows that 32%, and up to a small majority of 52%, would support different TPC schemes. Most people, however, like or dislike TPC regardless of the scheme design. It is attitudes, and to a limited extent also socio-demographics, that relate to someone's level of support, rather than the scheme characteristics. Support is especially higher among people who find TPC fair and effective, who live outside the borders of the municipality and are lower educated. Although the results indicate that a small majority would support a TPC scheme, directions for future research are given to supplement this study.

Tradable credits for congestion management are a novel policy concept that is receiving increased interest in transportation research. This interest is mainly driven by the belief that the concept can count on stronger social support and hence has a better prospect for implementation than charging-based instruments. This paper is the first to provide an analysis of the social, political, economic and technical feasibility of this concept. To this end, policymakers and researchers from the field of transport have been interviewed. The results reveal so many barriers and challenges in the social and political context that some seem insurmountable, which exposes a difference with expectations formulated in the literature. We reflect on possible options to overcome or avoid barriers but conclude that the concept of tradable peak credits lies very far from the current way of thinking about road use and seems unable to compete with more established charging schemes.

A deep understanding of people's support for road pricing may help policymakers to design more practical pricing schemes that are effective in abating congestion but lead to less public opposition. This study adds to the rich body of road pricing acceptability literature by taking a different approach that focuses on the underlying pattern of the arguments, beliefs and attitudes, which largely determine the viewpoint of individuals with respect to road pricing. We apply Q-methodology to find these viewpoints by asking respondents to rank order subjective arguments that are subtracted from the public debate on road pricing and to identify shared viewpoints that are called frames. Analysis revealed four frames: The polluter should pay, Focus on fair alternatives, What's in it for me? and Don't interfere. Only the Polluter should pay frame is positive about road pricing. The other three frames are negative about road pricing, which suggests that there is not just one single block of citizens opposed to road pricing, but that quite different arguments are used in the various frames. We discuss how these frames can be used by policy-makers that intend to implement road pricing, to fine-tune the design, communication and implementation process of road pricing schemes.

Congestion is threatening the accessibility and liveability of urban regions. Cities are usually hesitant to consider the effective, yet controversial idea of congestion pricing as a measure to abate the growing economic and environmental problems. In the longstanding search for an effective and acceptable pricing scheme, there has been an increased interest in tradable credits. Compared to charging instruments, this novel concept has the theoretical advantage that it can better address equity issues while effectively reducing congestion. Although one may argue that tradable peak credits (TPC) lead to higher public acceptability, very few empirical studies have researched this. Therefore, this study explores attitudes towards TPC using five focus groups with Dutch citizens. The participants were confronted with a hypothetical city where two instruments were suggested: peak charge (PC) and TPC. Most participants preferred PC and only two participants supported TPC while opposing PC. The advantages as addressed in literature played minor roles in the discussions. Participants revealed a sceptical attitude towards TPC or were more convinced about PC. Contrary to expectations, the attitudes became more negative as the discussions developed. Based on these insights, we propose directions for future research to assist the search for an acceptable congestion pricing instrument.