The public typically considers urban congestion to be a serious problem. In the scientific community it is considered basic knowledge that pricing is often the only effective way to mitigate such congestion. However, implementation of congestion charging continues to meet hard resistance from the public, and politicians continue to rule out that policy option referring to lack of public acceptance. Many authors have explained the paradox by the public?s (layman) suspicion that charging would not be effective and not reduce congestion. From a number of implemented schemes, we also know that once they have experience from (the effects of) charging, the public tend to change to more positive, which seems to support the hypothesis that lack of experience and erroneous subjective predictions of effects causes ?the problem?.
To analyse the hypothesized causal link this study explores how the (i)attitudes towards congestion charging in Stockholm and (ii)the expectancy/understanding of the effects of charging (co-)varied over time and between individuals in the Stockholm public during different phases of the implementation process: before (autumn 2005) and during the Trial (spring 2006), and after permanent introduction of charging (autumn 2007).
For the analyses, we have employed ordinal logit models. This allows us to draw conclusions on the simultaneous relation(s) between acceptance on one hand and individual background characteristics, personal experience and understanding of effects on the other. One of the many advantages with the analytical approach employed is that it allows us to control for, for example, car ownership in the analyses of gender differences in attitudes and predicted effects ? which has given new insights compared to the one-dimensional analyses presented earlier.
A brief summary of results: The differences between men and women in attitudes and understanding of congestion charging are negligible when difference in car availability is taken into account. The frequently discussed difference between inner city inhabitants and people living in the regional periphery, too, turns out to be largely explained by differences in car ownership.
When experience is gained, people do indeed trust that charging mitigates congestion to a higher extent than they did before: Those that agree that ?congestion charges will decrease [have decreased] the queues to and from the inner-city? is a significantly larger proportion of the population during the Trial, than they were before. Also in accordance with previous results, the attitudes towards the charges became more positive after introduction. This was a continuous process over time, so that attitudes were more positive during the Trial than before, and even more positive after permanent introduction than they were during the Trial. However, the results clearly show that the change in attitudes was much stronger, and continued over a longer period of time, than what could be explained by the learning effect leading to a better understanding of the effects on congestion.
Thus, based on our results, our understanding of which the influential factors are behind the observed effect from experience on attitudes to charging, has to be modified. The mechanisms clearly go beyond ?demonstrating? that charging may effectively mitigate congestion, which is the reason most commonly given in the literature so far.
Our results have important policy implications for which arguments that can be expected to be most effective in building public acceptance for charging, and which subpopulations that are most likely to be influenced by such argumentation.