Meta-analyses on Perceived Effectiveness Ratings and Public Acceptability of Road Pricing
Christiane Kramer, Technische Universität Dresden, Jens Schade, Technische Universität Dresden
Meta-analyses allow quantifying the size and effective direction of correlations between perceived effectiveness ratings and public acceptability of RP. The results sum up the current state of knowledge and may help improve policy development.
Managing traffic in urban areas to reduce traffic congestion and the detrimental environmental effects of traffic has long been on the agenda of industrialized countries. Road pricing (RP) has been considered by many, but only few countries have taken the step to introduce it. The reasons are manifold, but public opposition and with it the political reluctance to even seriously discuss the matter plays a vital role.
Only few theoretical models exist that try to explain the determinants of public acceptability toward RP and their interrelations. Based on Ajzen’s Theory of Planned Behavior, Schade derived a model of psychological determinants of public acceptability toward RP. This model is used as a theoretical basis for the meta-analyses described here. A number of determinants may be considered, among them problem awareness, perceived effectiveness of RP to solve the problems, and social norms.
The perceived effectiveness of RP measures to achieve beneficial traffic-related effects is often considered to be one of the most important predictors to gain public acceptability of such measures. If RP is perceived to be effective e.g. to reduce environmental pollution, or to affect mobility behavior, research so far finds moderate or even high size positive correlations with acceptability. However, a final assessment on the association of perceived effectiveness ratings and acceptability is still lacking.
This paper presents the results of meta-analyses that examine the summary correlations of perceived effectiveness and acceptability of RP. Published and non-published primary studies in three languages and from a number of countries were identified and their effect sizes summarized. Meta-analyses are conducted for six variables:
Perceived effectiveness to reduce…
• environmental pollution
• traffic congestion
• noise, and
• own car use.
In addition, perceived effectiveness to…
• improve traffic safety
• affect other people’s mobility behavior.
The meta-analyses encompass three to fifteen primary study effect sizes. The results show summary correlations in the hypothesized direction. In five of the six cases moderate positive mean correlations are found, meaning that high perceived effectiveness ratings are associated with high acceptability ratings.
A small positive correlations is found for the association between perceived effectiveness to reduce own car use and acceptability.
For perceived effectiveness to reduce environmental pollution a moderating effect is found, i.e. the strength of the mean correlation is influenced by whether the RP scheme in question is in operation or not at the time of the survey.
The results support the assumptions in traffic psychology to date. Moderator effects are exerting an influence though. The meta-analyses underpin moderate positive correlations between acceptability of RP and several perceived effectiveness ratings. Thus, demonstrating the effectiveness of such measures may improve public acceptability, if this association is directional. Note, that the meta-analyses are calculated on correlations which makes it impossible to identify the effective direction of the association.
The analyses are carried out as part of a PhD-work that aims at conducting extensive meta-analyses on psychological variables, mobility-related variables, and socio-economic variables, and their association with public acceptability.
Association for European Transport