Behavioural interventions change transport behavior but have only a limited impact on transport mode split

Prevalent systems of land transport, centred around automobility, are energy inefficient and involve high economic, health and GHG emissions-related costs. As one class of solutions, demand-side behavioural change interventions (or soft policy interventions) are promoted to reduce car use and shift travellers to low-carbon transport modes. However, the relative effectiveness of such interventions in initiating transport behaviour change has not been evaluated systematically. Here, we conduct a systematic review and meta-analysis to evaluate the evidence on behavioural interventions in changing transport-related behavioural patterns. Relying on 37 literature reviews and 41 additional new studies, we identify more than 450 cases of behavioural interventions. Our analysis reveals that behavioural measures are effective in increasing the percentage growth of public transit and active transport mode use as well as decreasing car use at the personal level. However, their effectiveness in shifting commuters away from cars to more sustainable modes of transport at the aggregate level is limited. Our findings suggest that behavioural interventions have a role to play in reducing the health, economic and environmental costs of car-centric transportation systems. We find that, under the best-case scenario, behavioural interventions can contribute up to a 5% per cent reduction of global GHG emissions from urban transport, or about 150Mt CO2/yr, a notable but limited potential compared to the reductions necessary to meet sectoral goals. Critical analysis of studies in our review indicates that interdisciplinary researchers interested in these issues should take a more strategic and rigorous approach—better study designs, more representative samples, and consideration of infrastructure effects—to determine which interventions are most effective in tackling multi-faceted urban transport issues.