Do hard traffic measures produce hard changes? A case study of individuals’ changing mobility behaviour and environmental concern following the implementation of a modal filter in Aachen, Germany

In the transition to sustainable mobility, many cities aim to reduce motorised transport and promote active modes of travel. In June 2021, the city of Aachen, Germany, together with citizen and student associations closed a section of the inner-city ring street ‘Templergraben’ to individual motorised transport (IMT) by implementing a modal filter for IMT through traffic as a ‘hard measure’. The street section and its surrounding infrastructure were transformed into a living lab. This paper aims to assess the impact of the hard measure on individuals’ mobility behaviour as pro-environmental behaviour (PEB) in relation to their environmental concern (EC). We conducted a survey (N = 1243) in autumn 2021 to measure the respondents’ acceptance of the modal filter, their EC, and their mobility behaviour. We operationalise cost through transport equity and perform various linear regression models to enable empirical validation of the low-cost hypothesis within high-cost subgroups. Our findings demonstrate how inequitable burdens disrupt the connection between environmental concern, acceptance of a modal filter, and PEB in high-cost mobility situations. We conclude that hard measures alone fail to induce PEB in high-cost contexts, but equity-centred soft measures could facilitate the translation of EC into PEB via increased acceptance.