Public perceptions of 30 km/h speed limits and their implications for liveability: a two-stage approach combining factor analysis and latent variable random parameter models

This study investigates public attitudes toward 30 km/h (20mph) speed limits in urban areas and their liveability dimensions. It specifically examines two key aspects: (i) the public acceptance of the policy; and (ii) perceived impacts on city-centre liveability. A two-stage integrated modelling framework was developed and adopted. First, latent attitudinal factors underlying public perceptions were extracted through Exploratory Factor Analysis (EFA). Second, these latent factors, alongside observed socio-demographic and travel characteristics, were incorporated into advanced random parameter models with heterogeneity in the means: an ordered probit model for policy acceptance, and a bivariate probit model for jointly analysing city-centre attractiveness for living and working. Focusing on Greece, where a default 30 km/h speed limit was recently introduced, the empirical results showed that latent factors relating to safety, sustainable travel, driving behavior, and urban accessibility, alongside socio-demographic characteristics and travel habits, shape policy acceptance. Expectations for enhanced road safety, sustainable mobility, and improved neighbourhood accessibility are strong determinants of public support. Conversely, perceived implementation barriers, low-speed driving frustration, and environmental scepticism reduce acceptance. Socio-demographic characteristics, including education, age, gender, and residential context, are found to mediate the impact of attitudinal factors on public support. The bivariate probit model reveals distinct determinants for perceived city-centre attractiveness for living versus working. While safety and sustainable travel consistently matter, environmental attitudes, household composition, and employment sector exert differential effects. Overall, public attitudes surrounding the 30 km/h policy are driven by road safety considerations alongside broader expectations related to quality of life, urban functionality, and liveability.