Variability of transport emissions and policy implications for the transition towards low-carbon transport

This paper investigates intra-week variability of transport emissions using 2019 English National Travel Survey data. The unique lens of emissions variability sheds new light on the conceptualization, measurement and challenges of sustainable travel. Specifically, our analysis shows significant heterogeneity along three dimensions, (1) intra-week travel emissions; (2) the level and the variability of weekly emissions within each generic socio-economic group; and (3) latent emissions profiles across the population, which are identified using a latent profile model. Our empirical analysis demonstrates that the socio-economic status alone cannot capture the nuanced emission characteristics across traveller groups. The positive correlation between socio-economic status and travel emissions is subject to significant compositional effects. It is argued that transport sustainability is a relative term, and its definition and usefulness in a policy context are dependent on the benchmark selected. The paper calls for a more purposeful and relatable approach for segmenting travellers in designing sustainable travel policies. A dual focus on the level and the variability of travel emissions offers a new perspective for understanding travel behaviour heterogeneity and adaptability.