Diverging roads: A panel analysis on motorisation rates in German counties from 2012 to 2022

Abstract

Motorisation rates have continued to increase in most countries. Existing studies on motorisation rates are mainly cross-sectional, offering limited insight into changes over time. However, understanding these changes is crucial for developing sustainable transport strategies.

This study addresses this limitation by analysing panel data on motorisation rates (private cars/1000 residents) in German counties from 2012 to 2022. We use fixed-effects models to examine how changes within counties over time are associated with changes in motorisation rates and between-effects models to assess how differences across counties relate to motorisation rates. This approach provides insights into both dynamic changes and long-standing differences between counties while evaluating the transferability of cross-sectional findings for understanding dynamic processes. Moreover, we stratify the analysis according to different county characteristics (location, type of region, median household income and public transport accessibility).

The results indicate complex associations between county characteristics and motorisation rates. The factors associated with motorisation rates across counties show different associations when looking at changes within counties over time. In some cases, such as the share of young adults, the associations are even opposite. These associations also vary between more and less car-dependent counties. For instance, increasing population density is associated with decreasing motorisation rates only within urban regions, and an increasing share of elderly adults is associated with increasing motorisation rates within urban regions but with declining motorisation rates in rural regions.

Our findings caution against generalising from cross-sectional data and emphasise the need for tailored strategies for different areas. In doing so, they highlight the crucial role of sub-national, longitudinal analyses in understanding the dynamics of motorisation.