Do nearby activities result in short trips? Examining the relationship between spatial accessibility and travel behaviour in 15-minute neighbourhoods

Creating 15-minute (15-min) neighbourhoods is crucial for achieving mobility justice, promoting urban vitality, and reducing traffic congestion, air pollution, and energy consumption. However, limited research has examined whether these goals align with current travel behaviour. This paper presents a comprehensive framework for evaluating travel behaviour within 15-min neighbourhoods using mobile phone signalling data and point of interest (POI) data in the central area of Nanjing, China. First, the differences between commuting and non-commuting travel behaviour are analysed. Non-commuting travel behaviour is then used to reveal the relationship between i) the proximity of activities (i.e. spatial accessibility) and ii) travel distance and cumulative travel frequency. The results show that, compared with non-commuting travel, commuting travel has higher travel distances but lower cumulative travel frequencies, with consistently greater variability in both indicators. Within 15-min neighbourhoods, there is no statistically significant correlation between the spatial accessibility of daily service facilities and non-commuting travel distance or cumulative travel frequencies. Furthermore, rose diagram of travel behaviour and accessibility exhibit significantly different spatial distributions. These findings are valuable for informing the planning of 15-min neighbourhoods, as well as for promoting liveability, accessibility and walkability.