Associations between tree characteristics and street crime: A case study in downtown Austin, TX

Abstract

Urban trees play a critical role in livable and safe communities. Few studies have attempted to comprehensively examine a set of tree-related characteristics by using multiple measures through aerial imagery, street view imagery, and tree inventories in relation to street crime, especially in downtowns with busy street activities. This study examined to what extent tree attributes were associated with street crime at the street segment scale. This study also aimed to investigate the relationships of proxy measures for view-obstructive levels of trees with street crimes. Using downtown Austin, Texas as a study area, we analyzed micro-level crime incidents at a street segment level: 518 street segments in total within the downtown neighborhood. We used violent and property crime incidents that occurred on the streets between 2014 and 2019. A series of negative binomial regressions were employed to explore the associations of the characteristics of trees with street crime. After adjusting for socioeconomic and built environment variables, tree canopy coverage using aerial imageries and tree coverage using Google Street View images had inverse relationships with both violent and property street crime rates while size-weighted tree density using tree inventory was only associated with violent street crime rate. The tree coverage in the bottom-half of GSV images was inversely associated with violent street crime rate but not with property street crime rate. Additionally, we found that large-sized tree density (DBH≥30 cm and 40 cm) was inversely associated with both types of crime rates while small-sized tree density (DBH≤20 cm) was positively associated with property crime rate. While further research is needed to validate the view-obstructing effects of small-sized tree density and tree coverage in the bottom-half of GSV images, it is important to consider factors such as appropriate tree size and the potential for view-obstruction to maximize the benefits of urban trees in crime prevention.