Spatiotemporal Analysis of Macroscopic Patterns of Urbanization and Traffic Safety: A Case Study in Sacramento County, California

This study provides a preliminary investigation into the relationship between urbanization and trafficcollisions by analyzing the spatial patterns in Sacramento County, California from 1998 to 2008 using urban land classifications and traffic collision data. The ArcGIS directional distribution tool was used to create standard deviational ellipses to investigate the distributional trend of urban land and traffic collisions over time. Statistical outputs representing changes of geographical centroids, elliptical areas, and standard distances (long and short axes) were then compared. Collisions were also subset by severity level to account for inherent differences in the spatial distribution of different types of collisions. The results provided insight into the macroscopic spatial patterns of urban land and traffic safety and their relationships. The limitations of the method and the need for further research were discussed. The approach in this study would be useful for other metropolitan areas with similarly changing development patterns and can be helpful in guiding future research comparing these two phenomena.