Research Brief: Spatio-Temporal Analysis of Freight Patterns in Southern California

Factors such as the economic recession, the rise of the on-demand economy, changes in the regulatory environment, population growth and urbanization have affected the distribution of goods. One example is the shift in the location of warehouses and distribution facilities away from consumer markets. This shift or logistics sprawl brings about unintended consequences such as increased vehicle miles traveled and concentration of freight activity in specific, usually disadvantaged, communities. In California, especially in Southern California, previous research showed an increase in the concentration of these facilities at longer distances from their primary delivery locations. Additional research also showed that while the trend exists in the region, it has not continued at the same pace in the last decade, or it may have even reversed. The 2008-2009 recession and the growth of e-commerce activity are two of the main factors that potentially explain this phenomenon. These changes are relevant for freight planning because they do not only affect the location of the facilities, but also traffic generation and potential changes in vehicles used. For example, smaller facilities closer to customer may use smaller vehicles distributing smaller shipments at higher frequencies; or, the redistribution of the freight activity and supply chain configurations. This research brief summarizes findings from the project which used the California Department of Transportation Weigh-in-Motion data from stations located in Southern California from January 2003 to December 2015 to validate some of these assumptions.