UC Davis Institute of Transportation Studies

There has been a general trend to shift the location of warehouses and distribution facilities away from consumer markets (logistics sprawl) in Southern California. This shift has a negative impact on logistics cost (though with reduced facility costs) and the environment because freight vehicles have to travel longer to reach their destinations. However, during the last decade, this trend has not continued at a uniform pace, and it may have even reversed. Two main factors potentially explain this phenomenon: the 2008-2009 economic slow-down or recession, and an increase in e-commerce activity. E-commerce impacts are relevant for freight planning because of the many operational changes they require: changes in vehicle size to distribute smaller shipments at higher frequencies, consumer proximity requirements to improve delivery times, and the redistribution of freight activity and supply chain configurations. This research conducted spatio-temporal analyses of Caltrans Weigh-in-Motion data to validate some of these assumptions. There is evidence that during 2003-2015, short-haul volume has increased by 69%, whereas long-haul volume increased by 59%. The analyses identified changes in concentrations of trip flows by vehicle class, evidencing changes in long-haul versus last-mile distribution patterns. The results can help estimate changes in vehicle miles traveled, and more importantly, can identify the geographical areas of the most impacted communities.