Allocation of Intrahousehold Motorized Vehicles

Abstract

This study examines allocation of intrahousehold vehicles to drivers and trips by using data from the 2009 National Household Travel Survey and is motivated by the knowledge that reallocating household vehicles is a reasonable short-term action to reduce fuel and associated emissions. Models are developed for households in the national sample and for segmentations by population and census regions. Binomial logistic regression is used to model whether a household fleet is optimal and is a high-potential saver (HPS). Of households with two or more vehicles, 31% are classified as HPS. Linear regression is used to model the number of gallons of fuel a household can potentially save per year with vehicle reallocation. About 59% of households can reduce fuel consumption by an estimated 5.2%, or approximately 5 billion gallons of fuel nationally, if they reallocate their fleet. Household size and life-cycle, travel behavior, and fleet composition are related to allocation of intrahousehold vehicles. Similar variables are significant predictors of potential gallons of savings and whether a household is an HPS. Models are consistent across regions with minor exceptions. Rural areas had differences from more urban areas. This study has demonstrated that appreciable savings in fuel consumption and associated emissions are plausible through vehicle reallocation, and the ability to pursue this countermeasure in the short-term motivates further research to provide fuller understanding of the causal mechanisms and target households for intervention.