Research Publications

Personal transportation accounts for 17 percent of total greenhouse gas emissions in the United States and must be a major component of any climate change mitigation plan. While technological advancements hold promise for improving efficiency and reducing energy consumption uniformly applying the most advanced technology to all vehicles is not cost-effective. A transformational change can be achieved more quickly and at lower cost if the fluctuating and diverse patterns of users’ mobility needs are more closely coupled to the capabilities of available vehicles and fleets. Because requirements for passenger and cargo capacity vary from day to day individuals who rely on a single vehicle typically operate with underutilized capacity leading to higher energy consumption and potentially higher costs. The extent to which the set of options is diversified beyond a single vehicle provides an opportunity for more closely matching trip capacity requirements with vehicle capability.

Using data from the National Household Travel Survey for over 60000 U.S. households an optimization model was applied to analyze two different strategies for reducing energy consumption through capacity matching. With the first strategy vehicles in existing U.S. household fleets were optimally assigned to trips. Average fuel savings in the range from 5 to 23 percent was achieved depending on fleet size and composition. Households with more vehicles in the fleet and a more diverse range of vehicles to choose from are able to achieve higher savings than those with more homogeneous fleets. The second strategy of diversifying vehicle choice sets results in even more significant savings. The extent of savings depends on whether diversification is achieved by changing the composition of existing household fleets adding vehicles to fleets or accessing vehicles outside of the fleet on a temporary basis.