Institute of Transport Research, German Aerospace Center

This paper, for the first time, presents comparable projections of travel behavior impacts of the introduction of autonomous vehicles (AVs) into the private car fleet for two countries, namely the USA and Germany. The focus is on fully autonomous vehicles (AVs) which allow drivers to engage in other activities en route. Two 2035 scenarios – a trend scenario and an extreme scenario – are presented for both study countries. For these projections, we combine a vehicle technology diffusion model and an aspatial travel demand model. Factors that influence AV impact in the behavioral model are mainly new automobile user groups, e.g. travelers with mobility impairments, and altered generalized costs of travel, e.g. due to a lower value of travel time savings for car travel. The results indicate that AV penetrations rates might be higher in Germany (10% or 38% respectively) than in the USA (8% or 29% respectively) due to a higher share of luxury cars and quicker fleet turnover. On the contrary, the increase of vehicle mileage induced by AVs is not higher in Germany (+2.4% or +8.6% respectively) than in the USA (+3.4% or +8.6% respectively). This is mainly due to the lack of mode alternatives and lower fuel costs resulting in a higher share of travel times among the total generalized costs of travel in the USA. These results clearly indicate that context factors shaped by national policy will influence AV adoption and impact on travel demand changes. Based on these results the paper draws policy recommendations which will help to harness the advantages of AVs while avoiding their negative consequences.

Over the past few years, many studies have provided detailed descriptions of the potential benefits associated with the introduction of autonomous vehicles, such as improvements in traffic flows, local and global emissions, traffic safety, cost efficiency of public and private transport operations, etc. Additionally, the mobilization of mobility-impaired people and the independent car use of travelers without a driver’s license have been identified as potential benefits for users. However, merely estimating the benefits of these direct (or first-order) effects is unlikely to show the full picture of the consequences that will emerge once autonomous vehicles enter the roads. In this paper, we therefore put emphasis on discussing systemic (or second-order) effects. The paper presents a conceptual exploration of these effects based on literature and research findings to date. We show that these systemic effects have the potential – especially in urban areas and without adequate policy intervention – to eliminate at least some of the benefits initially associated with autonomous vehicles. Following this systemic view on autonomous vehicles, we discuss policy aspects for responsible authorities and planners on how to prepare transportation systems for the challenges related to the introduction of autonomous vehicles, and conclude with areas of research that seem highly important in terms of further investigation in this context.