A Review on Energy, Environmental, and Sustainability Implications of Connected and Automated Vehicles (1901.10581v2)

Abstract: Connected and automated vehicles (CAVs) are poised to reshape transportation and mobility by replacing humans as the driver and service provider. While the primary stated motivation for vehicle automation is to improve safety and convenience of road mobility, this transformation also provides a valuable opportunity to improve vehicle energy efficiency and reduce emissions in the transportation sector. Progress in vehicle efficiency and functionality, however, does not necessarily translate to net positive environmental outcomes. Here we examine the interactions between CAV technology and the environment at four levels of increasing complexity: vehicle, transportation system, urban system, and society. We find that environmental impacts come from CAV-facilitated transformations at all four levels, rather than from CAV technology directly. We anticipate net positive environmental impacts at the vehicle, transportation system, and urban system levels, but expect greater vehicle utilization and shifts in travel patterns at the society level to offset some of these benefits. Focusing on the vehicle-level improvements associated with CAV technology is likely to yield excessively optimistic estimates of environmental benefits. Future research and policy efforts should strive to clarify the extent and possible synergetic effects from a systems level in order to envisage and address concerns regarding the short- and long-term sustainable adoption of CAV technology.

• The paper quantifies fuel savings up to 40% at the vehicle level through optimized automation and digitalization.
• The paper reveals that reduced travel costs in shared mobility may inadvertently increase total vehicle miles traveled, offsetting environmental benefits.
• The paper highlights urban transformation by reducing parking and infrastructure needs while cautioning that CAV adoption may trigger unintended urban sprawl.

Energy, Environmental, and Sustainability Implications of Connected and Automated Vehicles

The reviewed paper offers a comprehensive analysis of Connected and Automated Vehicles (CAVs), focusing on the multi-level implications this technology presents for energy efficiency, the environment, and sustainability. The analysis is structured across four system interaction levels: vehicle, transportation system, urban system, and society at large. Through this stratification, the paper makes it evident that CAV technology holds profound potential to reduce transport-related emissions and enhance transportation efficiency. However, it also highlights the intricacies and potential unintended consequences that come with wider CAV adoption.

Key Findings and Implications

1. Vehicle-Level Impacts: At the most fundamental level, CAVs stand to improve energy efficiency markedly. The integration of enhanced digitalization and automation can lead to optimized vehicle operations, reduced idling, smarter route planning, and more efficient driving patterns. Numerical simulations suggest that these efficiencies could result in fuel consumption savings ranging from 2% to 25%, or even as high as 40% under certain conditions. However, the increase in vehicle energy demand due to advanced components like sensors and computing units calls for careful analysis to balance the net energy benefits.
2. Transportation System-Level Effects: CAVs are anticipated to fundamentally alter transportation dynamics by potentially reshaping travel costs and mobility services. While CAVs could substantially reduce travel costs—most notably in shared mobility scenarios—this effect may paradoxically increase total travel demand, potentially offsetting some environmental benefits through increased vehicle miles traveled (VMT). A consistent theme is the outlined potential of CAVs to alleviate congestion and improve overall traffic flow efficiency, although such outcomes depend heavily on CAV penetration rates and adoption of shared-use models.
3. Urban System-Level Changes: The introduction of CAVs is postulated to influence urban infrastructure significantly. Projections suggest a reduction in requirements for traditional transportation infrastructure like parking spaces and traffic lights, potentially enabling more environmentally conscious urban planning and integration of renewable energy sources. Yet, the potential of CAVs to encourage urban sprawl is presented as a counterpoint, warranting further investigation into these dynamics.
4. Societal-Level Implications: On a broad societal scale, CAV adoption could spur shifts in vehicle ownership patterns favoring shared consumption models. With reduced costs of transportation, there is a risk of increased VMT due to additional mobility for currently underserved populations and travel demand elasticity. The dialogue around societal impacts underscores substantial uncertainties tied to behavioral adaptations to CAV technology, which could significantly modulate the ultimate environmental impact.

Research Gaps and Future Directions

The paper recommends a range of future research priorities to robustly capture the energy and environmental impacts of CAVs. Empirical, data-driven studies are advocated to move beyond the speculative framework that presently dominates CAV impact assessments. It also calls for more advanced modeling efforts that consider the complex interplay of factors impacting CAV adoption and utilization, notably under real-world scenarios. Recognizing the significance of behavioral factors, further exploration into consumer acceptance and trip pattern changes with CAVs is critical. The development of supportive policy frameworks that maximize environmental benefits and mitigate adverse consequences is emphasized as an immediate priority.

The integration of CAV technologies is poised to drive substantial transformations across transportation landscapes. Its full potential will only be realized through nuanced understanding and proactive management of both the positive opportunities and the systemic risks. This paper serves as a pivotal foundation for navigating these challenges by framing detailed scenarios and encouraging interdisciplinary collaboration on this evolving front.