Traditionally when we think of the environmental cost of autonomous vehicles we think in largely positive terms.  Autonomous cars will be able to drive more fuel efficiently than humans, which will lower the carbon footprint of car travel.

Research from the University of Wisconsin-Madison isn’t quite so optimistic, and suggests that autonomous driving will have a significant environmental cost.

The study focuses particularly on the uses of autonomous vehicles and the competition that might arise with other modes of transport.  The results suggest that because autonomous transport will pull in passengers from less carbon-intensive transportation options, it will raise the overall impact of travel.

Costs and benefits

Supporters of the technology argue that it will deliver significant benefits in terms of accessibility and safety of transport.  The researchers argue, however, that these benefits may simply mask the environmental impacts that may accrue.

This impact is in large part due to the behavior changes that may accompany the arrival of the technology.  The researchers examine these changes in terms of greenhouse gas emissions, pollutants, energy consumption, and particulates.

The researchers examined our attitudes towards various modes of transport to understand how we decide what form we would take for any particular journey.  This revealed that autonomous taxis would be used for 31% of journeys due to their desirable characteristics.  Buses and other forms of public transport fared particularly badly in this decision making, with personal vehicles somewhere in between.

Personal owernship

This was far less likely for those who owned a personal vehicle, however, as such people would be far less likely to choose an autonomous vehicle.  This, the researchers argue, suggests that autonomous vehicles are primarily competing with public transport.

As such, any policies that are designed to reduce the amount we commute in our own vehicles might not be that successful in reducing the environmental impact of our commute.

After the surveys, the researchers conducted a number of simulations, all of which confirmed that autonomous vehicles were primarily competing with buses, which are, of course, the most environmentally friendly mode of transport.  The simulations also showed that any fall in bus travel times would also result in a spike in bus usage.

Offsetting the cost

To offset the environmental cost of autonomous vehicles, the researchers proposed the use of purely electric vehicles.  This appeared to have a significant impact, providing of course that the electricity was generated in a clean way, and that the adoption of them was over 40% or so.

The authors hope that their work will help both policymakers and researchers alike understand the impact of autonomous vehicles on the environment before proceeding with attempts to encourage the rollout of the technology.  They believe that as cities roll out the technology, it’s important that they seek to both match consumer adoption patterns while also doing so in an environmentally beneficial way.

“The transportation system is on the verge of a major paradigm shift,” the researchers conclude. “Emerging technologies as autonomous and electric vehicles, along with change in commuting behavior will have significant operational and environmental impacts. It is of crucial importance that we consider those impacts conjointly, if we are to forge an efficient and sustainable mobility of the future.”