Expert Commentary

Cruising into a driverless future: Research on autonomous vehicles

This research roundup looks at automated vehicles, including findings on potential benefits, safety concerns, public opinion and policy implications.

cars on overpass

Eerie as it may seem to drive alongside a car with no one behind the wheel, autonomous vehicles are poised to hit the roads in the next few years. A lawsuit between Uber and Waymo, Google’s self-driving car project, settled in February 2018 illustrates the fierce battle to develop driverless car technology. Many cars already employ semi-autonomous technology, such as parking assistance and lane monitoring.

The National Highway Traffic Safety Administration (NHTSA) suggests that automated vehicles could promote safety on the road. According to the NHTSA’s Federal Automated Vehicles Policy, 94 percent of car accidents are linked to human choice or error. Automated vehicles, the NHTSA writes, could reduce the frequency of crashes by eliminating some human error on the roads. The policy indicates positive features of automated vehicles beyond safety, including potential environmental benefits and increased mobility for those otherwise unable to drive.

The cutting-edge technology, however, presents ethical questions and other concerns. Some research included in this roundup indicates that the environmental effects of widespread adoption of autonomous vehicles might not be positive. Safety benefits are not so clear-cut either. This roundup brings together this scholarship along with other related research, including findings on public opinion and policy implications.


Potential benefits

Estimating Potential Increases in Travel with Autonomous Vehicles for the Non-Driving, Elderly and People with Travel-Restrictive Medical Conditions
Harper, Corey D.; Hendrickson, Chris T.; Mangones, Sonia; Samaras, Constantine. Transportation Research Part C: Emerging Technologies, 2016. DOI: 10.1016/j.trc.2016.09.003.

Abstract: “Automated vehicles represent a technology that promises to increase mobility for many groups, including the senior population (those over age 65) but also for non-drivers and people with medical conditions. This paper estimates bounds on the potential increases in travel in a fully automated vehicle environment due to an increase in mobility from the non-driving and senior populations and people with travel-restrictive medical conditions.”

Sustainability Implications of Connected and Autonomous Vehicles for the Food Supply Chain
Heard, Brent R.; Taiebat, Morteza; Xu, Ming; Miller, Shelie A. Resources, Conservation & Recycling, 2018. DOI: 10.1016/j.resconrec.2017.09.021.

Abstract: “Connected and autonomous vehicles are anticipated to transform food distribution systems. The food distribution industry is a likely early-adopter of this technology, with resulting changes affecting the environmental and economic profiles of the food supply chain. Considerations for a truly sustainable adoption of this technology are discussed.”

 “Autonomous Vehicles: The Next Jump in Accessibilities?
Meyer, Jonas; Becker, Henrik; Bösch, Patrick M.; Axhausen, Kay W. Research in Transportation Economics, 2017. DOI: 10.1016/j.retrec.2017.03.005.

Abstract: “Autonomous vehicles are expected to offer a higher comfort of traveling at lower prices and at the same time to increase road capacity – a pattern recalling the rise of the private car and later of motorway construction. Using the Swiss national transport model, this research simulates the impact of autonomous vehicles on accessibility of the Swiss municipalities. The results show that autonomous vehicles could cause another quantum leap in accessibility. Moreover, the spatial distribution of the accessibility impacts implies that autonomous vehicles favor urban sprawl and may render public transport superfluous except for dense urban areas.”

Automated Vehicles, On-Demand Mobility, and Environmental Impacts
Greenblatt, Jeffery B.; Shaheen, Susan. Current Sustainable/Renewable Energy Reports, 2015. DOI: 10.1007/s40518-015-0038-5.

Abstract: “We review the history, current developments, projected future trends and environmental impacts of automated vehicles (AVs) and on-demand mobility, and explore potential synergies. Many automobile manufacturers and Google plan to release AVs between 2017 and 2020, with potential benefits including increased safety, more efficient road use, increased driver productivity and energy savings. Estimates of AV energy use and greenhouse gas (GHG) emissions range from an ~80 percent or greater decrease to a threefold increase; however, we argue that net decreases are likely. On-demand mobility services exist in many cities around the world, with advances in mobile technology increasing their popularity. On-demand mobility can provide numerous transportation, land use, and environmental and social benefits, and users tend to decrease both vehicle ownership and annual vehicle distances traveled. Combining on-demand mobility and AVs may amplify adoption of both, and further lower energy use and GHG emissions through the use of small, efficient shared AVs.”

Help or Hindrance? The Travel, Energy and Carbon Impacts of Highly Automated Vehicles
Wadud, Zia; MacKenzie, Don; Leiby, Paul. Transportation Research Part A: Policy and Practice, 2016. DOI: 10.1016/j.tra.2015.12.001.

Abstract: “Experts predict that new automobiles will be capable of driving themselves under limited conditions within 5–10 years, and under most conditions within 10–20 years. Automation may affect road vehicle energy consumption and greenhouse gas (GHG) emissions in a host of ways, positive and negative, by causing changes in travel demand, vehicle design, vehicle operating profiles, and choices of fuels. In this paper, we identify specific mechanisms through which automation may affect travel and energy demand and resulting GHG emissions and bring them together using a coherent energy decomposition framework. We review the literature for estimates of the energy impacts of each mechanism and, where the literature is lacking, develop our own estimates using engineering and economic analysis. We consider how widely applicable each mechanism is, and quantify the potential impact of each mechanism on a common basis: the percentage change it is expected to cause in total GHG emissions from light-duty or heavy-duty vehicles in the U.S. Our primary focus is travel related energy consumption and emissions, since potential lifecycle impacts are generally smaller in magnitude. We explore the net effects of automation on emissions through several illustrative scenarios, finding that automation might plausibly reduce road transport GHG emissions and energy use by nearly half — or nearly double them — depending on which effects come to dominate. We also find that many potential energy-reduction benefits may be realized through partial automation, while the major energy/emission downside risks appear more likely at full automation. We close by presenting some implications for policymakers and identifying priority areas for further research.”


Ethical questions

“The Ethics of Accident-Algorithms for Self-Driving Cars: An Applied Trolley Problem?
Nyholm S.; Smids J. Ethical Theory and Moral Practice, 2016. DOI: 10.1007/s10677-016-9745-2.

Abstract: “Self-driving cars hold out the promise of being safer than manually driven cars. Yet they cannot be 100 percent safe. Collisions are sometimes unavoidable. So self-driving cars need to be programmed for how they should respond to scenarios where collisions are highly likely or unavoidable. The accident-scenarios self-driving cars might face have recently been likened to the key examples and dilemmas associated with the trolley problem. In this article, we critically examine this tempting analogy. We identify three important ways in which the ethics of accident-algorithms for self-driving cars and the philosophy of the trolley problem differ from each other. These concern: (i) the basic decision-making situation faced by those who decide how self-driving cars should be programmed to deal with accidents; (ii) moral and legal responsibility; and (iii) decision-making in the face of risks and uncertainty. In discussing these three areas of disanalogy, we isolate and identify a number of basic issues and complexities that arise within the ethics of the programming of self-driving cars.”

The Social Dilemma of Autonomous Vehicles
Bonnefon J.F.; Shariff A.; Rahwan I. Science, 2016. DOI: 10.1126/science.aaf2654.

Abstract: “Autonomous vehicles (AVs) should reduce traffic accidents, but they will sometimes have to choose between two evils, such as running over pedestrians or sacrificing themselves and their passenger to save the pedestrians. Defining the algorithms that will help AVs make these moral decisions is a formidable challenge. We found that participants in six Amazon Mechanical Turk studies approved of utilitarian AVs (that is, AVs that sacrifice their passengers for the greater good) and would like others to buy them, but they would themselves prefer to ride in AVs that protect their passengers at all costs. The study participants disapprove of enforcing utilitarian regulations for AVs and would be less willing to buy such an AV. Accordingly, regulating for utilitarian algorithms may paradoxically increase casualties by postponing the adoption of a safer technology.”



Driving to Safety: How Many Miles of Driving Would it Take to Demonstrate Autonomous Vehicle Reliability?
Kalra, Nidhi; Paddock, Susan M. Transportation Research Part A: Policy and Practice, 2016. DOI: 10.1016/j.tra.2016.09.010.

Abstract: “How safe are autonomous vehicles? The answer is critical for determining how autonomous vehicles may shape motor vehicle safety and public health, and for developing sound policies to govern their deployment. One proposed way to assess safety is to test drive autonomous vehicles in real traffic, observe their performance, and make statistical comparisons to human driver performance. This approach is logical, but it is practical? In this paper, we calculate the number of miles of driving that would be needed to provide clear statistical evidence of autonomous vehicle safety. Given that current traffic fatalities and injuries are rare events compared to vehicle miles traveled, we show that fully autonomous vehicles would have to be driven hundreds of millions of miles and sometimes hundreds of billions of miles to demonstrate their reliability in terms of fatalities and injuries. … These findings demonstrate that developers of this technology and third-party testers cannot simply drive their way to safety. Instead, they will need to develop innovative methods of demonstrating safety and reliability. And yet, the possibility remains that it will not be possible to establish with certainty the safety of autonomous vehicles. Uncertainty will remain. Therefore, it is imperative that autonomous vehicle regulations are adaptive — designed from the outset to evolve with the technology so that society can better harness the benefits and manage the risks of these rapidly evolving and potentially transformative technologies.”

Is Partially Automated Driving a Bad Idea? Observations from an On-Road Study
Banks, Victoria A.; Eriksson, Alexander; O’Donoghue, Jim; Stanton, Neville A. Applied Ergonomics, 2018. DOI: 10.1016/j.apergo.2017.11.010.

Abstract: “The automation of longitudinal and lateral control has enabled drivers to become ‘hands and feet free’ but they are required to remain in an active monitoring state with a requirement to resume manual control if required. This represents the single largest allocation of system function problem with vehicle automation as the literature suggests that humans are notoriously inefficient at completing prolonged monitoring tasks. To further explore whether partially automated driving solutions can appropriately support the driver in completing their new monitoring role, video observations were collected as part of an on-road study using a Tesla Model S being operated in Autopilot mode. A thematic analysis of video data suggests that drivers are not being properly supported in adhering to their new monitoring responsibilities and instead demonstrate behavior indicative of complacency and over-trust. These attributes may encourage drivers to take more risks whilst out on the road.”

Autonomous Vehicles’ Disengagements: Trends, Triggers, and Regulatory Limitations
Favarò, Francesca; Eurich, Sky; Nader, Nazanin. Accident Analysis & Prevention, 2018. DOI: 10.1016/j.aap.2017.11.001.

Abstract: “Autonomous Vehicle (AV) technology is quickly becoming a reality on U.S. roads. Testing on public roads is currently undergoing, with many AV makers located and testing in Silicon Valley, California. The California Department of Motor Vehicles (CA DMV) currently mandates that any vehicle tested on California public roads be retrofitted to account for a back-up human driver, and that data related to disengagements of the AV technology be publicly available. Disengagements data is analyzed in this work, given the safety-critical role of AV disengagements, which require the control of the vehicle to be handed back to the human driver in a safe and timely manner. This study provides a comprehensive overview of the fragmented data obtained from AV manufacturers testing on California public roads from 2014 to 2017. Trends of disengagement reporting, associated frequencies, average mileage driven before failure, and an analysis of triggers and contributory factors are here presented. The analysis of the disengagements data also highlights several shortcomings of the current regulations. The results presented thus constitute an important starting point for improvements on the current drafts of the testing and deployment regulations for autonomous vehicles on public roads.”

Examining Accident Reports Involving Autonomous Vehicles in California
Favarò, F.M.; et al. PLoS ONE, 2017. DOI: 10.1371/journal.pone.0184952.

Abstract: “Autonomous Vehicle technology is quickly expanding its market and has found in Silicon Valley, California, a strong foothold for preliminary testing on public roads. In an effort to promote safety and transparency to consumers, the California Department of Motor Vehicles has mandated that reports of accidents involving autonomous vehicles be drafted and made available to the public. The present work shows an in-depth analysis of the accident reports filed by different manufacturers that are testing autonomous vehicles in California (testing data from September 2014 to March 2017). The data provides important information on autonomous vehicles accidents’ dynamics, related to the most frequent types of collisions and impacts, accident frequencies, and other contributing factors. The study also explores important implications related to future testing and validation of semi-autonomous vehicles, tracing the investigation back to current literature as well as to the current regulatory panorama.”


Public opinion

Assessing Public Opinions of and Interest in New Vehicle Technologies: An Austin Perspective
Bansal, Prateek; Kockelman, Kara M.; Singh, Amit. Transportation Research Part C: Emerging Technologies, 2016. DOI: 10.1016/j.trc.2016.01.019.

Abstract: “Technological advances are bringing connected and autonomous vehicles (CAVs) to the ever-evolving transportation system. Anticipating public acceptance and adoption of these technologies is important. A recent internet-based survey polled 347 Austinites to understand their opinions on smart-car technologies and strategies. Results indicate that respondents perceive fewer crashes to be the primary benefit of autonomous vehicles (AVs), with equipment failure being their top concern. Their average willingness to pay (WTP) for adding full (Level 4) automation ($7,253) appears to be much higher than that for adding partial (Level 3) automation ($3,300) to their current vehicles.”

Public Opinion on Automated Driving: Results of an International Questionnaire Among 5,000 Respondents
Kyriakidis, M.; Happee, R.; de Winter, J.C.F. Transportation Research Part F: Traffic Psychology and Behaviour, 2015. DOI: 10.1016/j.trf.2015.04.014.

Abstract: “This study investigated user acceptance, concerns, and willingness to buy partially, highly, and fully automated vehicles. By means of a 63-question Internet-based survey, we collected 5,000 responses from 109 countries (40 countries with at least 25 respondents). We determined cross-national differences, and assessed correlations with personal variables, such as age, gender, and personality traits as measured with a short version of the Big Five Inventory. Results showed that respondents, on average, found manual driving the most enjoyable mode of driving. Responses were diverse: 22 percent of the respondents did not want to pay more than $0 for a fully automated driving system, whereas 5 percent indicated they would be willing to pay more than $30,000, and 33 percent indicated that fully automated driving would be highly enjoyable. 69 percent of respondents estimated that fully automated driving will reach a 50 percent market share between now and 2050. Respondents were found to be most concerned about software hacking/misuse, and were also concerned about legal issues and safety. Respondents scoring higher on neuroticism were slightly less comfortable about data transmitting, whereas respondents scoring higher on agreeableness were slightly more comfortable with this. Respondents from more developed countries (in terms of lower accident statistics, higher education, and higher income) were less comfortable with their vehicle transmitting data, with cross-national correlations between ρ = −0.80 and ρ = −0.90. The present results indicate the major areas of promise and concern among the international public, and could be useful for vehicle developers and other stakeholders.”

Autonomous Vehicles and Alternatives to Driving: Trust, Preferences, and Effects of Age
Abraham, Hillary; et al. Paper presented at Transportation Research Board Annual Meeting, 2017.

Abstract: “New vehicle technologies and transportation alternatives offer the potential of expanded mobility solutions for users of all generations. While many industries are focused on creating these options, only limited research has explored their use, adoption, and appeal as they apply to older generations. An online survey was fielded in order to gather information on satisfaction with current in-vehicle technology, inclination to use differing levels of automation, transportation alternatives to driving your own car, and methods of learning to use in-vehicle technology across users of all ages. The survey found that respondents reported generally being satisfied with technology in their vehicles, but are not learning to use the systems with their preferred methods of learning. A majority of respondents indicated a willingness to consider transportation alternatives, but far fewer had taken advantage of the alternatives in the past year. Older adult respondents, in particular, are not taking advantage of new mobility solutions at the levels that they might. Finally, while many older adults generally expressed a willingness to use some level of automation, they expressed less interest in full autonomy than younger drivers.”


Long-term implications

Preparing a Nation for Autonomous Vehicles: Opportunities, Barriers and Policy Recommendations
Fagnant, Daniel J.; Kockelman, Kara. Transportation Research Part A: Policy and Practice, 2015. DOI: 10.1016/j.tra.2015.04.003.

Abstract: “Autonomous vehicles (AVs) represent a potentially disruptive yet beneficial change to our transportation system. This new technology has the potential to impact vehicle safety, congestion, and travel behavior. All told, major social AV impacts in the form of crash savings, travel time reduction, fuel efficiency and parking benefits are estimated to approach $2,000 to per year per AV, and may eventually approach nearly $4,000 when comprehensive crash costs are accounted for. Yet barriers to implementation and mass-market penetration remain. Initial costs will likely be unaffordable. Licensing and testing standards in the U.S. are being developed at the state level, rather than nationally, which may lead to inconsistencies across states. Liability details remain undefined, security concerns linger, and without new privacy standards, a default lack of privacy for personal travel may become the norm. The impacts and interactions with other components of the transportation system, as well as implementation details, remain uncertain. To address these concerns, the federal government should expand research in these areas and create a nationally recognized licensing framework for AVs, determining appropriate standards for liability, security, and data privacy.”

Policy and Society Related Implications of Automated Driving: A Review of Literature and Directions for Future Research
Milakis, Dimitris; van Arem, Bart; van Wee, Bert. Journal of Intelligent Transportation Systems, 2017. DOI: 10.1080/15472450.2017.1291351.

Abstract: “In this paper, the potential effects of automated driving that are relevant to policy and society are explored, findings discussed in literature about those effects are reviewed and areas for future research are identified. The structure of our review is based on the ripple effect concept, which represents the implications of automated vehicles at three different stages: first-order (traffic, travel cost, and travel choices), second-order (vehicle ownership and sharing, location choices and land use, and transport infrastructure), and third-order (energy consumption, air pollution, safety, social equity, economy, and public health). Our review shows that first-order impacts on road capacity, fuel efficiency, emissions and accidents risk are expected to be beneficial. The magnitude of these benefits will likely increase with the level of automation and cooperation and with the penetration rate of these systems. The synergistic effects between vehicle automation, sharing and electrification can multiply these benefits. However, studies confirm that automated vehicles can induce additional travel demand because of more and longer vehicle trips. Potential land use changes have not been included in these estimations about excessive travel demand. Other third-order benefits on safety, economy, public health and social equity still remain unclear. Therefore, the balance between the short-term benefits and long-term impacts of vehicle automation remains an open question.”

Assessing the Long-term Effects of Autonomous Vehicles: A Speculative Approach
Gruel, Wolfgang; Stanford, Joseph M. Transportation Research Procedia, 2016. DOI: 10.1016/j.trpro.2016.05.003.

Abstract: “In recent years, self-driving cars have generated significant attention and discussion. While it is recognized that a number of technical and legal issues need to be solved, widespread adoption of self-driving vehicles is increasingly considered to be inevitable. However, the long-term effects of this technology are rarely considered and seldom examined in the literature. Among these potential impacts are a number of direct and indirect, positive and negative outcomes, and the net effect in terms of societal benefit or harm is far from clear. In this paper, we identify the several of these outcomes, and we explore conditions in the broader transportation system under which self-driving vehicles may be either harmful or beneficial. We investigate how autonomous operation could affect the attractiveness of traveling by car, how this in turn could affect mode choice, and how changes in mode choice would affect the broader transportation system. The paper considers three speculative scenarios, defined primarily by different behavioral responses to the availability of autonomous driving. The scenarios build on an established system dynamics model that represents the major forces involved in transportation systems. A wide range of outcomes are considered, and potential policy interventions are discussed.”


If you’re interested in reading more research on transportation, we have written about distracted driving, road congestion, the effects of changing gas prices and the impact of laws that prohibit texting while driving.

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