Contribution of Automated Vehicles to Reduced Fuel Consumption and Air Pollution
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Contribution of Automated Vehicles
to Reduced Fuel Consumption
and Air Pollution
November 2013
PREPARED FOR
Tampa Hillsborough Expressway Authority
PREPARED BY
Jochen Eckart and Kala Vairavamoorthy
Patel College of Global Sustainability
University of South Florida
Disclaimer
The contents of this report reflect the views of the authors, who are responsible for the facts
and the accuracy of the information presented herein.
The opinions, findings, and conclusions expressed in this publication are those of the
authors and not necessarily those of the State of Florida Department of Transportation or
the Tampa Hillsborough Expressway Authority (THEA).
iiContribution of Automated Vehicles to
Reduced Fuel Consumption and Air Pollution
PREPARED FOR
Tampa Hillsborough Expressway Authority
PREPARED BY
Jochen Eckart and Kala Vairavamoorthy
Patel College of Global Sustainability
University of South Florida
November 2013
iiiAbstract
An analysis evaluating the Strengths, Weaknesses, Opportunities, and Threats (SWOT) of
automated vehicles for reducing fuel consumption and promoting alternative fuels
technologies is provided. The SWOT analysis looks at two scales—a single automated
vehicle and the overall traffic system. Automated vehicles (AVs) themselves provide
significant safety benefits, may improve urban core areas by reducing the need for parking,
and hold a lot of strength in promoting fuel reduction and providing synergies with
alternative fuel vehicles. A reduction of fuel consumption of 20 to 50 percent seems to be
possible. Nevertheless, on the scale of the entire traffic system, there are both opportunities
to improve fuel efficiency and the rebound effects resulting in an increased number of
vehicle miles of travel (VMT). Combining the different opportunities and threats, the impacts
range from a fuel reduction of 20 percent to an increase of fuel consumption of 50 percent.
Automated vehicles provide the potential to reduce fuel consumption, but it is far from
certain that this goal is actually achieved.
Introduction
The transport sector accounts for 70 percent of petroleum consumption in the U.S. and is
the cause of significant greenhouse gas emission and local air pollution. To reduce the
consumption of petroleum-based fuels and to address air pollution in the Tampa Bay region,
current efforts are underway by the Tampa Bay Clean Cities Coalition (TBCCC). TBCCC
embraces the use of non-petroleum-based transportation fuels, thereby leading to improved
health and welfare for its citizens by maintaining a level of mobility that enhances the
overall quality of life. The goal of this paper is to explore if, and how, automated vehicles
(AVs)—vehicles capable of fulfilling human transportation needs by sensing the environment
and navigating without human input—contribute to the overall goal of the TBCCC. The paper
assesses the contribution of AVs limited to two TBCCC sub-goals:
How do AVs contribute to reducing petroleum consumption through fuel economy
improvements, environmentally-friendly driving practices, fewer vehicle miles
traveled, and other fuel-saving practices?
How do AVs contribute to the replacement of petroleum by alternative and renewable
fuels?
To answer these questions, an analysis evaluating the Strengths, Weaknesses,
Opportunities, and Threats (SWOT) of AVs for reducing fuel consumption and promoting
alternative fuels was performed. The SWOT analysis is supported by an extensive literature
review and examines the internal and external factors that are favorable and unfavorable in
order to achieve the sub-goals. For this, it is essential to define the boundaries of the
system and the analysis:
The assessment of strengths and weaknesses focuses on the narrow boundaries of a
single AV. Future work could extend this focus on the potential to grow transit
service/mobility through automated/connected vehicle (CV) technology.
1 The assessment of opportunities and threats examines the broader system of AVs
considering the impact on the overall system traffic, if there is a broad adoption of
alternative fuel vehicles.
Assessing the Strengths and Weaknesses of Single Automated Vehicles
The strengths and weaknesses focus on the narrow boundaries of single AVs, and the
synergies with alternative fuel vehicles are presented. This analysis is supported by initial
reported results from different test vehicles as well as from different model calculations.
The strengths of AVs to reduce fuel consumption are:
Automated vehicles facilitate fuel efficient driving behavior (foresight driving to
reduce stops at intersections, steadier speeds and less frequent stop and go, vehicle
platooning, driving at optimal cruising speed for fuel efficiency, minimizing
unnecessary acceleration and braking, etc. [Schneeberger, 2013]). Predicted fuel
reductions are up to 20 percent (Wadud et al., 2013) or a reduction of 20 to 40
percent (Brown, 2013).
As AVs provide much more safety and significantly reduce the number of accidents
(90%of accidents are caused by human error), they provide the opportunity to
reduce passive safety features in the vehicle (such as crush-collapsing zone)
resulting in much lighter and, hence, more fuel-efficient cars. A potential fuel
reduction of 5 to 25 percent (Wadud et al., 2013) or 45 percent (Brown, 2013) is
estimated.
Automated vehicles with users no longer driving themselves may de-emphasize the
current demand for powerful high performance engines that focus on the human
recreational dimension of driving (Lynch, 2013). Reducing the performance of
engines to match the intended cruising speed may reduce fuel consumption by 5 to
25 percent (Wadud et al., 2013).
The environmental benefits of more efficient driving behavior of AVs will go beyond
the benefits of fuel reduction. A 13 percent reduction of fuel equals significant
emission reductions: CO2, 12 percent; NOx, 37 percent; and HC, 41 percent
(Boriboonsomsin, 2013). In addition, more steady-driving patterns could also result
in a reduction of traffic noise and pollution runoff from streets.
Shifts in propulsion sources to all-electric, hydrogen, compressed, or liquefied
natural gas, or other sources will increase.
The strengths of AVs to promote alternative fuel technologies are:
The increased fuel efficiency resulting from more environmentally friendly driving
patterns of automated vehicles is particularly beneficial to alternative fuel vehicles,
such as electric vehicles, which have a shorter driving range per charge than
conventional fuel vehicles. “Range anxiety,” a barrier to the EV market, could be
eased.
2 AVs can help separate the refueling process from the travel (the car itself can search
for next fuelling station, etc.), hence making alternative fuel vehicles more
convenient to use.
AVs are no longer designed from the “driver” perspective and, hence, may help shift
away from traditional cultural expectations of cars (powerful engines promoting the
joy of driving, etc.) and help to promote alternative fuels (Lynch, 2013).
AVs and alternative fuel vehicles complement each other, as they are both well-
suited for the same type of trips, such as regular commutes in urban agglomerations
(short trips, focus on mobility rather than joy of driving, driven by economic
consumer behavior, etc.).
AVs and alternative fuel vehicles attract the same type of consumers—early adopters
who are willing to test new technologies and appreciate economic and environmental
benefits.
The potential weaknesses of AVs with regards to promoting the reduction of fuel
consumption and adoption of alternative fuel technologies are:
There is uncertainty as to the potential and intention of auto manufacturers to build
lighter and less powerful automated cars that use alternative fuel. The current AVs
tested in the field are still conversions of conventional vehicles.
In examining individual AVs, the analysis illustrates that there are overwhelming strengths
and only limited weaknesses for promoting fuel efficiency and alternative fuel vehicles.
Several synergies between AVs and alternative fuel vehicles are already being explored,
such as the Google car being built on a Toyota Prius (Hybrid) and efforts to upgrade the
electric Nissan Leaf to an AV (two out of five automated vehicles currently tested in the
field) (Knight, 2013; Lynch, 2013). Again, the technology and benefit of AV/CV are
independent of fuel.
Assessing the Opportunities and Threats of AVs on the Overall Traffic Systems
The impact of a broad-scale adoption of alternative fuel AVs on the overall traffic system
and land-use system was explored. As automated vehicles are still at an early testing stage,
it is, by nature, difficult to explore these impacts. These impacts can only be explored using
possible future scenarios.
The opportunities of AVs to reduce fuel consumption in the overall traffic system are:
Platooning (AVs driving in convoys with reduced minimum distance between cars)
will result in reduced aerodynamic drag and, hence, reduced fuel consumption. There
is a particularly high potential to reduce the fuel consumption of truck traffic,
estimated at 10 to 15 percent (Bullis, 2011), 20 percent (Knight 2013), and 5 to 25
percent (Wadud et al., 2013).
Platooning also increases the capacity of streets, avoids costly investment in
roadway expansion, and can contribute to the mitigation of congestion. The fuel
savings from reduced traffic congestion is estimated at up to 5 percent (Wadud et al.
2013).
3 AVs combined with smart parking systems may reduce parking traffic, as they can
directly locate the next parking spot, reducing traffic and idling related to searching
for a spot. A modest reduction of fuel consumption of up to 4 percent is estimated
(Brown, 2013). This also allows changes to existing parking land uses that could
increase productivity for urban centers.
AVs combined with Global Positioning Systems (GPS) can result in more effective
route selection, providing a fuel reduction potential of up to 20 percent (Brown,
2013).
AVs create opportunities to provide new forms of public transport and increase car
occupancy. Innovative forms of public transport in low-density urban areas, such as
automated car-sharing schemes or driverless taxis, could be possible. The potential
for fuel replacement is estimated at 10 to 20 percent (Brown, 2012; Frazzoli, 2013).
AVs can be incorporated into schemes for an environmentally driven operation of the
whole traffic system. Possible solutions include smart signals (cars and signals
coordinated to reduce stops at signals), smart lanes (lanes reserved for cars driving
in efficient platooning patterns), environmentally controlled traffic information
systems (steer traffic flows to reduce environmental impact), integrated corridor
management (intermodal management of traffic corridors, e.g., smart promoting of
switching between cars and public transport) (Schneeberger, 2013; Knoflacher,
2008). Possible fuel reduction savings are in the range of 5 to 10 percent
(Schneeberger, 2013).
The threats of AVs to reduce fuel consumption in the whole traffic system are:
Platooning and increased active car safety may result in increasing average highway
speeds. This increased speed can result in increasing fuel consumption of 5 to 40
percent (Wadud et al., 2013) or 30 percent (Brown, 2013), assuming conventional
fuel sources.
AVs may make access to auto trips possible for groups currently unable to drive
(older adults, children, persons with disabilities, etc.) (Elkind, 2012). As a backdrop
to this positive increase of individual mobility, there may be an overall increase of
miles traveled, resulting in increasing fuel consumption of up to 40 percent (Brown,
2013).
AVs may, in the short term, activate some latent travel demand as more efficient
cars make driving cheaper. This “rebound effect” of increasing technical efficiency
could lead to an increase in miles traveled, hence offsetting the initial perceived
savings (Jevon’s Paradox). The effect is assumed to equal the fuel efficiency savings
of individual cars, resulting in an increase of up to 40 percent of fuel consumption
(Wadud et al., 2013).
In the long-term, AVs may induce some additional traffic demand. The reduced
travel time due to congestion reduction, as well as the opportunity to use the
in-vehicle travel time for productive purposes, may result in behavior changes and
land-use changes. As a result, drivers may be willing to commute longer distances,
4resulting in land use with longer distances between home and work. The resulting
increase of fuel consumption is estimated to be up to 50 percent (Brown, 2013).
The potential for AVs to use in-vehicle time more productively may result in changes
of mode selection. As AVs provide similar benefits to public transport (working or
relaxing during commute), this may reduce the attraction of public transport
(Elkind, 2012).
Conclusions
When focusing on the individual AV, several strengths in promoting fuel reduction and
providing synergies with alternative fuel vehicles have been projected. A reduction of fuel
consumption of 20–50 percent is estimated (Frazzoli, 2013). However, when examining AVs
as part of the entire traffic system, both opportunities to improve fuel efficiency and threats
by the “rebound effects” on system level may be realized, resulting in an increased number
of vehicle miles traveled. Combining the different opportunities and threats of automated
vehicles in different possible future scenarios gives a range of fuel reduction from 20
percent up to an increase of fuel consumption of 50 percent. This assumes the lower end of
reduction and the higher end of consumption induced, but it does not include discussions on
type of fuel being consumed with AV technology (Wadud et al., 2013). At this early stage, it
is difficult to accurately predict the consequences of AVs on the traffic system, with the
exception that safety improvements will be dramatic. To avoid the negative rebound effects
on fuel consumption, it is key to have policies in place that encourage alternative fuel
sources or discourage behaviors that cause additional consumption. The key benefits of AVs
with respect to fuel consumption can be realized only if emphasis is placed on lighter, less
powerful, and fuel-flexible vehicles.
The combination of opportunities and threats at the system level remains highly uncertain
and requires detailed research. AVs have the potential to contribute to the goal of the
TBCCC to reduce fuel consumption, but it is far from certain that this goal actually will be
achieved. In addition, the identification of appropriate accompanying policies is not well
explored at the moment. There is a need to develop policies to ensure that AVs not only
benefit individual drivers, but also exploit opportunities for system optimization—efficient
and integrated corridor management, environmental travel information, etc. (Knoflacher,
2008)—to achieve an overall reduction of fuel consumption and related air pollutants. This
SWOT analysis is just a first step in assessing the environmental fuel consumption impacts
of AVs, and is intended to serve as a prelude to future detailed studies.
5References
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