As discussed above, AVs will have varying effects on the cost of mobility,
vehicle throughput, congestion, and car ownership. All of these
factors influence total VMT. Reduced travel costs from AVs will likely
increase VMT, commonly referred to as the “rebound effect” and
expressed as a percentage increase in VMT that results from a change
in per-mile vehicle costs. NHTSA assumes a rebound rate of 10 percent
for the base case and examines alternate cases of 5, 15, and 20 percent
(NHTSA, 2012a). A 10-percent rebound effect means that if per-mile
vehicle costs fall by 20 percent, VMT demand will rise by 2 percent.
In addition to existing drivers, the emergence of Level 4 AV taxis
and car-sharing services may induce additional VMT demand from
new sources. These include the elderly, the young, those without driver’s
licenses, and those who explicitly or implicitly value the time or multitask
opportunities afforded by driverless taxis at high rates. But if Level 4
driverless taxis are available, easy to use, and cheap, the incentive to own
a vehicle is reduced, and declines in vehicle ownership rates would result.
Table 2.3 outlines these and other potential impacts on total U.S. VMT.
The magnitude and direction of how AVs affect total VMT are
key drivers of change in energy use and emissions from these vehicles.
However, even increases in total VMT can have neutral effects
on energy and environmental impacts as long as vehicle efficiencies
and/or GHG intensities of fuels are reduced. For example, in 2010,
U.S. VMT per capita was 9,608 vehicle miles and VMT per vehicle
in operation was 12,370 miles (Davis, Diegel, and Boundy, 2012). In
a car that gets 31 mpg, one car would consume about 400 gallons of
gasoline traveling 12,370 miles over the course of the year. If driving
habits increased VMT and that vehicle is instead driven 20,000 miles
per year, a 50-mpg car would be required to consume the same amount
of gasoline annually.
Research by : http://www.rand.org/
vehicle throughput, congestion, and car ownership. All of these
factors influence total VMT. Reduced travel costs from AVs will likely
increase VMT, commonly referred to as the “rebound effect” and
expressed as a percentage increase in VMT that results from a change
in per-mile vehicle costs. NHTSA assumes a rebound rate of 10 percent
for the base case and examines alternate cases of 5, 15, and 20 percent
(NHTSA, 2012a). A 10-percent rebound effect means that if per-mile
vehicle costs fall by 20 percent, VMT demand will rise by 2 percent.
In addition to existing drivers, the emergence of Level 4 AV taxis
and car-sharing services may induce additional VMT demand from
new sources. These include the elderly, the young, those without driver’s
licenses, and those who explicitly or implicitly value the time or multitask
opportunities afforded by driverless taxis at high rates. But if Level 4
driverless taxis are available, easy to use, and cheap, the incentive to own
a vehicle is reduced, and declines in vehicle ownership rates would result.
Table 2.3 outlines these and other potential impacts on total U.S. VMT.
The magnitude and direction of how AVs affect total VMT are
key drivers of change in energy use and emissions from these vehicles.
However, even increases in total VMT can have neutral effects
on energy and environmental impacts as long as vehicle efficiencies
and/or GHG intensities of fuels are reduced. For example, in 2010,
U.S. VMT per capita was 9,608 vehicle miles and VMT per vehicle
in operation was 12,370 miles (Davis, Diegel, and Boundy, 2012). In
a car that gets 31 mpg, one car would consume about 400 gallons of
gasoline traveling 12,370 miles over the course of the year. If driving
habits increased VMT and that vehicle is instead driven 20,000 miles
per year, a 50-mpg car would be required to consume the same amount
of gasoline annually.
Research by : http://www.rand.org/
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