Transportation's Role in Reducing U.S. Greenhouse Gas Emissions ...

Transportation’s Role in Reducing U.S. Greenhouse Gas Emissions: Volume 2
Summary of Impacts
Pricing strategies are among the travel activity strategies evaluated in this report with the
greatest potential to reduce GHG emissions. Economists argue that pricing strategies can
internalize the costs of the externalities associated with travel, 2 discourage low-value trips,
and encourage more efficient use of the transportation network. Comprehensive pricing
strategies that affect all travel—including VMT fees and pay-as-you-drive insurance—
could potentially each reduce GHG emissions in the short term 3 by up to 3 percent of all
transportation emissions at typical levels of implementation, or about 75 million metric
tons carbon dioxide-equivalent (mmt CO2e) emissions. If applied together, impacts would
be greater. Strategies focused on specific markets, such as intercity tolls or cordon pricing,
will have much smaller benefits consistent with the size of the market affected, and may
also have some offsetting negative impacts by shifting vehicle-travel to unpriced locations
rather than reducing it outright. Congestion pricing—in which higher prices are charged
for traveling in periods of high demand—will not only reduce VMT, but also result in
more efficient traffic operations. Benefits from comprehensive congestion pricing on all
roadways could be as high as 1.4 percent of transportation GHG emissions or 35 mmt
CO2e, but this figure is subject to substantial uncertainty.
Despite its effectiveness, increasing the price of travel has so far proven unpopular with
the general public. In general, in order for pricing to yield net benefits to the traveling
public and not produce unacceptable equity impacts, a large fraction of the revenues must
be reinvested in transportation services that benefit travelers (such as transit) and/or
returned to the public (for example, through tax rebates). Potential Federal policies to
encourage more widespread pricing include: implementing a national VMT fee system to
replace or supplement the gas tax; easing or eliminating restrictions on congestion pricing
programs and tolling on Interstate highways; providing funding for congestion pricing
programs or making Federal funding contingent upon adoption of pricing strategies by
States or metropolitan agencies; and establishing requirements to ensure that pricing
revenue is used in a way that addresses equity concerns.
Investments in transit also have the potential to generate modest to moderate reductions
in GHG emissions. Expansion of and improvements to urban transit have the potential to
reduce transportation GHG by 0.2 to 0.9 percent by 2030, or 5 to 19 mmt CO2e. 4 Benefits
2 Externalities can be defined as environmental, congestion, and other impacts that the traveler
imposes on others but does not directly incur, and therefore does not generally factor into his or
her decision-making.
3 In this report, “short-term” refers to benefits realized within five years or less (2015); “mid-term”
refers to benefits realized in about 20 years (2030); and “long-term” refers to benefits realized in 30
to 40 years (2050).
4 Some of the benefit estimates for a number of travel activity strategies, including transit,
nonmotorized improvements, land use, and commuter strategies, incorporate “induced demand”
effects. As some travelers shift to other modes or reduce their travel, roadway congestion will be
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