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

Transportation’s Role in Reducing U.S. Greenhouse Gas Emissions: Volume 2
Reduced speed limits can be implemented very quickly, limited only by the time required
for re-signage and public notification, as well as the implementation time required to
upgrade enforcement levels in order to reach full benefits.
Cost-Effectiveness
The immediate costs associated with implementing speed limit reductions are relatively
small, including new signage and public outreach and education effort. Ongoing
enforcement costs will be more significant. Public outreach program costs can vary
substantially depending upon media selection, frequency, and duration of messaging, and
other factors. The IEA (2005) study estimated a $3 million cost for a basic national public
information campaign, assuming no advertising cost for public service announcements;
paid advertising could increase this cost substantially. Incremental enforcement efforts or
citation costs above those already in place were estimated in the IEA report at $200,000 per
additional officer and $26,000 per speed camera. Estimated national costs would be
approximately $600 million annually for personnel, or $800 million initially for speed
camera deployment (not including operations and maintenance/replacement costs, which
were not estimated).
Considering annual enforcement personnel costs alone produces a cost-effectiveness
estimate of about $11 per tonne CO2e reduced, using IEA’s benefit estimates. However,
the IEA study concluded that these enforcement costs were effectively canceled out by
fuel-cost savings. Both fuel-cost savings and enforcement costs would accrue to drivers,
assuming that enforcement costs were fully recovered through fines. The study did not
consider increased travel time costs. Cost and GHG reduction data from the Moving
Cooler study suggest a cost-effectiveness of -$320 per tonne, considering vehicle operating
cost savings but not travel time costs.
State analyses for climate action plans have produced varying estimates of costeffectiveness,
from $-200 to $55 per tonne of CO2 reduced. These proposals included both
increased enforcement and lowered limits, and several applied only to heavy-duty trucks.
Some also included vehicle operating cost savings.
Cobenefits
Speed limit reductions would result in fuel savings and other vehicle operating-cost
savings, but also increased travel time costs. Tradeoffs between fuel-cost savings and
travel time costs can especially factor into freight transporters’ practices; for example, in
March 2008 one major trucking firm announced that it was limiting speeds to 62 mph in
order to reduce fuel consumption (Marketwire, 2008), suggesting that the travel time
savings above that speed were of less value than the increased fuel costs.
Speed limit reductions also would have safety benefits. A National Academy of Sciences
analysis estimated that 4,000 traffic fatalities were averted per year as a result of the
previous national speed limit (TRB, 1984), which translates into $24.4 billion using the U.S.
EPA, Science Advisory Board $6.1 million “value for a statistical life.”
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