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

Transportation's Role in Reducing U.S. Greenhouse Gas Emissions: Volume 1
3-14
While their GHG benefits may be modest, highway traffic management and
traveler information strategies have significant co-benefits, especially in the form
of time-savings to travelers, as well as the economic benefit of cost-savings for
shippers. Traffic management strategies such as signal coordination and
incident management are proven, have relatively modest costs, and could be
more broadly deployed within the next 5 to 10 years—yielding early GHG
reductions that may be significant at a local scale.
Highway bottleneck relief strategies involve increasing capacity at
“bottlenecks” (specific points on the transportation network where demand
exceeds capacity), through such measures as added lanes, interchange
improvements, and intersection reconfigurations. Outside analysis from the
Moving Cooler study shows modest GHG reductions from bottleneck relief
strategies in 2030, but modest increases in GHG emissions by 2050, because of
induced demand. 80
A Federal policy to reduce speed limits (for example, from 70 to 60 mph or from
65 to 55 mph) on national highways would generate substantial immediate
benefits, reducing total transportation GHG emissions by 1.1 to 1.8 percent; in
addition to having significant safety benefits. However, achieving these benefits
would require strong enforcement, and by reducing travel speeds this strategy
would increase travel times, and could increase costs to shippers. Stronger
Federal funding incentives and disincentives, coupled with Federal oversight,
would be required to achieve more effective enforcement if this strategy is
pursued. This strategy is quite cost-effective, with enforcement costs of about
$10/tonne GHG reduced. 81
much as 0.6 percent in 2030 (see Vol. 2, Sec. 4.2.1). The Moving Cooler estimates also
showed net GHG reductions in 2050.
80 The Moving Cooler study analyzed the impact of bottleneck relief construction projects
at the top 200 bottlenecks in the United States. It found that bottleneck relief strategies
would achieve a net reduction in GHGs of 4 mmt CO2e under maximum deployment
in 2030 and a net increase in GHGs of 10 mmt CO2e under maximum deployment in
2050. That corresponds to a 0.3% decrease in US on road GHGs in 2030 and a 0.7%
increase in US on road GHGs in 2050. These estimates do not include construction
emissions (see Vol. 2, Sec. 4.2.3). The bottleneck relief estimates also assume that the
projects would be fully financed by increased fuel taxes, which somewhat mitigates the
induced travel demand resulting from congestion relief.
81 Vol. 2 Sec. 4.2.4.