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

Transportation’s Role in Reducing U.S. Greenhouse Gas Emissions: Volume 2
Cost-Effectiveness
While increasing truck size and weight limits would involve only modest administrative
costs, heavy trucks cause more damage to the nation’s infrastructure than do lighter
vehicles and would therefore more significantly increase infrastructure maintenance costs.
However, vehicle owners and shippers would benefit significantly from reduced vehicle
operating costs, and therefore, fees could be charged to recover the added infrastructure
costs. The Moving Cooler study estimated the cost-effectiveness of increased size and
weight permits to be about -$1,200 per tonne CO2e reduced—reflecting a net cost savings
(Cambridge Systematics, 2009).
Estimates of total pavement costs and the State cost responsibility from the Federal
pavement cost responsibility from the Federal Highway Cost Allocation Study (FHWA,
2000) suggest that it would cost $399 million ($0.1875 per new VMT) to cover the
maintenance costs from allowing dray trucks to carry heavier containers and $432 million
($0.481 per new VMT) to cover the costs of allowing heavier natural resource vehicles.
Heavier and longer trucks mean fewer trucks and lower vehicle operating costs, due to
both fuel and labor savings. Allowing heavier natural resource vehicles is estimated to
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Safety Impacts of Heavy and Long Combination Vehicles
While heavy and long-combination trucks have generally been opposed due to safety concerns, the literature
on this topic is inconclusive. A literature review by the Canada Safety Council (2003) found mixed evidence
on the safety impacts of long combination vehicles (LCV). Some studies suggest that LCVs tend to crash more
than single trailer trucks, while others suggest that they tend to crash less often. The picture is muddied by
the inability of researchers to compare the two modes with “all else being equal.” That is, the truckers who
drive LCVs are generally more highly skilled than the average tractor trailer driver, they are restricted to the
safest roads, and can only operate in the safest weather conditions. The risk exposure is different for LCV
operations than it is for normal truck operations. Analysts have arrived at differing conclusions depending
upon how they account for these risk factors.
Furthermore, crash severity is a concern as well as crash frequency. A 1999 FHWA report suggests that
LCV crashes tend to be marginally more severe than normal trucks, with a slightly higher injury rate (31.28
per million VMT for multiples compared to 28.01 for singles) but no significant difference in fatality rates
(2.44 per million VMT for multiples compared to 2.43 for single trailers).
The same literature review (Canada Safety Council, 2003) found no research about the safety record of
heavy vehicles of normal size. They will likely follow a similar pattern of crash rates to LCVs due to
decreased maneuverability.
To the extent that LCVs and heavy trucks reduce overall truck VMT, they have the potential to reduce crashes
even if crash rates (on a per-mile basis) are similar. A study by the Transportation Research Board (TRB 2002)
found that differences in crash involvement rates among different truck types are smaller than the differences
in vehicle capacity and the vehicles they would replace, so involvement rates per unit of truck services should
decline. This finding suggests that increased use of heavy trucks and LCVs should have a net safety benefit,
assuming that regulations are implemented in such a way as to reduce overall truck VMT (as required to
achieve greenhouse gas reductions). If LCV and heavy truck use were expanded to more urbanized areas
with higher traffic volumes and congestion levels, however, it is possible that the overall safety impacts could
be different.