Environmental effects

Trucks contribute to air, noise, and water pollution in a similar fashion to automobiles. In the case of air pollution emissions, trucks may actually emit lower emissions than autos on a per pound of vehicle mass basis, although the absolute level on a vehicle mile traveled basis is higher and diesel soot is especially problematic for health.[2] With respect to noise pollution trucks emit considerably higher sound levels at all speeds compared to typical automobiles; this contrast is particularly strong in the case of heavy duty trucks.[3]

Concerns have been raised about the effect of trucking on the environment, particularly as part of the debate on global warming. In the period from 1990 to 2003, carbon dioxide emissions from transportation sources increased by 20%, despite improvements in vehicle fuel efficiency.[4]

In 2005, Transportation accounted for 27% of U.S. greenhouse gas emission, increasing faster than any other sector.[5]

Between 1985 and 2004, in the U.S., energy consumption in freight transportation grew nearly 53%, while the number of ton-miles carried increased only 43%.[6] "Modal shifts account for a nearly a 23% increase in energy consumption over this period. Much of this shift is due to a greater fraction of freight ton-miles being carried via truck and air, as compared to water, rail, and pipelines."
According to a 1995 U.S. Government estimate, the energy cost of carrying a ton of freight a distance of one mile averages 514 Btu for water, 337 Btu for rail, 3,100 for trucks and nearly 20,000 for air transport.[7] and many environment organizations favor laws and incentives to encourage the switch from road to rail, especially in Europe.