Old Steam Trucks

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.
In 2005, transportation accounted for 27% of U.S. greenhouse gas emission, increasing faster than any other sector.
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%.
According to a 1995 U.S. government estimate, the energy cost of carrying one ton of freight a distance of one kilometer averages 337 kJ for water, 221 kJ for rail, 2,000 kJ for trucks, and nearly 13,000 kJ for air transport. Many environmental organizations favor laws and incentives to encourage the switch from road to rail, especially in Europe.