Double stack freight rail transportation is up to five times more fuel efficient than truck transportation, according to a new report by the Federal Railroad Administration.

The "Comparative Evaluation of Rail and Truck Fuel Efficiency on Competitive Corridors" report indicated that rail fuel efficiency has improved by about 20 percent, or 1.1 percent per year, between 1990 and 2006.

The improvement in the fuel efficiency of rail is attributed to changes in traffic mix, technological improvements, and changes in operating practices that lowered fuel consumption, the report said.

"While all types of transportation are vital to the distribution of goods across the country, this study shows that utilizing America's freight rail system can lead to significant fuel savings," said Joseph Szabo, FRA administrator. "The environmental benefits of these positive changes over the last two decades are enormous."

Another contributor to this fuel efficiency savings is the increasing popularity of double stack trains, which have become more predominant in the past two decades because of their fast and reliable transit times, the report said.

Double stack trains also tend to be more fuel efficient. The double stack rail-to-truck Fuel Efficiency Ratio ranged from 2.7 to 5.5 in this study, compared to a ratio of 2.5 to 3.4 in the 1991 study.

To view the entire FRA report, click here.