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Freight Trains
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Trains are the most fuel-efficient method of transporting goods across land. Trains are two to four times more efficient at transporting freight than conventional trucks, depending on the cargo, and a single freight train can carry the equivalent of 280 truckloads .The rail shipping company CSX claims it can transport one ton of cargo 500 miles (805 kilometers) on a single gallon of fuel. Modern trains have increased their energy efficiency 106 percent since 1980 and recent technological breakthroughs -- in locomotive design and computerized train control -- will raise fuel efficiency by another 25 percent or more in the next decade.

Freight rail currently accounts for 2.1 percent of the total greenhouse gas emissions produced by the entire U.S. transportation sector. According to the Environmental Protection Agency, the biggest polluter by far is passenger vehicles at 65.8 percent, but trucks contribute a significant 20.4 percent. The Association of American Railroads estimates that if 10 percent of truck cargo was moved to the rails, it would lower greenhouse emissions by 12 million tons annually -- or the equivalent of taking 2 million cars off the road.

<b>The Newer, Greener Trains</b>

Next-generation "Gen Set" locomotives bring a new level of fuel efficiency to freight trains. Instead of running on one large diesel engine, these new locomotives use three smaller engines. If low horsepower is needed, only one engine engages. If the terrain or cargo requires more horsepower, then more engines engage automatically. By tailoring the horsepower to track or load conditions, these locomotives cut down on wasted fuel by as much as 25 percent, according to Norfolk Southern.

Even more efficient hybrid electric-diesel locomotives are currently used by smaller "switching" locomotives, but the technology is still being developed to power larger trains.

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