With the number of big working trucks more than doubling in the last decade, trucks account for more than half of all U.S. fuel consumption, according to a new study.

The U.S. Commercial Fleet Market Forecast, 2004-2008, by the market research firm Havill & Company Inc., said the number of trucks on the road has grown more than twice as fast as the overall vehicle population in the past 15 years.

“The concern about rising fuel prices permeates this study,” Justin Zohn, Havill senior consultant, told Today’s Trucking. “This has heightened the need to find cost savings in virtually every aspect of fleet operations.”

The study is still being evaluated and will be released in August 2005.