Two Chattanooga trucking companies have won national environmental awards for saving fuel and reducing greenhouse gases.

U.S. Xpress and Covenant Transport saved 91.1 million gallons of fuel and prevented the release of more than 1 million tons of CO2 — carbon dioxide, an ingredient of smog.

For their work, they were among 37 firms nationwide to receive “SmartWay Excellence Awards” from the U.S. Environmental Protection Agency.

“EPA’s SmartWay partnership helps freight companies go the extra mile by saving fuel and money while cutting air pollution,” said Gina McCarthy, assistant administrator for EPA’s Office of Air and Radiation.

“We believe that conservation is good business,” said U.S. Xpress Co-Chairman Max Fuller in a news release. He said the company's focus on research is one of the key elements to its approach with green initiatives.

Covenant Transport President Joey Hogan said the company’s workers and drivers deserve the credit for winning the award for a second straight year.

“We believe it is incumbent on our company to lead by example the charge in our industry to become better environmental stewards,” he said.

U.S. Xpress Enterprises, Inc./Xpress Global, a large, privately held truckload carrier with about 6,000 late-model tractors and more than 14,000 trailers, took a prototype trailer with improved aerodynamics developed with the National Center for Computational Engineering at the University of Tennessee at Chattanooga.

Then U.S. Xpress took the model to its trailer vendors and worked to develop a test model.

All new 2009 tractors brought into U.S Xpress fleet during 2008 had engines that could pass California air standards, which are the strictest in the nation.

They also were equipped with wide-based tires that include a tire pressure monitoring system, because low tire pressure lessens fuel economy. The company employs advanced computerized freight and global positioning systems that in 2008 helped it reduce empty miles by 1.5 percent.

Covenant, a smaller truckload for-hire and contract trucking company, made the difference by equipping its fleet with aerodynamic packages, idle-reduction technologies, fuel efficient tires and low-friction engine and drive train lubricants.

As its fleet turned over, Covenant also invested in SmartWay-certified tractors and trailers, and began using team drivers, Pre-Pass and truck stop electrification.

at a glance

U.S. Xpress Enterprises Inc.

* 63.1 million gallons of fuel saved

* 701,289 tons of carbon dioxide not released

Covenant Transport Inc.

* 28 million gallons of fuel saved

* 21,900 tons of particulate matter not released

* 307,368 tons of carbon dioxide not released

Source: U.S. Environmental Protection Agency

Southeast winners

Home Depot, Atlanta

Georgia-Pacific, Atlanta

UPS Diesel, Atlanta

Lowe’s Company Inc., Mooresville, N.C.

Kimberly Clark Corp., Knoxville

Covenant Transport Inc., Chattanooga

US Xpress Enterprises Inc./Xpress Global, Chattanooga

Source: U.S. Environmental Protection Agency