Study Finds Green Benefits from Using Larger Trucks

This story appears in the May 11 print edition of Transport Topics.

NASHVILLE, Tenn. — Larger, heavier trucks would not be just an economic boost, but also a means of cutting annual petroleum usage by billions of gallons and sharply reducing greenhouse gases, a university researcher told a gathering of shippers here.

The analysis estimated diesel fuel consumption would drop by as much as 3 billion gallons and greenhouse gas emissions would fall by 32.6 million tons a year if the United States were to increase the gross vehicle weight ceiling for tractor-trailers to 97,000 pounds and allow twin 53-foot trailer combinations on all interstate highways.

“That is an enormous benefit by anyone’s calculation,” said John Woodrooffe, head of transportation safety analysis at the Transportation Research Institute of the University of Michigan in Ann Arbor.

Tractor-trailer rigs consume approximately 30 billion gallons of fuel a year, according to industry estimates.

UMTRI and Woodrooffe were commissioned to study the activity of seven private truck fleets by the National Private Truck Council. The results were released here on May 4 at the group’s annual conference.

Gary Petty, NPTC president, said he hopes the study will provide an “important new dimension” to the political debate over whether to increase federal size-and-weight limits on trucks. Highlighting environmental and safety benefits could join the usual discussion on benefits to business from lower transportation costs.

“This makes a more compelling argument than was the case before,” Petty said. “We feel now there is a window of opportunity for this type of change.”

NPTC and other industry groups, including American Trucking Associations, are expected to make a push to expand use of larger commercial trucks as part of the federal highway funding debate this year.

The Coalition for Transportation Productivity, a group formed in 2008 by companies and trade associations representing shippers of food and agricultural products, called on Congress to act.

“We are asking Congress to address this issue now before America’s highways become even more congested,” John Runyan, senior manager of federal government relations for International Paper and co-chairman of the coalition, said in a statement May 4.

Runyan said allowing six-axle vehicles to carry up to 97,000 pounds on federal highways will save lives, and contribute to economic growth while reducing fuel usage and lowering carbon emissions. The typical heavy-duty rig today carries 80,000 pounds over five axles.

Coalition members said they are willing to pay a user fee on trailers equipped with the additional axle to provide money for bridge repairs.

Woodrooffe said tractor-trailers account for 59% of total fuel consumption by commercial vehicles, so it makes sense to concentrate on making those vehicles more fuel efficient. He calculated that im-proving the performance of the engine and reducing aerodynamic drag by 10% would yield an im-provement of 0.67 miles per gallon. Allowing the same tractors to carry more cargo, however, would result in an estimated 0.77 miles per gallon gain, with no additional technology needed.

“Nothing would be limiting it,” Woodrooffe said, “except politics.”

Woodrooffe said if current vehicle limitations remain in place, more trucks will be needed to meet rising demand for long-term freight hauling.

Not doing anything, he said, “means wasting valuable national resources and business capital. We would be underutilizing infrastructure and not realizing our full potential as a nation.”

Next month, UMTRI will host a conference in Ann Arbor to look at how regulations in other countries compare with those of the United States. Woodrooffe is considered an expert in truck-involved crashes and has worked as a consultant in Australia to develop size-and-weight standards and safety policies for trucks.

In 2001, according to coalition officials, the United Kingdom raised the gross vehicle weight limit for six-axle trucks to 97,000 pounds. Since then, the total tonnage shipped has increased, while the vehicle-miles traveled to deliver those goods have leveled off.

“Most importantly,” Runyan said, “fatal truck-related accident rates have declined. This outcome is exactly what we would like to replicate in the U.S. — safer, more efficient truck transportation.”