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Low-Hanging Fruit for Big-Rig Fuel Efficiency: The Trailers the EPA Didn't Regulate

As I reported, environmentalists, truckers and government officials held hands at the announcement of combined fuel economy and greenhouse gas regulations for big rigs on Monday. Everyone agreed the new regs would save money for long-distance haulers, while also providing important environmental benefits. But the exhaustive, collaborative process left out one key tractor-trailer component -- the trailer. And there's some real savings available there.

The regulations don't require any improvements to the big, interchangeable boxes (containers on wheels) that move most of our freight in the U.S. But Randy Mullett, vice president of government affairs at large national hauler Con-way (CNW), which operates 43,000 tractors and trailers, points out that by improving the trailers the combo rigs could make fuel economy improvements of 15 percent or more. And when semis are four percent of the vehicles on the road but use 20 percent of the fuel, that's a big savings.

"This is an old-timey business but there's a lot of cool stuff happening," Mullett said. Here are some key "off the shelf" components for improving truck trailers:

  • Improve aerodynamics. Box-like long-haul trucks are about 45 percent less aerodynamic than typical passenger cars, so there's a lot that can be improved there. From SmartTruck, there's a bolt-on trailer under-tray system made of neoprene that can be retrofitted (or added to new trucks) to act as an alternative to trailer side skirts to improve aerodynamics dramatically. In testing, the under-tray improved air flow enough to add an 11.5 percent fuel economy improvement. The system is comparable in price to the $1,000 to $3,000 side skirts it replaces.
  • Make it lighter. Trailers can replace steel with aluminum, including in the framing, to yield big weight savings. Other smart tweaks would also reduce weight without losing trailer strength.
  • Reduce friction. Low-rolling-resistance tires on trailers also offer an important savings. The National Academy of Sciences' "Technologies and Approaches to Reducing the Fuel Consumption of Medium- and Heavy-Duty Vehicles" report, issued last March, estimated that improving the rolling resistance of trailers can improve energy loss 12 percent in urban areas, and 13 to 15 percent on interstates.
  • Slow down. Speed limits would also offer fuel savings, because trucks lose efficiency at higher velocity. The American Trucking Associations advocate a 65-mph national speed limit for trucks. Con-way puts speed governors on its trucks, as many operators do, and recently dialed down long-haul trucks from 70 to 65, and shorter-haul vehicles from 65 to 62. Tampering with the speed governor is a firing offense.
  • Road trains. Other fruit that can be plucked, some of it low-hanging, includes modifying the laws to allow truckers to install aerodynamic wings on the back of their trailers without also having to reduce cargo size, and allowing more tandem trucks. The latter is controversial, because extended trucks are considered dangerous, but Mullett points to the huge "road trains," with up to four full-length trailers, running in the north-south Australian outback routes. "We're limited to 80,000 pounds in the U.S.," he said, "and that makes us an outlier on reliable truck weights. In most of the world, much larger trucks are on the road." They call them road trains for a reason, because there's much greater fuel efficiency in stringing trailers behind a single cab. Nobody's suggesting letting road trains rumble through downtowns, but they might work on relatively isolated routes.
Truck trailers last much longer than the cabs do, so it's a very good thing to make them more efficient. EPA and NHTSA wanted to get a ruling out, but phase II should definitely take a close look at regulating trailers.


Graphic: SmartWay