Photograph by John Eastcott and Yva Momatiuk, National Geographic
Published September 23, 2011
Just over 33 years ago, 33 truckers competed for three days in a fuel economy contest dubbed the "Double Nickel Challenge." Named after radio slang for the 55 miles per hour (89 kilometer-per-hour) speed limit then in force in the United States, the goal was simple: to test the claim, common among truckers at the time, that big rigs got better mileage at higher speeds.
Long-haul truckers from all over the United States gathered in East Liberty, Ohio, to watch as drivers navigated laps around a track—first at 55 mph, and then at any speed of their choosing. With a few exceptions, they burned less fuel in the first, speed-limited, trial.
More than three decades later, the double-nickel U.S. speed limit—enacted in the wake of the 1973 Arab oil embargo—has faded into history on most highways. But so has credibility for the claim that higher truck speeds beget better fuel economy.
In fact, road-speed "governors," electronic engine controls that limit driver speed, are standard equipment on modern 18-wheelers. In Europe all trucks have their road-speed governors set by the factory to a specified value determined by law. In the United States, it's up to the vehicle owner to decide the setting, but most large fleet operators electronically limit their drivers to 60 to 63 miles an hour (97 to 101 kilometers per hour), with some flexibility to accelerate when needed. Safety is one consideration, but the other aim is to save on the cost of fuel.
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Yet both the trucking industry and policy makers are convinced that more can be done to curb the growing amount of fuel that is being burned by big rigs hauling goods from one place to another. The U.S. government, in fact, this summer announced its very first fuel economy standards for heavy-duty vehicles, seeking to require that big tractor-trailers get 20 percent better mileage by 2018. Europe also is working on a framework for limiting trucking fuel consumption and carbon emissions. And Japan, where trucks are estimated to be responsible for 25 percent of automotive greenhouse gas emissions, set standards to improve trucking fuel performance in 2006.
Changes in truck aerodynamics, reduction of mass, and improved rolling resistance all are strategies that could yield significant improvements in fuel economy, according to a U.S. National Academy of Sciences (NAS) report issued last year. But on par with all of those, the NAS put "intelligent vehicle" systems-many available today-which can reduce the fuel burned by trucks by encouraging changes in driver behavior that have long been known to save fuel.
The Fuel-Saving Power of Data
Curbing driver speed is perhaps the most widely recognized behavioral change that can save fuel, with the low 60 to 65 mph (about 100 kilometer-per hour) range the "sweet spot" for many of the 18-wheelers on today's highways, said Glen Kedzie, vice president of environmental affairs for the American Trucking Associations, a trade group headquartered in Arlington, Virginia.
On average, a truck traveling at 65 mph instead of 75 mph will experience up to 27 percent improvement in fuel consumption. "As a rule of thumb, for every one mile per hour increase in speed, there is a corresponding 0.14 mpg penalty in fuel consumption," said Kedzie.
Operating at even lower speeds (around the old double-nickel limit, for example) would further reduce aerodynamic drag and decrease fuel consumption, he said, but safety risks increase if trucks travel much slower than cars. And the problem voiced by truckers during the days of the Double Nickel Challenge-that of slower speeds translating to less income-remains today.
(Related: "A Fuel That Doesn't Go to Waste")
In the United States, Australia, Canada, and European countries, for example, "hours of service" regulations force truckers to rest after a certain number of hours on the road. "Some trucks traveling at 55 may not be able to get their loads to their destinations on time," Kedzie explained.
Fortunately, the tool kit for eking out extra miles per gallon has expanded far beyond driving speed. In an era of evermore intelligent and connected vehicles, trucking technology for better fuel economy now includes wireless sensors, GPS chips, algorithms, and sophisticated real-time data analysis. "The rate of change is getting faster and faster," Kedzie said.
Fleet operators can collect highly detailed information about a given driver and vehicle, for example. "They almost have a real-time printout of a specific driver," Kedzie said. He ran off a list of data points that a growing number of U.S. fleets are monitoring: "Where they stopped, how long they rested, how often they braked and how often they hard-braked, the temperature of the engine."
It might sound like Big Brother has moved into the trucking industry. But analyzing this data and training drivers accordingly can translate to real savings. As Michael Roeth, executive director of the North American Council for Freight Efficiency, put it, "Between the worst driver and the best driver," the difference in fuel economy can be up to 25 percent.
Others cite more modest gains from technology designed to encourage more fuel-efficient driving behavior. For example, GreenRoad, based in Redwood City, California, says drivers using its real-time feedback system consistently cut fuel and maintenance costs by 10 percent. The big oil and gas company Shell* says its FuelSave Challenge Partner system for commercial trucks also can improve fuel economy by 10 percent. The Shell system collects information on 13 separate driver behaviors, such as harsh braking and excessive engine revving, and on a weekly or monthly basis, reports emissions, fuel, and efficiency data to fleet managers.
(Related: "Fuel-Saving Driving Tips")
According to Roeth, tractor-trailers in the United States currently average just 6 mpg (2.55 kilometers per liter). But some fleets can achieve up to 8.5 mpg (3.61 kilometers per liter), with the most efficient trucks reaching 10.5 mpg (4.46 kilometers per liter). "If we could bring the average up to the best real-world experience today," he said, "incredible cost would come out of freight." At current diesel fuel prices, he said, each one percent improvement in fuel economy saves about $900 per truck annually.
A Trucking Transition
The tipping point doesn't seem far off. "The truck fleet is as old as it's ever been," said Roeth. That's because, in hard economic times, fleet operators are "keeping trucks longer than they ever have." But new purchases can be postponed for only so long, and an influx of new trucks will hit U.S. highways within the next few years, according to Roeth.
It's an opportune time for the recently finalized fuel economy standards in the United States, where liquid fuel consumption by medium- and heavy-duty vehicles represents 26 percent of all transportation fuels burned. Trucking fuel consumption has increased more rapidly-in both absolute and percentage terms-than consumption by passenger vehicles.
(Related: "New Fuel Economy Labels for U.S. Vehicles")
Analysts at the firm ACT Research predict that North American production of Class 8 trucks (the heaviest trucks on the road, including big rigs) in 2012 and 2013 will be about 628,000, including an estimated 45,000 trucks to be exported to countries including Australia, South Africa, and Russia, ACT president Kenny Vieth said in an interview.
"That is nearly the total of all trucks built in the four years of 2007 through 2010. Twice as many!" Roeth wrote in an email. "It is crucial these trucks are bought with the most features for fuel economy."
It's not just a North American trend. ACT researchers are seeing "a really strong jump in the EU," Vieth said. And he added, "Demand is off the Richter scale in China," with heavy-duty truck purchases skyrocketing to more than 1.1 million in 2010, from just about 200,000 in 2001. "It's a deeply cyclical industry, either feast or famine," he said.
(Related: "Trucks Could Be Next Electric Power Frontier")
A major reason such strong growth is expected in the next couple years compared to the last few, is "the market was profoundly weak." Back in 2006, for example, North America produced more than 375,000 heavy trucks, about 40,000 more than ACT predicts for 2013.
Still, the fact is truck purchases have been down, and hundreds of thousands of new trucks will in all likelihood begin moving the world's freight within the next two years. Roeth noted that it's the fuel efficiency per ton of freight that must improve: "We like ton-miles per gallon," he explained. "Just because pickup trucks can go 20 miles per gallon (8.5 kilometers per liter), we wouldn't want 60 pickups hauling what one tractor-trailer can [haul]."
The drive to use technology for improved big rig fuel economy reflects several fundamental changes in the business of moving freight by truck, from new emission standards to rising fuel prices. At the same time, trucks are getting heavier. "But the overall weight limit hasn't changed," Roeth said. So trucks need to be able to haul more weight using smaller engines and fuel tanks.
"In 20 years, we've had five versions of pollutant emission standards," said Roeth. Scrubbing systems and other equipment required under those regulations tend to add weight. Trucking companies also want "sleepers" to provide more creature comforts in order to help retain the best drivers-not a small consideration as companies face a shortage of young drivers coming up to replace those now nearing retirement age.
"Our customers are looking for every opportunity to save fuel," said Peter Adams, program manager for Smart Transport at Shell Global. While acknowledging that Shell hopes its subscription-based FuelSave system will increase loyalty among commercial truckers, Adams explained the move to sell fuel-saving technology: "If we help our customers manage their fuel effectively, they remain profitable, in business, and keep buying fuel."
In the Netherlands, for example, the Emons Group has piloted the Shell FuelSave Partner on 17 trucks in its recycling division. The company's 450 trucks, which haul chemicals, glass, and other cargo, consume 15 million liters (nearly 4 million gallons) per year. Fuel alone accounts for about one quarter of Emons' costs. By 2012, Emons aims to slash fuel use by 20 percent. The 17 trucks using the Shell system for six months dropped fuel consumption by an average of 5.3 percent, with some individual drivers achieving 10 percent savings.
"The sky's the limit as to what information you can get out of technology," Kedzie said. It's becoming possible, for example, for a truck to be programmed to shift at just the right time for maximum fuel efficiency and minimum wear and tear. Braking can be automated, with the proper distance calculated based on road conditions, weather, and load weight. Other systems, using retinal observation, are being marketed to detect signs of driver fatigue. "Trucks are heading down the path of becoming more intelligent," he added, "which will result in the industry becoming safer, more fuel efficient, and more productive."
* This story is produced as part of National Geographic’s Great Energy Challenge initiative, sponsored by Shell. National Geographic maintains autonomy over content.
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