Aerodynamic Devices Aid Trailer Airflow, Enhance Fuel Economy, Carrier Execs Say

By Mindy Long, Special to Transport Topics

This story appears in the June 2 print edition of Transport Topics.

Carriers and aftermarket manufacturers are working to improve fuel economy by bolstering the airflow around every aspect of a trailer with a variety of devices, including side skirts, trailer tails, wheel covers, air tabs and mudflaps.

While some of the devices provide only small fuel savings, when added up, they can cut costs substantially, makers said.

According to the National Research Council, using trailer skirts and tails, aerodynamic details on tractors and closing the gap between the trailer and the tractor will cut fuel costs by 15%. Add in the mudflaps, which a manufacturer and fleets said could save about 1%; wheel covers, which a manufacturer said could save 2% and you’ve cut fuel costs possibly by more than 18%.

Carriers agreed that it is important to conduct their own tests on the devices in their typical operating conditions.

“What works for one fleet doesn’t necessarily work for another fleet. Even within our own fleet, we might have something that works in one area but not in another,” said Bill Bliem, senior vice president of fleet services for NFI Industries, a transportation and logistics company based in Cherry Hill, New Jersey. NFI ranks No. 25 on the Transport Topics Top 100 list of the largest U.S. and Canadian for-hire carriers.

NFI has about 7,500 trailers but uses side skirts only in certain environments, such as the Midwest, where there are strong crosswinds.

“We do not see a benefit in them running in the Northeast, where our guys are going up and down the turnpikes doing 55 miles per hour. Where we are running them [is] in Kansas, Iowa, across the Plains,” Bliem said, adding that NFI uses skirts from Transtex Composite.

Richard Senatro, president of side skirt manufacturer Strehl, said his skirts can result in a 4% increase in fuel economy.

They sell for around $1,000 per trailer.

“People accept that the savings are real, and the damage that our customers are seeing is less than they feared. Our replacement parts rate is less than half of 1%,” he said.

More than half of the trailers that Wabash National Corp. produced in 2013 had a side skirt installed, said Jamie Scarcelli, vice president at Wabash Composites, a unit of Wabash National.

Craig Bennett, senior vice president of sales and marketing at Utility Trailer Manufacturing Co., said about 33% of all refrigerated and dry van trailers it makes have side skirts.

“Those things do work. People will save 2-4% on their fuel bill,” he said.

For less-than-truckload carriers with a lot of stops and urban deliveries, getting the value out of aerodynamic devices can be more difficult.

LTL carrier A. Duie Pyle Cos., No. 85 on the for-hire TT100, has equipped a small portion of its linehaul trailers with side skirts.

Dan Carrano, director of fleet maintenance for the West Chester, Pennsylvania-based fleet, said, “We’re seeing enough success in increased fuel economy that we’ve ordered additional trailers [with skirts] for our 2014 calendar year.”

C.R. England, based in Salt Lake City and ranked No. 19, is using side skirts on a high percentage of its fleet. The refrigerated carrier also is installing 200 trailer tails from ATDynamics.

“We’ve tested [the tails] and see between a 2% to 3% improvement,” said Ron Hall, the carrier’s senior director of equipment and fuel, adding that there were two unknowns with them. The first is maintenance, as they don’t have a true benchmark yet as to how the tails hold up to wind and inclement weather. The other is getting drivers to actually deploy the tail.

Phil Braker, vice president of operations for Nussbaum Transportation Services in Hudson, Illinois, said he has good compliance among drivers with its trailer tails: “Drivers receive a bonus for saving fuel. They are going to make more money if they have that tail open.”

Nussbaum uses trailer tails from ATDynamics on about 350 trailers and will have them on 450 trailers by the end of the year.

“We will continue to do that on over-the-road trailers — anything that goes over 55 mph,” Braker said, adding that it takes about 14 months to get a return on investment.

For the past four years, No. 67 Mesilla Valley Transportation in Las Cruces, New Mexico, has been using trailer tails. Nearly all of the company’s 4,600 trailers have the devices.

“The tail is good for six to seven gallons per thousand miles,” company President Royal Jones said, adding that drivers do well with deploying the devices. “If they can reach the cord, they can do it. A person who doesn’t open the trailer tail is either lazy or didn’t do a pre-trip.”

When drivers back up to the dock, they close the tail and then open the doors. “It is creating a habit,” Jones said.

Ray Shaw, operations manager of Aerodynamic Trailer Systems, sells a trailer tail that automatically deploys. It uses a GPS and microcomputer that measures the trailer speed and deploys the tail when the trailer gets above a programmed speed. The control also automatically stows the tail when the trailer speed falls below that speed. “The advanced control also automatically detects backing up of the trailer to immediately stow the SmartTail,” Shaw said.

Vehicles traveling above 55 mph can mark a 4% to 7% increase in fuel economy with a tail, which sells for $2,500. “The average ROI is less than 10 months,” Shaw said.

One of the biggest gains NFI has seen from aerodynamics is tightening the gap between the tractor and trailer.

Utility’s Bennett said carriers are closing the gap between the tractor and trailer, trying to get it to 27-28 inches from the back of the faring on the tractor to the front of the trailer.

“With the price of fuel today, people are trying to get it as tight as they can get it,” he said.

“We spec our tractors and our kingpin plates on our trailers to get a small gap. The less space you have between the two, the less air that can get in there,” Bliem said.

NFI also uses air tabs that “go across the back of the trailer and along the roof, and they break up the vortex of air. They stick on the trailer with a double-sided tape,” Bliem said, adding that NFI tested the tabs for about two years. Older trailers are being retrofitted with them, and they are being installed on new ones. The tabs cost about $150 to $200.

The ROI of any device depends on a carrier’s tractor-trailer ratio. “We have two trailers for every truck. That is a big difference,” Nussbaum’s Braker said.

Mesilla’s Jones said, “You may have a 4-to-1 trailer [to tractor] ratio. That means you have to spend money on four trailers to feel it on each trip.”

While the savings may not be as big, aerodynamic mudflaps are gaining in popularity among carriers.

Bliem said NFI has been using them since 2008: “We purchase Andersen Eco-Flaps new on our factory builds on all of our trailers and tractors.”

He said the flaps provide a fuel savings of 1% or less.

Andersen Flaps Inc., which makes the Eco-Flap, estimates carriers can see up to a 3.5% improvement on miles per gallon. More than 100,000 tractors and trailers in North America run with Eco-Flaps, company President Barry Andersen said.

Nussbaum has been using V-Flaps, made by Mudguard Technologies, on its vehicles for about three years. But quantifying the exact savings has been difficult.

“We know it can’t be a lot and it is hard to measure, but we know it is there,” Braker said.

Mudguard President Tarun Surti said carriers typically see fuel savings of 0.5% to 1%. He added that it usually takes fleets less than a couple of months to see a return on investment with V-Flaps, which cost $20 each.

Aerodynamic mudflaps from Vortex Splash Guards Technology Inc. cost about $15 each. They incorporate a series of overlapping, angled vents that allows air, spray and road grime to flow through the mudflap and down to the ground while reducing drag, CEO Mark Morin said.

Surti said aerodynamic flaps originally were designed to minimize road spray from wet roads. “The visibility is much better with the aerodynamic mudflap,” he said.

“We went out and videoed trucks on wet, rainy roads, and there is definitely a [safety] benefit to that,” Nussbaum’s Braker said.

NFI also has seen decreased maintenance from using Eco-Flaps.

“We don’t replace these things like a regular mudflap, and there is little to no maintenance expense,” NFI’s Bliem said.

Eco-Flaps are designed to last five years, have a two-year warranty and provide carriers with an ROI after 10,000 miles, Eco-Flaps’ Andersen said.

Bliem said, “We have a bunch of the Eco-Flaps that we’ve had for three to four years in our inventory. We haven’t used because we haven’t had to replace them.”

Surti said V-Flaps typically last three years. “This product is manufactured with a specialty plastic material,” he said.

Not everyone is enamored with the aerodynamic flaps. Hall said C.R. England “saw an improvement, but [it] wasn’t significant enough to justify the expense compared to what we spend on a standard mudflap,” which costs about $6, Hall said.

However the carrier has seen a benefit from Deflecktor wheel covers, which control airflow around wheels.

“Our estimated return is [0.7%],” Hall said. “We’re purchasing those in thousand-unit batches. We’re on our second thousand right now and have decided to expand from tractor to trailer.”

Jeff Benson, Deflecktor Aero vice president, said the wheel covers can result in a 2% fuel-economy benefit when they’re installed on tractors and trailers. Carriers can see an ROI in four to six months, and the covers have a life expectancy of 750,000 miles.

There also is an undercarriage product made by Aerodynamic Trailers Systems. The company said the device is approved by the Environmental Protection Agency’s SmartWay program. When paired with trailer tails, the device offers a 5% fuel savings, the company said.

Taking weight out of the trailer also improves fuel economy.

“You burn 0.2% more fuel for every 300 pounds of weight,” Bennett said, adding that Utilities dry vans are about 300 pounds lighter than similar trailers.