Side Skirts for Tractor Trailers
to Increase Fuel Efficiency
Whether they are called side skirts, air dams,
fairings, side fairings or truck fairings, we
are referring to the devices that are
installed under the sides of big truck trailers to reduce wind
resistance (or air drag) and
Many professional drivers are familiar with fairings
on the backs of their tractors to reduce wind resistance between the
tractor and trailer or the low tractor fairings most often covering the
previously wrote about aerodynamic wheel
covers as a means of
increasing fuel efficiency.
Here are what some websites have to say about
"Advanced Trailer Skirts" were one of the "Verified Aerodynamic Technologies" listed on the EPA's SmartWay Technology page.
document from the EPA says that side skirts are "panels
down from the sides of a trailer at the bottom edge to enclose the open
space between the rear wheels of the tractor and the rear wheels of the
article on AllBusiness.com entitled "Aerodynamic
Tractor-Trailers May Become the Rule in California" quoted SmartWay
transport manager Mitch Greenberg as indicating that "side skirts
improve fuel economy by 4%."
In March 2009, FleetOwner.com quoted Andrew
Smith, CEO, ATDynamics as saying, "Trailer aerodynamic
devices have gone from being fringe products to accepted, mainstream
components all due to the dramatic fluctuations in fuel prices we've
An article stated the following
about two new skirts
"that accommodate larger wide-base tires" being revealed at the 2010
Mid-America Trucking Show in Louisville, Ky:
"Produced by the Utility Trailer
both designs are verified through the Environmental Protection Agency
(EPA) SmartWay program and the California Air Resources Board (CARB) as
meeting governmental fuel efficiency standards."
One of the products is said to provide a 4
savings in fuel,
other 5 percent.
Utility Trailer's website
features a video
and .pdf document with all of the
details about their products.
Another .pdf document from Utility
overview of the side skirts' bracing system that allows them to flex
both inward and outward.
At one time, Great
Dane Trailers' website listed these "Aerodynamic
Trailer Side Skirts" first among numerous products that
are optional for their new or retrofitted trailers.
Natural Resources Canada [NRC] website provides details on
select a trailer aerodynamic device." A photograph on their site
reveals that the product they describe is slightly different from those
most often seen in the USA.
NRC says, "Trailer side skirts are a set of
that run the length of the trailer to extend it closer to the ground."
The devices "provide a 4 to 7 percent fuel savings by minimizing the
air flow under the trailer and around the back axle." There is also a
chart showing the average payback period.
A TruckingInfo.com article quoted a
truck owner who installed Windyne skirts on his trailer and "says they
save 8.94 percent in fuel."
An April 22, 2008 article on ScienceDaily.com
states, "Creating an improved aerodynamic shape for truck trailers by
mounting sideskirts can lead to a cut in fuel consumption and emissions
of up to as much as 15%."
Vicki was delighted to find that numerous trucking
companies have decided to implement these aerodynamic devices on their
trailers. Let's take a look.
This rig is operated by
Salson Coast to Coast.
A close-up of the skirt
reveals that this is a US EPA Certified SmartWay Trailer.
This is an ultra close-up of
the seal that the side skirt bears.
A Landstar trailer sports its
aerodynamic trailer side skirt.
This Prime Inc trailer has
one installed behind the fuel tank for the trailer's refrigeration unit.
This close-up shows the
clearance behind the reefer's fuel tank.
Whereas the skirt shown on
Prime trailer above has sloped sides, the one shown here has pointed
sides. We're not sure, but it appears that the fairing may extend a
little closer to the ground than the one above.
This J.B. Hunt trailer
features a side skirt.
Up until taking this photo,
writing we've seen on skirts is the EPA certification. This Trans West
trailer's skirt is printed.
Here's a close-up of the
Trans West side skirt. We wouldn't be surprised if some day in
future, this turned into advertising space.
Please notice that some trailer skirts (whether shown on
this page or on linked pages) have different configurations. We noted
the skirts' edges above. Of particular note to us is the straight (in
the sides of the trailer) versus sloped (narrower toward the front of
the trailer and fanning out toward the sides of the trailer toward the
rear) installation. We would be interested in knowing which
configuration works best to reduce the most wind resistance.
We would also be interested to read drivers' experience
in using different brands of trailer skirts. Which skirt resists cracks
and breaks, holds up under temperature and humidity changes, lasts
longest and in
general works the best?
Money saving tip: Any
device used on a vehicle to reduce wind resistance or air drag will
help improve that vehicle's fuel efficiency. There is absolutely no
tractor trailer side skirts or air fairings accomplish both.
Professional drivers who own their own trailers
would do well to
calculate the ROI (return on investment) that purchasing and installing
these devices will provide. While costs may vary between brands, one
"With the cost
of the Windyne Flex-Fairings being $4,600 U.S. ($5,000 Canadian), it
will take approximately 13.6 months to pay for the fairings. With an
expected life cycle of 10 years, my total dollar savings (at today's
fuel prices) will be approximately $39,000."
Overdrive Online uses the "default
prices of around ... $1,800 for side skirts" for which they say "the
EPA estimates a payback of about a year...in fuel savings alone."
Notice, too, that the payback period range (shown
graphically on the NRC website) shows two different
types of skirts:
standard and advanced. The EPA's website provides a list of SmartWay verified technologies and
devices, including those classified as one of these two types
In some places, incentives (such as a grant)
may be available to
help drivers purchase trailer skirts. If you are interested,
investigate all opportunities and take
advantage of the one that works best for you.
Be aware that some locations may require
drivers to have these devices installed on their trucks before they can
enter. Know ahead of time what restrictions are involved before you
make the trip.
When you calculate your ROI, be
aware that your driving habits also affect your fuel savings.
Furthermore, determine if the quoted cost of the