Trailer skirts comprise a pair of panels affixed to the lower side edges of a trailer, running most of the length of the trailer and filling the gap between the forward and rear axles. Trailer skirts are typically constructed of aluminum, plastic, or fiberglass, with plastic the most resistant to damage from side or bottom impacts. Skirts may have a modular design, allowing installation on a variety of trailer lengths. Skirts may weigh between. Installation typically requires three to five.
Cost
, a set of trailer skirts cost between C$1500 and C$3000. Standard trailer skirts have an estimated payback period of ten to eighteen months, while "advanced" skirts are estimated to pay for themselves in seven to fourteen months.
Performance
A 2012 investigation by SAE International of nine trailer skirt designs found that three provided fuel savingsgreater than 5%, and four provided savings between 4% and 5%, compared with an unmodified trailer. Skirts with reduced ground clearance offer greater fuel savings; in one instance, reducing ground clearance from to resulted in an improvement in fuel savings from 4% to 7%. One 2008 Delft University of Technology study found fuel savings of up to 15% for the particular design studied. Sean Graham, president of a major supplier of trailer skirts, estimates that in typical use, drivers see fuel savings of 5% to 6%. Trailers with skirts fitted have also demonstrated reduced tire spray, and drivers have reported improved stability in crosswinds.
Adoption
As of 2018 over 60% of new trailers produced in Australia are equipped with skirts, whereas the figure is over 50% for the North American market. A 2014 study by the North American Council for Freight Efficiency on adoption of fuel efficient technologies and practices found trailer skirts to be the most widely adopted technology of those studied, having been adopted by seven of the ten major shipping fleets in the study. Since the wide adoption of trailer skirts, the incidences of them becoming detached and hurting other drivers on the road have increased. On October 18th, 2018 in one particular case, a trailer skirt came off of an east bound tractor trailer and ended up in the west bound lanes where it hit a car and killed its driver Mark Elliot, 71, of St. Louis, Missouri while he was traveling through Knoxville, Tennessee.
