Trailer fairings, frequently referred to as trailer skirts, are the most popular devices for addressing aerodynamic drag on trailers. They prevent wind from ducking in under the trailer and running into the trailer bogie. Fleets and drivers see fewer challenges in operational environments with skirts, as they do not interfere with moving freight in and out of dry van trailers.
Skirts are most effective when they extend from the landing gear to the front face of the front trailer axle and are as low to the ground as possible. Depending on the terrain covered by a particular duty cycle, the skirt may need to be shorter.
The majority of skirts on the market today are flat sheet materials—composite, metallic, or both—bracketed to the underside of the floor structure of the trailer. Formed or molded panels are also available. Various manufacturers include a rubber flexible strip at the bottom of the skirts to help close the gap between the ground and the bottom edge of the skirt. Skirt reliability, durability, and cost have improved over the last five to seven years.