An Examination of Vehicle Spacing to Reduce Aerodynamic Drag in Truck Platoons

Aerodynamic drag is a significant source of energy dissipation in tractor-trailers, accounting for as much as 20% of energy lost at high speeds. Despite a growing interest in automation techniques, few studies exist on truck platoons with a focus on inter-vehicle spacing. In this work, experiments are conducted to estimate the drag coefficient of 2- and 3-member platoon combinations of medium-duty Volvo VNL-300 day-cab trucks. The relative drag of the leading, middle and trailing trucks is compared by recording the axial drag forces on 1/64 scale models in a wind tunnel. The average drag coefficient ratio shows that drag-reductions of around 36% are possible at inter-vehicle spacing distances of 3m for full-scale 2-truck platoons with each tractor-trailer combination including a scale-similar 53-ft wedge trailer.