A Study of the Spatial Variation of Vehicle-Induced Turbulence on Highways Using Measurements from a Mobile Platform

During July 2016, an on-road study was conducted in and around the Toronto, Canada region to investigate the spatial variation of vehicle-induced turbulence on highways. The power spectral density of turbulent kinetic energy (TKE) while following on-road vehicles is significantly enhanced for frequencies greater than 0.5 Hz. This increase is not present while driving isolated from traffic, demonstrating that TKE is enhanced considerably on highways in the presence of vehicles. The magnitude of normalized TKE is found to decay following a power-law relationship with increasing normalized distance behind on-road vehicles, which is most pronounced behind heavy-duty trucks. The results suggest that the TKE in the vehicle wake is maximized in the upper shear layer near the vehicle top. An extended parametrization is outlined that describes the total on-road TKE enhancement due to a composition of vehicles, which includes a vertical dependence on the magnitude of TKE.