Measurement of the on-road wind environment in channelled roadways

Abstract

A road test was undertaken to characterize the complex wind environment experienced by vehicles in channelled roadways. Channelled roadways consist of highways that are bordered by forests, hills, or other terrain features. A test vehicle was outfitted with three fast-response pressure probes in front of the vehicle located at 1 m, 2 m, and 3 m above the ground. Measurements were acquired on three highway routes in Canada with varying degrees of surrounding terrain, roadside forest cover, and in different wind conditions. Reference wind conditions were established using a network of federally-managed weather stations. The study identified that the effects of terrain and roadside forests can cause changes in wind direction of more than 50∘ to 90∘ relative to nearby reference weather stations. Directional channelling of winds was observed in forested and complex terrain, where changes in the wind direction mimicked the changes in highway alignment. The on-road video files were analysed using a machine-learning algorithm to quantitatively assess road-side forests and terrain and to identify fully-channelled sections of highway. Generalized channelled-flow trends were identified by considering the wind conditions in the channelled sections of all three routes. A linear relationship between the flow direction in the channel to that of the reference conditions was observed when the reference wind direction and the highway was within ±50∘. As the reference wind direction approached perpendicularity to the channelled segments, greater variations in the on-road wind direction were observed due to the unsteady flow within the channel. On-road wind speeds on each route were a maximum when the reference wind direction was approximately aligned with the highway and decreased to approximately 20% of the reference wind speed when the reference wind was perpendicular to the channel.