Keywords: calm meteorological conditions, heterogeneous traffic, line source models, traffic generated turbulence, urban hotspots, vehicle wakes, wind speed correction factor, wind turbulence, urban transport, pollution dispersion, wind velocity, traffic movements, air quality, air pollution, Delhi, India
Vehicle wake factor for heterogeneous traffic in urban environments
Vehicles' 'wakes' are generated as a result of vehicular movements. They are one of the dominant factors in dispersing the pollutants in 'calm' meteorological conditions when wind velocity is <1 m/sec (Chock, 1978). They are used as a wind-speed-correction factor in several air quality models considering the effects of traffic movements on the pollutant dispersion. In this study, the vehicle wake factor (VWF) has been estimated using the inverse general finite line source model, GFLSM, (Luhar and Patil, 1989) for heterogeneous traffic conditions at one of the busiest traffic intersections of the Delhi city, near the Income Tax Office (ITO). The results show that in 'unstable' conditions, the VWF varies between 1.63 and 0.3 (for wind direction, θ = 90?) and 2.5 and 0.8 (for wind direction, θ = 180?). During 'neutral' and 'stable' conditions, it is in the range of 0.84?0.4, 1.91?0.85, (for wind direction θ = 270?) and 1.7?0.7, 3.1?0.3 for wind direction θ = 360?, respectively.