Impacts of traffic heterogeneity on roadside air pollution concentration

Crude representations of traffic parameters (e.g., speed, queue length) are major limitations in the existing on-road vehicle emission and air quality models (e.g., US Environmental Protection Agency’s CALINE models). Here an alternative approach is offered consisting of a cell-transmission recipe traffic propagation model to capturing time-dependent vehicular traffic characteristics and a Gaussian dispersion model to estimate traffic emissions and roadside air quality estimation. The cell-transmission approach is consistent with the current air dispersion models when traffic is homogenous. When traffic is highly variable in terms of speeds and densities, the new approach is sensitive to the spatial and temporal heterogeneity of traffic. The model also suggests high carbon monoxide concentrations at intersections during the off-peak traffic hours, resulting in significantly longer exposure to high level pollutants at an intersection.