Dispersion simulation techniques for assessing the air pollution impacts of ground transportation systems

Development of air dispersion simulation techniques for assessing the air pollution resulting from roadway vehicle emissions are discussed. Various mathematical models for air dispersion are surveyed and evaluated in terms of their applicability to estimation of pollutant concentration in the vicinity of roadways. The Gaussian steady-state dispersion model is considered in detail, and extensive field studies are used to validate this model in the region within 500 feet of the edge of both an at-grade roadway and a depressed roadway. The calibrated Gaussian model is used to formulate techniques for estimating annual one-hour and eight-hour maximum concentrations resulting from roadway emissions.