Lead and cadmium are heavy metals and are regarded as traffic generated pollutants scattered in the urban environment through vehicular traffic flow. A total of 13 roads in the city of Isfahan were used for studying the roadside soil pollution amount and determination of effective traffic parameters on soil lead and cadmium amounts. Soil samples were collected and analyzed from 13 sites. An empirical statistical approach was employed for the analysis and modeling purposes. Results suggest that Lead and Cadmium mean concentrations within the distance of 50 m from road curbside are more than background values. These values are well-above the maximum acceptable concentration of heavy metal contents of agricultural soil. Regression analysis of metal concentrations in gutter soil showed that the most effective traffic parameter which affects soil metal concentrations is total traffic volume. It was also observed that Lead and Cadmium concentrations (as independent variables) decreased logarithmically as distance increased from road curbs (as dependent variable), but they decreased exponentially with increment of total traffic volume (as another dependent variable). The regression models developed in this research are used for estimation of Lead and Cadmium concentrations in urban roadside soils on the basis of the distance from road and total traffic volume. The outcomes of this research can be used for mitigation of environmental impacts of roads by using them in urban land use planning, urban design, urban transportation and road traffic management and control.
