The vehicle emission is an important effectiveness measurement of any sustainable transportation development. Geometric and surface characteristics of pavement play an important role in reduction in fuel-economy and greenhouse gas emission. Deterioration of pavement surface is considered as the basic problem, which increases in fuel consumption, which leads to increase in emissions. The aim of the present research work is to provide better understanding on the role of pavement characteristics in green transportation initiates. Evaluating the effects of these emissions based on the roughness characteristics and the effect of gradient is the objective of the research. The field data collection surveys were conducted on two stretches in and around OU campus, viz., (i) OUCT road and (ii) DD colony A-lane. Roughness measurement surveys were conducted on these selected stretches by using MERLIN. The vehicular emissions of Alto and Swift petrol cars were measured by using AVL Di-gas 444 analyzer. Comparisons were made for emissions on these different stretches against roughness and gradient of these two roads. The comparisons show considerable percentage increase in emissions on the stretches with higher roughness and gradient. As the objectives intended, the impact of pavement roughness on vehicular emission is related to roughness and gradient and the regression equations were developed to estimate four types of vehicular emissions. Based on the impact of gradient on vehicular emissions, the geometric design engineer can adopt the minimum level of gradient to be used while designing new roads.