Evaluation Research Of Automobile Emissions For Different Highway Geometric Design

Highway is the important infrastructure of national economy and social development,at the same time,the motor vehicle emissions of highway operation also brought a series of environmental pollution problems.To solve the problem,currently use vehicle own emissions technology to reduce the negative impact of the highway transportation on the environment.Studies show that motor vehicle emissions are related to road design elements(design speed,road grade,grade,etc.).However,the research regarding the reduction of the adverse impact through highway geometric design is still in its infancy.This research generated second-by-second speed profiles using the speed prediction models and non-uniform acceleration/deceleration models,and extracted different geometric alignment VSP distribution,based on motor vehicle emission simulator(MOVES)to calculate the fuel consumption and emissions rates,build quantitative relationships between highway alignment and fuel consumption and emissions.Finally,the comparison of the design of the highway line condition and under the condition of minimum standards of fuel consumption and emissions,and the comparison results expressed by the environmental assessment factor(EMFs)represented in the form of ratio.The results demonstrated that fuel consumption and emissions could be significantly changed according to highway geometry conditions.For longitudinal slope design,contrast trucks run on 0% and 9% of the slope,the latter CO,HC and PM2.5 emissions nearly five times higher than the former,CO2 and NOX emissions three times higher.Gradient significantly affects the fuel consumption and emissions.In the design of vertical curve,When the curvature of the simulation value increases 50%,the fuel and CO2 consume less 1%,CO and HC decrease 17% and 18% respectively,the change of PM2.5 is not obvious.To environmental assessment found that the smaller the radius,the emissions and fuel consumption will increase.When curve radius reduced 50%,the design automobile fuel consume 5% more than the minimum.