Analysis On The Features Of Carbon Emissions During The Use Phase Of Beijing Highways And Emission Reduction Measures

With the development of Beijing's transportation industry and highway network,the amount of motor vehicles and highway traffic flow has increased dramatically.Therefore,carbon emissions in the use phase of highways have become the main source of carbon emissions in Beijing.Here come such problems of traffic congestion,energy consumption and carbon emissions,making emission reduction in the use phase a top priority on the agenda.Based on a survey on the status quo of the use phase of highways in Beijing,this thesis first explores the pavement structure types and traffic flow characteristics,analyzing common road diseases and causes and maintenance techniques through field investigations,setting a foundation for the subsequent calculations of carbon emissions at the use stage.This thesis then demonstrates the feasibility of the life cycle analysis method for the calculation and analysis of carbon emissions in the use phase of highways in Beijing.The comprehensive life cycle analysis method is selected,after a comparison of three different methods.This thesis divides the use stage into two parts,the operation stage and the maintenance stage.It's clarified that carbon emissions in the operation stage mainly come from vehicles,and those in the maintenance stage mostly come from the production of maintenance materials and the operation of maintenance machines,thus having determined specific calculation method and carbon emission factors used in each stage.According to the relationship between pavement roughness and vehicle fuel consumptions,the thesis makes an analysis on carbon emissions of different types of vehicles.It is found that the carbon emissions of passenger cars accounted for 47% of the total,which have imposed the greatest impact on the total carbon emissions during the operation phase.Based on the calculation of emission reduction rate,a comparative analysis is made on the carbon emission characteristics of the highways during the operation phase with or without preventive maintenances,coming into the conclusion that preventive maintenances can reduce the carbon emissions generated by operating vehicles by 2.77%,higher than the reduction goal of a 2.5% decrease for per 10,000 yuan of GDP set for Beijing in 2018.In the analysis of the maintenance stage,the thesis focuses on the carbon emissions in the whole process of micro surfacing and thin layer overlay maintenance technologies,clarifying the carbon emissions of each part throughout the process,and having found that the carbon emissions at the material production stage take up 82.60% and 66.90% respectively for micro-surface treatment technology and thin layer maintenance technology,therefore having a larger impact on the overall emissions.A sensitivity analysis is carried out to further demonstrate the carbon emission characteristics of each part in the use phase,having found that the road conditions of the expressways have a great impact on the carbon emissions of vehicles during the operation phase of the expressways.When the International Roughness Index(IRI)increases by 20%,the vehicle fuel consumptions rise by an average of 1.63%.In the maintenance stage,if the used amount of different maintenance materials increases by 20%,the total carbon emissions of micro surfacing and thin layer overlay will grow by about 3.33% ~ 11.14%.Hence,the amount of materials has a great impact on the overall carbon emissions during the maintenance stage.Based on the carbon emission characteristics of the expressways in the use phase of Beijing,in order to better achieve the emission reduction goals of the expressways in the use phase,it is recommended to strengthen the preventive maintenance of the expressways,especially those with great loads of passenger cars and heavy-duty trucks in the operation phase;to optimize the production process to reduce carbon emissions in the stage of maintenance materials production;to applicate fine management in the construction to reduce unnecessary waste of materials and construction machinery,and choose a material production plant and construction machinery nearby to reduce carbon emissions in transportation during the construction phase for maintenance.