Measurement And Application Of Carbon Emissions Throughout The Life Cycle Of Highway Longitudinal Slope Sections

In recent years,reducing carbon emissions from road transportation has become a hot topic in the field of transportation.Scholars from various countries around the world have conducted research on carbon emissions during the construction,operation,and maintenance stages of the entire life cycle of highways,and have achieved positive results.However,the geometric parameters of highways,especially longitudinal slopes,directly affect the scale of engineering construction,and the longitudinal slope parameters will have a long-term impact on vehicle operating quality and carbon emissions after construction is completed.Surprisingly,the influence of longitudinal slopes on the life cycle carbon emissions has not received sufficient attention.Therefore,it is necessary to study the influence of longitudinal slope parameters on the life cycle carbon emissions of highways,and to provide theoretical support and technical references for the design of low-carbon highways.Through literature research,this study comprehensively analyzed the sources of carbon emissions throughout the life cycle of highways,defined the accounting scope of carbon emissions for longitudinal slope sections of highways,and established a relatively complete database of carbon emission factors for longitudinal slope sections of highways using a database retrieval method.The study also analyzed the factors that affect the carbon emissions of longitudinal slopes on highways,and established a carbon emissions calculation model for longitudinal slope sections of highways that takes into account the carbon emissions sources at different stages,providing a calculation method for analyzing the life cycle carbon emissions of highways.Based on actual engineering analysis,the study also revealed the influence of different longitudinal slope design standards on the life cycle carbon emissions of highways.The results of the study show that:(1)The carbon emissions of longitudinal slope sections throughout the life cycle mainly come from the construction and operation stages.Unlike the construction stage,the total carbon emissions during the operation stage gradually increase with the increase of usage years,and will exceed the carbon emissions during the construction stage within a limited number of years(depending on traffic volume,based on 10 years for the engineering).(2)With the increase of the longitudinal slope design standard,the life cycle carbon emissions of highways increase.Among them,the carbon emissions during the construction stage increase,while the carbon emissions during the operation and maintenance stages decrease.For continuous longitudinal slope sections,when the average longitudinal slope is increased from 2% to 3%,the life cycle carbon emissions of the longitudinal slope section decrease by 7.5%,among which the carbon emissions during the construction stage decrease by 29%.Further analysis shows that bridge and tunnel engineering accounts for up to87% of the carbon emissions during the construction stage of highways,and the decrease in bridge and tunnel engineering caused by the increase of longitudinal slope is the main reason for the decrease in carbon emissions during the construction stage.When the longitudinal slope parameter is increased from 2% to 3%,the carbon emissions during the operation stage only increase by 3.3%.Although the increase in percentage is not large,it cannot be ignored due to the large base amount of carbon emissions during the operation stage.The research results provide references for the design of low-carbon longitudinal slopes on highways and provide a basis for highway management departments to determine the timing of road maintenance throughout the life cycle.