Carbon Emissions and Expressway Traffic Flow Patterns in China

Yaping Dong,Zhihao Duan,Chao Gao,Xingliang Liu,Jinliang Xu,Han Ru

doi:10.3390/su11102824

Abstract

Traffic flow patterns severely impact vehicle carbon emissions. A field test was conducted in this study to obtain fuel consumption and traffic volume data under various traffic flow patterns and to explore the relationship between traffic flow patterns and vehicle carbon emissions. Carbon emission data were obtained via the indirect carbon emission accounting method proposed by the Intergovernmental Panel on Climate Change. Carbon emission prediction models for diesel trucks and gasoline passenger cars were established respectively with volume to capacity ratio as an explanatory variable. The results show that carbon emissions are highest under the congested flow conditions, followed by unstable flow, free flow, and steady flow. The relationship between the volume to capacity ratio and carbon emissions is a cubic curve function. The carbon emissions of trucks and passenger cars with a volume to capacity ratio of 0.4 to 0.5 are relatively small. The proposed carbon emissions models effectively quantify the carbon emissions of vehicles under different traffic flow patterns. The results of this study may provide data to support and a workable reference for expressway operation management and future low-carbon expressway expansion construction projects.

Highlights

Traffic flow patterns affect the operating conditions of individual vehicles
Scholars dedicated to this subject have established various micro carbon emission models including Mobile Source Emission Factor Model (MOBILE) [5], Comprehensive Modal Emissions Model (CMEM) [6], and Motor Vehicle Emission Simulator (MOVES) [7] designed to reflect the real-time operating conditions of vehicles
Researchers have sought to define the rule of partial exhaust emissions (CO, HO, NOX) in congested traffic conditions, but have made no quantitative analysis of carbon emissions to date despite the fact that fuel consumption is closely related to traffic flow [1,2]

Summary

Introduction

Traffic flow patterns affect the operating conditions of individual vehicles. Vehicle operating conditions, in turn, are closely related to fuel consumption and carbon emissions [1,2,3,4]. To this effect, there is an important relationship between traffic flow conditions and carbon emissions. Research on the effects of traffic flow patterns on vehicle operating conditions has revealed a close relationship between traffic flow conditions and fuel consumption [1,2,3]. The carbon emissions of vehicles in congested traffic flow were 10–200% higher than those in free-flow traffic conditions. Researchers have sought to define the rule of partial exhaust emissions (CO, HO, NOX) in congested traffic conditions, but have made no quantitative analysis of carbon emissions to date despite the fact that fuel consumption is closely related to traffic flow [1,2]

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Conclusion