Model Development for the Real-World Emission Factor Measurement of On-Road Vehicles Under Heterogeneous Traffic Conditions: An Empirical Analysis in Shanghai

Global warming is attributed to anthropogenic emissions of CO2 and the contribution from the transport sector is significant. Estimating on-road vehicle CO2 emission factors is essential for guiding carbon-reduction efforts in transportation. In order to accurately calculate carbon emission factors from vehicles, this study built a multi-scenario model for open, semi-enclosed, and enclosed road environments based on Fick’s second law and the law of conservation of mass. During the model optimization phase, it was found that the model’s applicability domain effectively encompassed most urban roadway scenarios, making it suitable for estimating urban traffic CO2 emissions. The spatiotemporal heterogeneity analysis of field measurements indicated that this method can effectively distinguish variations in CO2 emission factors across different road types and time periods. The method proposed in this study offers an effective solution for the real-time monitoring of large-scale on-road vehicle carbon emissions.