Prediction of CO ₂ Emissions from Light-Duty Vehicles Based on Highway Alignment

In order to allow for the precise prediction of the CO₂ emissions of light-duty vehicles during the road design phase and to methodically examine the effect of road alignment on CO₂ emissions, this paper classifies the operating conditions of light-duty vehicles according to Vehicle Specific Power (VSP) and the design speed of different road levels. The test vehicle’s environmental data and operational parameters under various road conditions were gathered using a Portable Emission Measurement System (PEMS). The CO₂ emissions of the test vehicle under different operating conditions were statistically analyzed. Based on the road’s horizontal and vertical alignment, the road was separated into analytical units, including straight sections, longitudinal slope sections, horizontal curve sections, and curve-slope combination sections. The indicators of each analysis unit were used to anticipate the speed and acceleration of light-duty vehicles in each unit, and a model for forecasting light-duty vehicle CO₂ emissions based on road alignment was developed. The results show that the predicted CO₂ emissions based on road alignment have a relatively small error compared to actual emissions, indicating high model accuracy. This model enables relatively accurate predictions of CO₂ emissions for light-duty vehicles on target road sections during the road design phase. Among the various road alignment indicators, slope has a greater effect on the test vehicle’s CO₂ emissions.