Development of air pollutant emission factors under real-world truck driving cycle

The truck driving cycle was developed in Thailand using actual speed-time profile from trucks in suburban area. Driving data were separated into micro trips and the representative driving cycle was selected by matching micro trips statistics and target statistics. The Performance Value (PV) was considered for selecting the representative driving cycle. This selected driving cycle was then used as input data for estimating emission factors of 4 air pollutants and 3 greenhouse gases by the International Vehicle Emission (IVE) model. Results were then compared with emission factors developed using the European Transient Cycle (ETC). Additionally, a comparison was made between emission factors calculated in this study and direct measurements of emissions from truck driven on chassis dynamometer under the European driving cycle. Comparison results revealed that CO, NO_x and CO₂ emission factor were about 2.05, 2.24 and 1.78 times lower than those obtained from direct measurements. PM emission factor was about 0.89 times higher than measured data. This study confirms the need to considered actual fleets and characteristics of vehicular sources when calculating their emission rates for further use in development of emission inventory.