Emission testing of diesel multiple units complying with different emission standards during real operating conditions

This article presents comparative studies on pollutant emissions from railbuses meeting different emission standards (Stage IIIA and Stage IIIB). Measurements were conducted under real-world operating conditions on routes regularly serviced by the tested vehicles during passenger operations. The obtained results enabled the evaluation of vehicle operating conditions and propulsion systems, the assessment of emission intensity as a function of driving parameters, the determination of road-specific and unit-specific emission factors, and comparisons with homologation limits. The vehicle compliant with the newer emission standard demonstrated a reduced environmental impact, particularly regarding particulate matter emissions. Object A achieved 0.03 g/km and 0.005 g/kWh in the test, while the second object achieved 0.14 g/km and 0.03 g/kWh. Significant differences were also recorded for CO. The object with the higher approval standard achieved a CO emssion of 9 g/km and 1.36 g/kWh. For vehicle B, obtained 14.71 g/km and 3.22 g/kWh respectively. However, the analysis revealed that selected toxic compounds exceeded legislated limits during testing. The tested vehicles exceeded the permitted NOx and HC pollutant emission standards by between 5% and 50%.