Grabe, Ruan JohannesJoubert, Johan W.2022-12-062022-12-062022-11Grabe, R.J. & Joubert, J.W. 2022, 'Are we getting vehicle emissions estimation right?', Transportation Research Part D: Transport and Environment, vol. 112, art. 103477, pp. 1-13, doi : 10.1016/j.trd.2022.103477.1361-9209 (print)1879-2340 (online)10.1016/j.trd.2022.103477https://repository.up.ac.za/handle/2263/88663Simulation is a valuable prediction tool to evaluate the impact of climate change interventions prior to disruptive implementations that may yield unintended and unwanted consequences. Advances in agent-based simulation allow us to estimate the dynamic emissions produced by vehicles at a fine resolution, with each vehicle modelled individually. The scalability of these models allow decision-makers to evaluate large-scale scenarios. But how good are these models? In this paper, the authors apply a state-of-the-art emissions model in the Multi Agent Transport Simulation (MATSim) framework to simulate individual vehicle emissions. Simulation results are compared with real driving emissions tests, using a portable emissions measurement device on a light and heavy vehicle. Quantifying the gap between macro-level simulation and actual emissions, the paper contributes by showing that pollutants are significantly underestimated, especially for heavy vehicles. This confirms prior micro-scale studies and magnifies the detrimental impact of using uncorrected aggregated models to inform environmental policy affecting transport.en© 2022 The Author(s). Published by Elsevier Ltd. This is an open access article under the CC BY license.Agent-based simulationPortable emissions measurement system (PEMS)Real driving emissions (RDE)Article