Determinants of rear-of-wheel and tire-road wear particle emissions by light-duty vehicles using on-road and test track experiments

Abstract

The purpose of this study is to identify the parameters governing particle emissions at the rear of the front wheel of an instrumented light-duty vehicle. The information obtained from the road is complemented by data acquired on a test track. By comparing the signals recorded at various locations around the vehicle, a distinction can be drawn between rear of the wheel particles (RoWP) and particles resulting from tire and road wear (TRWP). Both types of emissions are highly dependent on driving speed. TRWP mainly fall in the size ranges of <0.03 μm and 0.05–0.30 μm by their number, and 0.1–0.6 μm and 1.0–15 μm by mass when using a mean density of 2.0 g/cm3. Within these ranges, TRWP account on average for 40% and 25% of RoWP emissions, respectively. We also evaluate herein the influence of: i) pavement contamination by particulate matter, ii) road geometry, iii) driving area, and iv) structural elements affecting road traffic. Test track experiments finally provide information on the significance of accelerations, decelerations, pavement texture and age. This knowledge compilation may be implemented in future non-exhaust particulate emissions standards; moreover, it establishes a basis for realistically assessing emission dynamics and identifying affected areas.