Research data on pavement particle emissions for D6.5

The levels of particles generated by the circulation of the carousel wheels on the different pavements were evaluated in two complementary ways: through mobile or static measurements.

The static measurements correspond to the particles aspirated laterally from the wheels (at a height of 0.15 m and 1.0 ± 0.5 m from the central path of the tread) using an ELPI analyzer. This analyzer provides access to both ultrafine (number-weighted data) and micrometer (volume-weighted data) particle concentrations every second. The ELPI analyzer operates on the principle of electrical impaction. The aspirated particles are electrically charged, separated according to their aerodynamic diameters, and then their impact on the dedicated plates of the analyzer generates an electric current that, after amplification, allows them to be detected and classified by size (between 7 nm and 4 µm). The total volume-weighted concentrations were derived numerically from the number concentrations. Due to the turbulence induced by the passage of the wheels, it was assumed that the samples were relatively homogeneous.

The mobile measurements were based on the use of a Promo 2000 particle analyzer (from PALAS). It is a white light optical analyzer that counts particles between 200 nm and 10 µm following light diffraction at 90°. The analyzer was mounted on one of the arms of the carousel in order to measure every second the level of particles generated behind the wheel (at a distance of 0.10 m from it and at a height of 0.10 m) during the passage of different sections. The aspiration speed was of the same order of magnitude as the air flow behind the wheel (< 20% of the rolling speed): about 6 km/h. A custom-made device was added to the system to mark the moment of passage of the instrumented arm at the beginning of the S1 pavement. It was used to locate the periods of circulation of this arm on the different sections (S1, S2, S3 and S4).