Characterization of emissions from axle-mounted rail disc brakes

The most important sources for non-exhaust emissions from railways are the contact strip, the contact wire, wheels, rails and brakes. It is expected that the major share of PM (particulate matter) emission can be assigned to the brakes. In order to quantify the emissions from railway brakes, a series of test bench tests was carried out. These tests aimed at a quantification and characterization of emissions for both sintered and organic brake pads. The measurement setup included monitoring of emitted particle mass and particle number (PN) in the size range from 10 nm to 32 µm. PM10 emission factors could be derived in the range from 0.11 g/km to 4.21 g/km. Emissions from organic brake pads were higher compared to those from sintered materials. The monitoring of particle number concentration showed a significant dependency of PN emissions from the surface temperatures as soon as a critical temperature was exceeded.