A field test study of airborne wear particles from a running regional train

Abstract

Inhalable airborne particles have inverse health effects. In railways, mechanical brakes, the wheel-rail contact, current collectors, ballast, sleepers, and masonry structures yield particulate matter. Field tests examined a Swedish track using a train instrumented with particle measurement devices, brake pad temperature sensors, and speed and brake sensors. The main objective of this field test was to study the characteristics of particles generated from disc brakes on a running train with an on-board measuring set-up. Two airborne particle sampling points were designated, one near a pad-rotor disc brake contact and a second under the frame, not near a mechanical brake or the wheel-rail contact; the numbers and size distributions of the particles detected were registered and evaluated under various conditions (e.g. activating/ deactivating electrical brakes or negotiating curves). During braking, three speed/temperaturedependent particle peaks were identified in the fine region, representing particles 280, 350, and 600 nm in diameter. In the coarse region, a peak was discerned for particles 3-6 mm in diameter. Effects of brake pad temperature on particle size distribution were also investigated. Results indicate that the 280-nm peak increased with increasing temperature, and that electrical braking significantly reduced airborne particle numbers. Field emission scanning electron microscope images captured particles sizing down to 50 nm. The inductively coupled plasma mass spectrometry results indicated that Fe, Cu, Zn, Al, Ca, and Mg were the main elements constituting the particles.

Particle Emissions From Rail Traffic: A Literature Review

“…As it was investigated by Hill and Gooch, the push-train arrangement for diesel trains will reduce the UFP concentration inside the train. Besides, an increased application of electric brakes diminishes the use of mechanical braking and thus the emission of particles as found by Abbasi (2012a). Particle concentration levels in the Stockholm subway have shown a decreasing trend the last 10-15 years.…”

“…The actual ventilation arises as a consequence of the interaction of ventilation system design, supply air, enclosure design, tunnel and train design, and climatic conditions. Furthermore, meteorological conditions, instrument specifications and characteristics, and measurement techniques are additional factors that influence the outcome of measurements for both exhaust and non-exhaust emissions (Maricq, 2007;Nieuwenhuijsen et al, 2007;EPA RIN 2060-AM06, 2008Salma, 2009;Abbasi et al, 2012a). It is very important that researchers consider all of those effective factors in the future field studies or laboratory tests and report them in their work in order to achieve more repeatable and applicable results.…”

“…The number mode for coarse particles has been reported in the 2-7 µm range Lorenzo et al, 2006;Salma, 2009;Abbasi et al, 2012a). The fine region with the highest particle number frequency was in the 250-650 nm diameter range (Seaton et al, 2005;Gustafsson, 2009;Abbasi et al, 2011;Fridell et al, 2011).…”

“…Nearly all coarse non-exhaust particles have flake shapes (Salma, 2009;Abbasi et al, 2012a, b;Sundh and Olofsson, 2011), whereas the fine and ultrafine particles are spherical, semi-spherical, or ellipsoidal in shape (Lorenzo et al, 2006;Abbasi et al, 2012a;Sundh and Olofsson, 2011). It is suggested that differences between the dominant wear mechanisms cause the differences in wear particle shape (Stachowiak et al, 2008).…”

“…Moreover for particle concentrations also ventilation conditions largely determine concentration levels. Furthermore, meteorological conditions, instrument characteristics, and measurement techniques are additional factors that influence the outcome of measurements for both exhaust and non-exhaust emissions (Maricq, 2007;Nieuwenhuijsen et al, 2007;EPA RIN 2060-AM06, 2008Salma, 2009;Abbasi et al, 2012a).…”