Effect of train velocity on the amount of airborne wear particles generated from wheel-rail contacts

Railways are considered as an environment friendly transport system. However, railway transportation produces airborne wear particles (AWPs) from the brake systems, wheel-rail contact, contact-strip-overhead-contact-wire contact, and third-rail contact, which have adverse effects on human health. The generation of AWPs from wheel-rail contact has hardly been studied. In this study, we used a twin-disc rig to investigate the generation of AWPs from both rolling/sliding and pure sliding contacts at different train velocities. AWP number concentrations (AWPNCs) were measured at three different train velocities, i.e., 28, 45, and 90 km/h. The measurement was done using two particle counting instruments, a fast mobility particle sizer (FMPS) that measures particles in the range of 5.6-560 nm and an optical particle sizer (OPS) that measures particles in the range of 0.3-10 µm. AWPNCs were analyzed as a function of slip rate. AWPNCs measured by both the instruments and by FMPS continued to increase with slip rate at 28 and 45 km/h, respectively. AWPNCs measured by OPS and by both instruments increased during a rolling/sliding contact and then decreased during a pure sliding contact at 45 and 90 km/h, respectively. The total and maximum AWPNCs measured by both instruments increased with an increase in the train velocity. Furthermore, size distribution analysis showed that the AWPNCs for the peak particle diameter increased with an increasing train velocity. These results indicate that train velocity has a significant effect on the generation of AWPNCs.