Abstract
Wheel out-of-roundness (OOR) and unsprung mass are key railway vehicle parameters influencing the dynamic wheel‒rail contact loads and inducing ground-borne vibration. For a given combination of vehicle speed, track/soil conditions and wheel/rail irregularity level, reducing the unsprung mass leads to a reduction in contact loads and vibration at frequencies above the resonance of the wheelset on the primary suspension. Guidelines for reducing unsprung mass are presented, including alternative designs for the wheelset and the suspension of the mechanical drive system. For locomotives and powered bogies, the potential for reduced vibration level is 2–4 dB by improving the drive suspension design. Based on an extensive field measurement campaign, where the influence of several different types of vehicle on vibration level was measured, it was found that the maximum vibration levels were generated by freight locomotives. For several freight locomotives of the same type, a high statistical variance (up to 20 dB) in measured vibration level was observed indicating a significant spread in wheel tread conditions and OOR. Early detection of out-of-round wheels and corrective wheel maintenance are important measures to reduce vibration levels.
Acknowledgements
The three-year project RIVAS (Railway-Induced Vibration Abatement Solutions), which was conducted over the years 2011–2013, studied ground-borne vibration abatement by addressing vehicle design, track design, soil conditions and maintenance aspects. The work presented in this paper received funding from the European Union Seventh Framework Programme under grant agreement number [265754].