Statistical description of wheel roughness

Wheel roughness measurements available from several different campaigns are presented in terms of average levels and dispersion. The dependence on factors such as brake type and whether the wheel is powered or trailing is also addressed. A method to decide how many wheels from a train are to be measured is then presented. Finally, the main outcomes are described from a round robin test aimed at assessing the effect on wheel roughness measurements of adopting different equipment, used independently by different teams.