Estimation of wheel/rail adhesion coefficient under wet condition with measured boundary friction coefficient and real contact area

▶ Low adhesion coefficient brings a problem that makes not only a limitation of maximum running speed of vehicles, but also a long distance for stopping vehicles. ▶ Water film between wheel and rail formed in rain or snowfall makes a low adhesion coefficient. ▶ Adhesion coefficient was assessed by elasto-hydrodynamic lubrication (EHL) theory for adopting the boundary friction coefficient and the ratio of real contact area to nominal contact area (RCA/NCA) obtained in experiments.