Condition changes at the rail surface due to the fallen tree leaves and/or other contaminations can cause
the low adhesion levels which present a serious challenge for the traction/braking control systems to
avoid the problem of wheel slip/slide. This paper presents a multiple model based method for the
identification of the adhesion limit to overcome the problem of the wheel slip/slide in poor contact conditions.
The proposed scheme is an indirect method that exploits the dynamic properties of the conventional solid
axle wheelset in response to changes in contact condition at the wheel-rail interface avoiding difficult and
expensive measurement requirements. A nonlinear model of lateral and yaw dynamics of a conventional
solid axle wheelset is used for the study. The non-linearity and changes in the interaction with the rail are
modelled by using a set of non-linear creep/slip curves. The scheme consists of a bank of Kalman filters
based on the linearized wheelset models. Each Kalman filter in the filter bank is optimally tuned to
operate in a specific contact condition. Normalized root mean square values from the residual of each
filter calculated using time moving windows are assessed to identify the operating condition of the
wheelset