The influence of precipitation and friction control agents on forces at the wheel/rail interface in heavy haul railways

This paper presents an analysis of the influence of materials that can be present in the so-called “third-body layer” at the wheel/rail interface on curving forces generated in heavy haul operating conditions. The third-body layer is the interfacial layer whose shear properties determine the bulk frictional characteristics that emerge in wheel/rail contact. It is often postulated that precipitation (rain) provides an effective form of lubrication at the wheel tread/rail head interface, reducing curving forces and corresponding wear. The postulate is explored through the analysis of lateral and vertical force data collected under a wide range of environmental conditions in full-scale revenue service. The effects of precipitation are rigorously explored and compared with the effects of top of rail friction modifiers, which are intentionally introduced into the third-body layer.This paper originated from the 2011 IHHA Conference.