The superelevation within a curve of given curvature determines the balance speed of that curve. The vehicle speed in the curve determines whether the vehicle runs over, at, or under the balance speed. The vehicle speed and, consequently, the balance condition in the curve effects the forces at the wheel-rail interface.1,2 Using its Rolling Contact Fatigue Simulator (RCFS), MxV Rail performed tests to study the effects of different balance conditions, under both dry and lubricated contact, on the formation of rolling contact fatigue (RCF). These tests were performed as part of the Association of American Railroads’ (AAR) Strategic Research Initiatives (SRI) program. INTRODUCTION AND BACKGROUND The balance speed within a curve is the speed at which the perceived “centrifugal force” toward the outside of a curve counteracts the gravitational force component directed toward the inside of the curve due to the superelevation of the track. In the following discussion, when…