With support from FRA, Transportation Technology Center Inc. (TTCI) developed a full-scale rolling contact fatigue simulator (RCFS) to research the root causes of wheel and rail surface damage. This damage comprises surface pitting, cracking, wear, and material flow and is a function of both the vertical wheel load (and normal contact stresses) and the steering tractions transmitted across the contact patch. The RCFS can simulate nominal axle loads of up to 49.5 tons. The position and orientation of the wheelset to the track (i.e., angle-of-attack and lateral displacement from the track centerline) can be adjusted to control the steering forces on both high and low rails. High steering tractions on the low rail have been found to develop high-impact wheel and rail damage. TTCI’s task was to determine the limits to these tractions and, in turn, set performance limits for bogies in heavy haul operation in North America. This report describes how the RCFS operates as well as the supporting analysis and initial tests to develop wheel and rail damage on the low rail as part of this effort.