Rolling Contact Fatigue Cracks on S.N.C.F Conventionnal Tracks

Contact fatigue cracks, often called “SQUATS” or “BLACK SPOTS” appeared in the early eighties. For some years they have been, more or less, associated with wheel burns. Due to the nature of the fatigue cracks, SNCF became very concerned especially as they appear to be more frequent on high speed conventionnal lines (excluding T.G.V)