Wheel tread roughness on tread-braked wheels (RR-MF-015)

Circumferential profiles have been taken on the treads of tread-braked Class 150 vehicles and Mark II coaches. Corrugations have been identified, with wavelengths in the range 55 - 99 mm, and peak-to-trough heights up to 60 micron. A white layer, of indeterminate origin, has been found at the corrugation peaks.