SHORT-WAVELENGTH RAIL CORRUGATION - FIELD TRIALS AND MEASURING TECHNOLOGY

Two field trials were set up during the period 1974-1984 to help under stand the mechanism of formation of short pitch rail corrugation on Br itish railways. These required the development of novel measuring equi pment: a trolley profilometer and a straight edge device with microcom puter-based recording equipment. Regular monitoring was undertaken of test sections of main-line track. It was found that this type of corru gation arises from a mechanism of differential wear, in which corrugat ion troughs wear barely 10% more than the peaks. Grinding significantl y reduces the roughness on new rail, so that even after 3 months of tr affic the spectrum of roughness on new unground rail is greater than t hat on ground rail by a factor of 10. There is a corresponding delay i n the formation of corrugation. Transverse marks arising from the grin ding operation and with a pitch of 25-30 mm were worn away under traff ic. Wheelslip of up to 15% was measured on a locomotive in service, wh ich is sufficient to give the temperatures required for transformation of a thin layer of the rail surface to martensite. No explanation was found for the corrugation's periodicity.