This paper describes work which has greatly improved our understanding
of the processes by which rail corrugation typically develops on Nort
h American Transit systems. Several types of corrugation were identifi
ed from observations and measurements in the field. A new mechanism fo
r corrugation formation is proposed for the most common type of corrug
ation observed and a mathematical model has accordingly been developed
which combines both law frequency and high frequency behaviour of the
vehicle/track system The mathematical model itself plus results from
it and from measurements are discussed here. Novel recommendations far
corrugation mitigation are made.