Track irregularity is considerably important in track-vehicle studies.
Recorded data of these irregularities form a basis to develop track s
tandards. This also helps specify track inputs to the vehicles. In thi
s paper random field models for vertical irregularity data obtained fr
om Indian railways has been presented. It is shown that irregularity i
n the vertical profile can be modeled as stationary Gaussian random fi
eld, which can be defined in terms of the power spectral density (PSD)
function. Such a model can predict the values of peak amplitudes in a
given track length. Further, the absolute vertical profile of the lef
t and right rails belong to the isotropic random field. The implicatio
n of this in describing the input matrix of multiaxle vehicles is disc
ussed.