The article is devoted to the problems of analysis and evaluation of the track condition in the plan. The width of the track and, correspondingly, the gauge easement, characterizing the smoothness of the change in track width, are the values determined as the difference in position of the two rail threads in the plan. The shortcomings of gauge easement in the evaluation of the track in curves are considered. The modeling of the empty rolling stock dynamics was performed in the “Universal Mechanism” software package (motion in a shallow curve with speeds from 20 to 90 km/h). The real values of the actual unevenness of the rail threads are taken as a disturbing signal, obtained from the track-meter data with a regular check of the track condition, which are the result of calculating the outlines of the horizontal rail unevenness from the measured rise values. The output of the modeling is the value of the safety factor ( Куст), which should not fall below the value 1.2 in order to comply with the safety conditions for handling the rolling stock along the track. The article provides the Куст dependencies of the empty gondola car on the size of the gauge easement of the natural unevenness of the rail threads in the plan at various speeds of motion in a shallow curve based on the results of the modeling. It is shown that the gauge easement due to the multivariate combination of the position of the inner and outer rail lengths in the curves is not a parameter that uniquely characterizes the geometry of the track gauge in the curves. Authors substantiate the necessity of amending the “gauge easement” parameter with the parameters of the irregularities in the plan of each rail thread.