The article study conditions for the passage of wheelsets along turnouts from the point of view of ensuring traffic safety. The norms and tolerances for geometric dimensions in the “wheelset - rail gauge” system are interrelated. Proceeding from this interrelation, an analysis is performed on the probability of occurrence of adverse events in the passage through the turnouts of wheelsets having flanges with different wear values. The thickness of the flanges of the car wheels has a great influence on the safe passage by the rolling stock on the allocated switch point. When wheels is running on allocated point, disorders occurred in track gauge, tongue gapping to the stock rail, and in the case of frequent repetition of these phenomena - even bends and breaks in connecting rods directly threaten the safety of driving on turnouts. Within one article, it is impossible to consider all the features of the movement of rolling stock in turnouts. As an example, conditions for the passage of a wheelset through a frog unit are considered. It can be seen from the materials presented in the article that the current normative base of the geometric dimensions of the “wheelset - rail gauge” system is justified by the result of extensive and comprehensive scientific research. The experience of several decades of operation is confirmed by the fact that this regulatory framework provides for the transportation process and the safety of the movement of trains in turnouts. Introduction of changes in the “wheelset - rail gauge” measuring system should be based on analysis of the actual state of wheel sets and the parameters of the track gauge in turnouts. In particular, in order to determine the possibility of changing the rejection size of the minimum thickness, it is necessary:• to conduct mass measurements of wheelsets and turnouts in operation; to perform processing of the obtained data with the identification of dependencies between different combinations of sizes, including relations between the thickness of the flange and the slope of its generatrix; to perform dynamic-strength tests to determine the dependence of stresses and deformations of the elements of the switches during the passage of wheelsets with different thicknesses and angles of inclination of the flanges; to reveal the available opportunities for changes in the “wheelset - rail gauge” measuring system, taking into account the durability and reliability of switch points; to develop a new methodology for calculating the adverse events that occur during wheelsets passage along the turnouts.